Co-reporter:Ke Lu;Jintao Zhang;Yueqing Wang;Jizhen Ma;Bin Song
ACS Sustainable Chemistry & Engineering January 3, 2017 Volume 5(Issue 1) pp:821-827
Publication Date(Web):October 24, 2016
DOI:10.1021/acssuschemeng.6b02144
Burgeoning interest in flexible and wearable electronics sparks the rapid development of flexible fiber-shape supercapacitors (SCs). Herein, three-dimensional porous reduced graphene oxide (RGO) aerogel is deposited on flexible Ni wire via a simple aqueous reduction method. RGO aerogel exhibits good capacitive performance, thanks to its unique porous structure and good electrical conductivity. In order to fabricate an asymmetric SC, nickel hydroxide nanosheets are controllably deposited on the RGO sheets as the positive electrode while the RGO aerogel coated Ni wire is used as negative one. The obtained flexible fiber SCs exhibit good performance with high power/energy densities (10.3 kW kg–1/3430 mW cm–3, 24.5 Wh kg–1/0.83 mWh cm–3) and good cycling stability (83% retention, even after 6000 cycles). The solid-state nature combined with good flexibility makes the fiber SCs attractive for energy storage applications in portable and wearable electronics. The interfacial deposition of reduced graphene oxide and nickel hydroxide on Ni wire renders the fabrication of flexible fiber asymmetric supercapacitors for sustainable energy storage.Keywords: Aerogel; Asymmetric supercapacitor; Energy storage; Fiber shape; Reduced graphene oxide;
Co-reporter:Xiuyu Liu;Xingli Feng;Jintao Zhang;Wenjing Li
The Journal of Physical Chemistry C February 5, 2009 Volume 113(Issue 5) pp:1738-1745
Publication Date(Web):Publication Date (Web): January 9, 2009
DOI:10.1021/jp8085123
A simple, one-step wet chemical method was developed for fabrication of closely packed gold nanoprism thin films (Au-PFs for short) on the indium tin oxide (ITO) coated glass substrates. Most Au prisms have micrometer-scale edge length and nanometer-scale thickness (herein defined as nanoprism according to the thickness). They are single crystalline, whose basal surfaces are atomically flat {111} planes and lateral surfaces are {110} planes. The Au-PFs were further used as the substrate electrodes to construct bimetallic and trimetallic Au-based catalysts. A tiny amount of Pt or Pd, the equivalent of a monolayer, was deposited onto the Au nanoprism thin film electrodes (Au-PFEs for short) by the underpotential deposition (UPD) of a Cu atomic layer on the Au surfaces, followed by redox replacement of the UPD Cu with a Pt or Pd monolayer. Interestingly, once after surface modification with a Pt monolayer, Au-PFEs exhibited greatly enhanced catalytic activity toward the electrooxidation of methanol and much better poison resistance than commercial Pt-based catalysts. The as-prepared bimetallic Au−Pt and trimetallic Au−Pd−Pt catalysts are expected to act as the promising electrocatalysts for the methanol oxidation.
Co-reporter:Nan Wang, Hongxiu Dai, Donglei Wang, Houyi Ma, Meng Lin
Materials Science and Engineering: C 2017 Volume 76(Volume 76) pp:
Publication Date(Web):1 July 2017
DOI:10.1016/j.msec.2017.03.077
•An electrochemical sensor was developed for the detection of copper ions.•PPy was functionalized with PA by electrostatic attraction.•The linear range of the copper ions concentration was from 10 to 60 μg·L− 1.This study reports a sensitive electro-analytical method for the determination of trace amounts of Cu2 + using a phytate functionalized polypyrrole nanowires (PPy NWs) modified glass carbon electrode. The phytic acid/polypyrrole (PA/PPy) NWs were prepared by an electrostatic adsorption and ultrasonic mixing. The results showed that both PPy NWs and PA/PPy NWs modified glassy carbon electrodes have electrochemical responses toward Cu2 +. However, owing to the synergistic contribution between the PPy NWs and PA, the PA/PPy NWs modified electrode exhibited higher sensitivity than that of PPy NWs modified electrode. The PA/PPy NWs composites functionalized electrodes showed a good linear relationship with Cu2 + at concentration ranges of 10–60 μg·L− 1, and the limit of detection (S/N = 3) was 3.33 μg·L− 1. In addition, the electrochemical sensor was applied to assay Cu2 + in real water samples.
Co-reporter:Ke Lu;Bin Song;Yuxin Zhang;Jintao Zhang
Journal of Materials Chemistry A 2017 vol. 5(Issue 45) pp:23628-23633
Publication Date(Web):2017/11/21
DOI:10.1039/C7TA07834J
With the rapid development of rechargeable zinc ion (Zn-ion) batteries, it is essential to understand and modulate the energy storage process of the active component to maximize the battery performance. In this research, manganese oxide (MnO2) wrapped zinc hexacyanoferrate (ZnHCF) nanocubes (ZnHCF@MnO2) were prepared using an in situ co-precipitation method. The resulting composite with a unique structure was able to modulate the Zn-ion storage because of the incorporation of capacitive and intercalative properties of both components together with the redox reactions, benefiting from the synergistic effects. Thus, the encapsulation of ZnHCF nanocubes with MnO2 nanosheets gives a high discharge capability for Zn-ion storage with an operation voltage as high as ∼1.7 V. Impressively, the flexible quasi-solid-state Zn-ion battery was assembled using a neutral polymer gel electrolyte, and this resulted in a battery which had potential applications for specific wearable electronics.
Co-reporter:Ke Lu, Bin Song, Kang Li, Jintao Zhang, Houyi Ma
Journal of Power Sources 2017 Volume 370(Volume 370) pp:
Publication Date(Web):1 December 2017
DOI:10.1016/j.jpowsour.2017.10.012
•Advanced hybrid supercapacitor based on CoHCF and MoO3 was fabricated.•The novel flexible supercapacitor showed a large operation potential of 2.0 V.•Simple application of hybrid device was demonstrated by lighting up a LED.•The flexible supercapacitor exhibited high energy density (67.8 Wh kg−1).For the wearable and flexible applications, solid-state supercapacitors have been attracted significant attention owing to their unique features. Herein, we demonstrated the fabrication of a high-energy solid-state hybrid supercapacitor by using cobalt hexacyanoferrate nanoparticles and molybdenum oxide thin films grown on the flexible carbon fiber cloth. The flexible hybrid supercapacitor using a neutral gel electrolyte can be operated in a stable potential window of 2.0 V and delivers a maximal energy density of 67.8 Wh kg−1 at the power density of 1003 W kg−1, outstanding reliability without capacitance degradation under various twisting rates, and remarkable cycling stability retaining 74% of initial capacitance after 10000 cycles.Download high-res image (374KB)Download full-size image
Co-reporter:Ping Zhang;Hui Huang;Nan Wang;Huijuan Li;Dazhong Shen
Microchimica Acta 2017 Volume 184( Issue 10) pp:4037-4045
Publication Date(Web):02 August 2017
DOI:10.1007/s00604-017-2437-3
This paper describes stable and highly dispersed aqueous colloids of polyaniline (PANI) nanofibers that were prepared by a chemical method and used to modify a glassy carbon electrode (GCE). The materials combines the good electrical conductivity and network structure of PANI nanofibers with the complexing capacity of mercaptosuccinic acid. The modified GCEs exhibit high sensitivity to Cd(II) and Pb(II) ions, with detection limits of 50 ng·L−1 and 200 ng·L−1, respectively. The modified GCE was applied to the simultaneous determination of the cancer biomarkers carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP) by using particles of metal-organic frameworks (MOFs) prepared from Pb(II) or Cd(II) and 2-aminoterephthalic acid. The particles are used as electrochemical labels for secondary anti-CEA and secondary anti-AFP antibody in a sandwich assay. The two ions in the MOFs labels on the secondary antibody can be detected best at voltages of −0.63 and −0.88 V (vs Ag/AgCl), respectively. The assay has a linear response in the 0.3 pg·mL−1 to 3 ng·mL−1 concentration range of both CEA and AFP, and the respective detection limits are 0.03 pg·mL−1 and 0.1 pg·mL−1. In our preception, this assay has a wide scope in that it may be applied to a variety of sandwich types of immunoassays.
Co-reporter:Ru Yan;Xiang Gao;Wei He;Rui Guo;Ruonan Wu;Zhuangzhi Zhao
RSC Advances (2011-Present) 2017 vol. 7(Issue 65) pp:41152-41162
Publication Date(Web):2017/08/18
DOI:10.1039/C7RA06186B
A simple and practical method was developed to prepare a series of phytic acid (PA)–metal complex coatings on iron substrate by directly immersing the iron samples in the mixed solutions containing PA and metal ions. The key technologies of fabricating PA–metal complex coatings include: (i) anchoring of PA molecules onto the iron surface via complexation with Fe2+ ions dissolved from the iron substrate, and (ii) layer-by-layer deposition of PA–metal complexes on the PA/Fe2+ bottom layer through the bridging effect of additive metal ions. The present method was applicable to the film-forming process of a variety of metal ions, such as Zn2+, Ca2+, Co2+ and Ni2+, and the as-prepared PA–metal complex coatings were defined as PA–M conversion coatings (M = Zn2+, Ca2+, Co2+ and Ni2+ herein). Due to the strong coordination ability, PA molecules may be self-assembled on the iron surface, forming a layer of organic thin film (here defined as PA film), without the help of additive metal ions. However, the comparison between PA film and PA–M coatings shows that PA–M coatings were much thicker (over 15 μm) and denser and also possessed much stronger anti-corrosion performance compared to the PA film. The present study provides a new path for the fabrication of environmentally-friendly PA-based chemical conversion coatings and further broadens the application range of PA in metal surface pretreatment.
Co-reporter:Xiang Gao, Ke Lu, Lei Xu, Hua Xu, Haifeng Lu, Feng Gao, Shifeng Hou and Houyi Ma
Nanoscale 2016 vol. 8(Issue 3) pp:1555-1564
Publication Date(Web):09 Dec 2015
DOI:10.1039/C5NR07366A
A novel, highly effective and environmentally friendly film-forming material, phytic acid (PA)/silane (denoted as PAS) hybrid with a three-dimensional (3D) network structure, was prepared through a condensation reaction of PA with methyltrihydroxysilane generated from the hydrolysis of methyltriethoxysilane (MTES). Two kinds of PAS-based pretreatment layers, namely NaBrO3-free and NaBrO3-doped PAS layers, were fabricated on iron substrates using the dip-coating method. SEM and AFM observations showed that the as-fabricated PAS-based layers possessed a 3D porous microstructure at the nanoscale and a rough surface morphology. X-ray photoelectron spectroscopic (XPS) and attenuated total reflection infrared (ATR-IR) spectroscopic characterization demonstrated that the above PAS layers bound to the iron surface via the –P–O– bond. Moreover, analyses of steady-state polarization curves and electrochemical impedance spectroscopic (EIS) data indicated that the corrosion rates of the iron substrates decreased considerably in the presence of the two PAS-based pretreatment layers. In particular, the NaBrO3-dosed PAS layer displayed the better corrosion resistance ability as well as maintaining the original microstructure and surface morphology. The PAS-based pretreatment layers are expected to act as substitutes for chromate and phosphate conversion layers and will find widespread application in the surface pretreatment of iron and steel materials due to the advantages of being environmentally friendly, the rapid film-forming process, and, especially, the nanoporous microstructure and rough surface morphology.
Co-reporter:Ke Lu, Jiantie Xu, Jintao Zhang, Bin Song, and Houyi Ma
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 27) pp:17402-17408
Publication Date(Web):June 20, 2016
DOI:10.1021/acsami.6b04587
Porous metal oxide architectures coated with a thin layer of carbon are attractive materials for energy storage applications. Here, a series of porous metal oxide (e.g., vanadium oxides, molybdenum oxides, manganese oxides) foams with/without nitrogen-doped carbon (N–C) coating have been synthesized via a general surfactant-assisted template method, involving the formation of porous metal oxides coated with 1-hexadecylamine (HDA) and a subsequent thermal treatment. The presence of HDA is of importance for the formation of a porous structure, and the successive pyrolysis of such a nitrogen-containing surfactant generates nitrogen-doped carbon (N–C) coated on the surface of metal oxides, which also provides a facile way to adjust the valence states of metal oxides via the carbothermal reduction reaction. When used as electrode materials, the highly porous metal oxides with N–C coating exhibited enhanced performance for lithium ion storage, thanks to the unique 3D structures associated with highly porous structure and thin N–C coating. Typically, the porous metal oxides (V2O5, MoO3, MnO2) exhibited discharge capacities of 286, 303, and 463 mAh g–1 at current densities of 30 and 100 mA g–1, respectively. In contrast, the metal oxides with low valences and carbon coating (VO2@N–C, MoO2@N–C, and MnO@N–C) exhibited improved capacities of 461, 613, and 892 mAh g–1. The capacity retentions of about 87.5, 80.2, and 85.0% for VO2@N–C, MoO2@N–C, and MnO@N–C were achieved after 600 cycles, suggesting the acceptable cycling stability. The present strategy would provide general guidance for preparing porous metal oxide foams with enhanced lithium storage performances.
Co-reporter:Ke Lu, Bin Song, Jintao Zhang, Houyi Ma
Journal of Power Sources 2016 Volume 321() pp:257-263
Publication Date(Web):30 July 2016
DOI:10.1016/j.jpowsour.2016.05.003
•Aqueous Na-Zn hybrid batteries were assembled based on NiHCF and Zn electrodes.•The aqueous battery showed an average operating voltage of 1.5 V.•The aqueous Na-Zn battery exhibited high energy density (62.9 Wh kg−1).Rechargeable aqueous batteries are very attractive as a promising alternative energy storage system, although their reversible capacity is typically limited. A new rechargeable Na-Zn hybrid aqueous battery with nickel hexacyanoferrate (NiHCF) cathode and the nanostructured zinc anode is fabricated. The rational combination of two materials with mild aqueous electrolyte renders the devices with an average operating voltage close to 1.5 V, higher specific capacity of 76.2 mAh g−1, and a good cycling stability with 81% capacity retention for 1000 cycles. These remarkable features can provide guidance for the development of rechargeable batteries from the naturally abundant electrode materials with neutral aqueous electrolytes.
Co-reporter:Ke Lu, Bin Song, Xiang Gao, Hongxiu Dai, Jintao Zhang, Houyi Ma
Journal of Power Sources 2016 Volume 303() pp:347-353
Publication Date(Web):30 January 2016
DOI:10.1016/j.jpowsour.2015.11.031
•Aqueous sodium-ion capacitor was assembled based on CoHCF and CMS electrodes.•The hybrid capacitor cell showed an extended operating cell voltage of 2 V.•The aqueous supercapacitor exhibited high energy density (54.4 Wh kg−1).Sodium-based intercalation aqueous pseudocapacitive energy systems are attractive because of their obvious advantages including improved safety, low cost and environmental friendliness. Herein, an aqueous sodium-ion capacitor with the cobalt hexacyanoferrate (CoHCF) as the cathode electrode and carbon micro-spheres (CMS) as the anode electrode was fabricated, showing an extended operating voltage window (2 V), excellent capacitance behaviour, and high energy density (54.4 Wh kg−1). The present results provide meaningful clues to design new intercalation pseudocapacitor for future practical applications. And these remarkable features may pave the way to next-generation large-scale production of high performance hybrid supercapacitors performed as regulation or complementary devices.Download high-res image (282KB)Download full-size image
Co-reporter:Manman Ren, Mingzhi Yang, Weiliang Liu, Mei Li, Liwei Su, Congde Qiao, Xianbin Wu, Houyi Ma
Electrochimica Acta 2016 Volume 194() pp:219-227
Publication Date(Web):10 March 2016
DOI:10.1016/j.electacta.2016.02.091
Ultra-small Fe3O4 nanocrystals (NCs)/garphene nanosheets (GNSs) composites have been synthesized through a facile gel-like film (GF) assisted method in this work. Fe3O4 NCs with particle size ∼10 nm homogeneously dispersed on 2D GNSs. Profiting from the ultra-small Fe3O4 NCs and GNSs, the composites demonstrate superior long-term and high-rate performance as anode materials for lithium ion batteries. Even at the current density of 5 A g−1, the reversible capacity still maintains 323.4 mAh g−1 after 700 cycles. This work might enlighten us on exploring preferable strategies to develop advanced metal oxides NCs/GNSs composites anode materials for lithium ion batteries or other energy storage devices.Ultra-small Fe3O4 nanocrystals decorated on 2D graphene nanosheets with excellent cycling stability as anode materials for lithium ion batteriesManman Ren, Mingzhi Yang, Weiliang Liu, Mei Li, Liwei Su, Congde Qiao, Xianbin Wu, Houyi MaUltra-small Fe3O4 nanocrystals/graphene nanosheets composites demonstrate excellent long-term cycling stability at high-rate.
Co-reporter:Hui Huang, Wencai Zhu, Xiaochun Gao, Xiuyu Liu, Houyi Ma
Analytica Chimica Acta 2016 Volume 947() pp:32-41
Publication Date(Web):1 December 2016
DOI:10.1016/j.aca.2016.10.012
•One-dimensional phytic acid doped polyaniline nanofibers were prepared.•Phytic acid based nanocomposite was used to detect metal ions for the first time.•Detection limits for Cd and Pb using DPASV were 0.02 and 0.05 μg L−1, respectively.•Cd and Pb in real water samples were measured with satisfactory results.The development of nanostructured conducting polymers based materials for electrochemical applications has attracted intense attention due to their environmental stability, unique reversible redox properties, abundant electron active sites, rapid electron transfer and tunable conductivity. Here, a phytic acid doped polyaniline nanofibers based nanocomposite was synthesized using a simple and green method, the properties of the resulting nanomaterial was characterized by electrochemical impedance spectroscopy (EIS), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). A glassy carbon electrode modified by the nanocomposite was evaluated as a new platform for the simultaneous detection of trace amounts of Cd2+ and Pb2+ using differential pulse anodic stripping voltammetry (DPASV). The synergistic contribution from PANI nanofibers and phytic acid enhances the accumulation efficiency and the charge transfer rate of metal ions during the DPASV analysis. Under the optimal conditions, good linear relationships were obtained for Cd2+ in a range of 0.05–60 μg L−1, with the detection limit (S/N = 3) of 0.02 μg L−1, and for Pb2+ in a range of 0.1–60 μg L−1, with the detection limit (S/N = 3) of 0.05 μg L−1. The new electrode was successfully applied to real water samples for simultaneous detection of Cd2+ and Pb2+ with good recovery rates. Therefore, the new electrode material may be a capable candidate for the detection of trace levels of heavy metal ions.
Co-reporter:Nan Wang, Meng Lin, Hongxiu Dai, Houyi Ma
Biosensors and Bioelectronics 2016 Volume 79() pp:320-326
Publication Date(Web):15 May 2016
DOI:10.1016/j.bios.2015.12.056
•Thymine bases modified an electrode for Hg2+ sensor was prepared.•The biosensor was found to be highly sensitive and selective to mercury ions.•The specific affinity to mercury ions based on T–Hg2+–T coordination chemistry.•The electrochemical sensor was stable and reusable with regeneration.A sensitive, selective and reusable electrochemical biosensor for the determination of mercury ions (Hg2+) has been developed based on thymine (T) modified gold nanoparticles/reduced graphene oxide (AuNPs/rGO) nanocomposites. Graphene oxide (GO) was electrochemically reduced on a glassy carbon substrate. Subsequently, AuNPs were deposited onto the surface of rGO by cyclic voltammetry. For functionalization of the electrode, the carboxylic group of the thymine-1-acetic acid was covalently coupled with the amine group of the cysteamine which self-assembled onto AuNPs. The structural features of the T bases functionalized AuNPs/rGO electrode were confirmed by attenuated total reflection infrared (ATR-IR) spectroscopy and scanning electron microscopy (SEM) spectroscopy. Each step of the modification process was characterized by cyclic voltammetry (CV) and electrochemical impedence spectroscopy (EIS). The T bases modified AuNPs/rGO electrode was applied to detect various trace metal ions by differential pulse voltammetry (DPV). The proposed biosensor was found to be highly sensitive to Hg2+ in the range of 10 ng/L–1.0 µg/L. The biosensor afforded excellent selectivity for Hg2+ against other heavy metal ions such as Zn2+, Cd2+, Pb2+, Cu2+, Ni2+, and Co2+. Furthermore, the developed sensor exhibited a high reusability through a simple washing. In addition, the prepared biosensor was successfully applied to assay Hg2+ in real environmental samples.
Co-reporter:Ke Lu, Dan Li, Xiang Gao, Hongxiu Dai, Nan Wang and Houyi Ma
Journal of Materials Chemistry A 2015 vol. 3(Issue 31) pp:16013-16019
Publication Date(Web):30 Jun 2015
DOI:10.1039/C5TA04244E
This paper demonstrates how to design and construct an advanced aqueous sodium-ion supercapacitor by using manganous hexacyanoferrate (MnHCF) as the cathode material and Fe3O4/rGO nanocomposites as the anode material. The rational combination of these two materials with neutral aqueous electrolytes provides the devices with an extended voltage of 1.8 V, much higher power density (2183.5 W kg−1) and energy density (27.9 W h kg−1) compared with similar devices reported in the literature. The devices also have good cycling stability with 82.2% capacity retention even after 1000 cycles. More significantly, the supercapacitors are designed with low cost and environmentally benign materials and are more suitable for future large-scale practical applications.
Co-reporter:Caicai Zhao, Xiang Gao, Haifeng Lu, Ru Yan, Chuntao Wang and Houyi Ma
RSC Advances 2015 vol. 5(Issue 67) pp:54420-54432
Publication Date(Web):15 Jun 2015
DOI:10.1039/C5RA03899E
Mono-n-butyl phosphate (BP) and mono-n-hexyl phosphate (HP) thin films were directly formed on an iron surface by immersing pure iron samples in aqueous solutions containing BP or HP. FTIR analyses, XPS characterizations and water contact angle data show that the iron surfaces were covered with the BP or HP thin films. The spontaneous formation of alkyl phosphate thin films on the iron surface is largely attributed to the electrostatic interaction between Fe2+ ions on the surface of iron and RO–PO3H− (R represents n-butyl or n-hexyl) ions and the specific adsorption of phosphate groups on the iron substrate. Moreover, electrochemical results clearly demonstrate that the as-formed thin films can effectively protect the iron substrate from corrosion in NaCl corrosive solutions.
Co-reporter:Xiang Gao, Shaotong Liu, Haifeng Lu, Feng Gao, and Houyi Ma
Industrial & Engineering Chemistry Research 2015 Volume 54(Issue 7) pp:1941
Publication Date(Web):January 30, 2015
DOI:10.1021/ie503508h
The inhibition effect of three amphiphilic monoalkyl phosphate esters with different chain lengths—mono-n-butyl phosphate ester (BP), mono-n-hexyl phosphate ester (HP), and mono-n-octyl phosphate ester (OP)—on the corrosion of iron in 0.5 M H2SO4 solutions was investigated by using electrochemical impedance spectroscopy (EIS) and polarization curve methods. The electrochemical results indicate that BP, HP, and OP all acted as mixed-type corrosion inhibitors with a dominant cathodic effect. BP shows the lowest inhibition efficiency as compared to HP or OP. However, the inhibition efficiency of HP is almost the same with that of OP under similar conditions because the molecular aggregation state at the iron/solution interface plays a more important role. X-ray photoelectron spectroscopic (XPS) characterization demonstrates that three alkyl phosphate esters adsorbed on the iron surface through the un-ionized P–OH groups. The adsorption of BP, HP, and OP fitted well with the Langmuir model.
Co-reporter:Hui Huang, Ting Chen, Xiuyu Liu, Houyi Ma
Analytica Chimica Acta 2014 Volume 852() pp:45-54
Publication Date(Web):10 December 2014
DOI:10.1016/j.aca.2014.09.010
•Three-dimensional graphene-MWCNTs nanocomposites were prepared.•Graphene-MWCNTs based electrochemical sensor was used to detect heavy metal ions for the first time.•The proposed sensor was certified capable for real sample with satisfactory results.A green and facile method was developed to prepare a novel hybrid nanocomposite that consisted of one-dimensional multi-walled carbon nanotubes (MWCNTs) and two-dimensional graphene oxide (GO) sheets. The as-prepared three-dimensional GO–MWCNTs hybrid nanocomposites exhibit excellent water-solubility owing to the high hydrophilicity of GO components; meanwhile, a certain amount of MWCNTs loaded on the surface of GO sheets through π–π interaction seem to be “dissolved” in water. Moreover, the graphene(G)-MWCNTs nanocomposites with excellent conductivity were obtained conveniently by the direct electrochemical reduction of GO–MWCNTs nanocomposites. Seeing that there is a good synergistic effect between MWCNTs and graphene components in enhancing preconcentration efficiency of metal ions and accelerating electron transfer rate at G-MWCNTs/electrolyte interface, the G-MWCNTs nanocomposites possess fast, simultaneous and sensitive detection performance for trace amounts of heavy metal ions. The electrochemical results demonstrate that the G-MWCNTs nanocomposites can act as a kind of practical sensing material to simultaneously determine Pb2+ and Cd2+ ions in terms of anodic stripping voltammetry (ASV). The linear calibration plots for Pb2+ and Cd2+ ranged from 0.5 μg L−1 to 30 μg L−1. The detection limits were determined to be 0.2 μg L−1 (S/N = 3) for Pb2+ and 0.1 μg L−1 (S/N = 3) for Cd2+ in the case of a deposition time of 180 s. It is worth mentioning that the G-MWCNTs modified electrodes were successfully applied to the simultaneous detection of Cd2+ and Pb2+ ions in real electroplating effluent samples containing lots of surface active impurities, showing a good application prospect in the determination of trace amounts of heavy metals.
Co-reporter:Xuemei Ma, Tingting Miao, Wencai Zhu, Xiaochun Gao, Chuntao Wang, Caicai Zhao and Houyi Ma
RSC Advances 2014 vol. 4(Issue 101) pp:57842-57849
Publication Date(Web):21 Oct 2014
DOI:10.1039/C4RA08543D
First, polyaniline–graphene oxide (GO–PANI) nanocomposites were prepared by the in situ polymerization of aniline in the presence of graphene oxide (GO). Next, the GO–PANI nanocomposites were reduced to polyaniline–graphene (G–PANI) nanocomposites by a green electrochemical reduction method. Finally, a thin layer of nearly monodispersed Au nanoparticles with a uniform size (∼12 nm) was coated on the surface of the G–PANI nanocomposites. Moreover, the as-prepared Au–polyaniline–graphene (Au–G–PANI) nanocomposites can be used as a sensing electrode material for the electrochemical detection of nitrite (NO2−). Compared with other common modified electrodes, the Au–G–PANI/GCE shows an obvious oxidation peak of NO2− with a larger peak current, and gives a wider linear range from 0.1 to 200 μmol L−1, with a detection limit of 0.01 μmol L−1 (S/N = 3). Besides, the oxidation process of NO2− on the Au–G–PANI/GCE is proven to be a surface-controlled process involving the transfer of two electrons. The present study widens the applications of graphene-based nanocomposite materials in the electrochemical detection of environmental pollutants.
Co-reporter:Ke Lu, Rongyan Jiang, Xiang Gao and Houyi Ma
RSC Advances 2014 vol. 4(Issue 94) pp:52393-52401
Publication Date(Web):01 Oct 2014
DOI:10.1039/C4RA11088A
This work studied the pseudocapacitive behavior of Fe3O4 and examined approaches to improve its electrochemical activity. Our results show that by optimizing the electrode architectures, we were able to construct ternary Fe3O4/CNTs/PANI composites that delivered excellent electroactivity and cyclic stability because of synergistic effects from each component. In this composite, CNTs were uniformly coated on the surface of Fe3O4 particles and were able to form conductive networks that electrically wired each particle, whereas PANI particles were able to bridge Fe3O4/CNTs composites and further ensure the overall mechanical integrity. Overall, with 8 wt% of PANI the electrodes were able to deliver a high specific capacitance of 260 F g−1 at 0.5 A g−1. The electrodes also had excellent cyclic stability and showed only 6% decay capacity after 1000 cycles.
Co-reporter:Xiang Gao, Caicai Zhao, Haifeng Lu, Feng Gao, Houyi Ma
Electrochimica Acta 2014 150() pp: 188-196
Publication Date(Web):
DOI:10.1016/j.electacta.2014.09.160
Co-reporter:Ting Chen, Xiaowei Li, Cuicui Qiu, Wencai Zhu, Houyi Ma, Shenhao Chen, Oliver Meng
Biosensors and Bioelectronics 2014 Volume 53() pp:200-206
Publication Date(Web):15 March 2014
DOI:10.1016/j.bios.2013.09.059
•The carbon cloth-supported Co3O4/PbO2 core-shell nanorod arrays were firstly fabricated.•The carbon cloth-supported Co3O4/PbO2 nanorod array electrode was directly used as the flexible glucose sensor.•The flexible glucose sensor displayed low detection limit and high sensitivity for the detection of glucose.•The sensing performance of this type of flexible glucose sensors were evaluated by measuring human serum samples.A novel electrochemical sensor for the detection of glucose was constructed based on the use of Co3O4/PbO2 core-shell nanorod arrays as electrocatalysts. In this paper the Co3O4/PbO2 core-shell nanorod arrays grow directly on a flexible carbon cloth substrate by the combination of hydrothermal synthesis and electrochemical deposition methods. The as-prepared hierarchical nanocomposites show the structural characteristics of nanowire core and nanoparticle shell. The carbon cloth-supported Co3O4/PbO2 nanorod array electrode exhibits higher sensitivity (460.3 μA mM−1 cm−2 in the range from 5 μM to 1.2 mM) and lower detection limit (0.31 μM (S/N=3)) than the carbon cloth-supported Co3O4 nanowire array electrode. Both the three-dimensional network of carbon cloth substrate and the hierarchical nanostructure of binary Co3O4/PbO2 composites make such an electrode have high electrocatalytic activity towards the glucose oxidation. Due to the excellent sensitivity, repeatability and anti-interference ability, the carbon cloth-supported Co3O4/PbO2 nanorod arrays will be the promising materials for fabricating practical non-enzymatic glucose sensors.
Co-reporter:Wencai Zhu, Hui Huang, Xiaochun Gao, Houyi Ma
Materials Science and Engineering: C 2014 Volume 45() pp:21-28
Publication Date(Web):1 December 2014
DOI:10.1016/j.msec.2014.08.067
•The 4-ABA/ERGO/GCE was fabricated by a two-step electrochemical method.•Electrochemical behavior of acetaminophen at the 4-ABA/ERGO/GCE was investigated.•The electrochemical sensor exhibited a low detection limit and good selectivity.•This sensor was applied to the detection of acetaminophen in commercial tablets.Poly(4-aminobenzoic acid)/electrochemically reduced graphene oxide composite film modified glassy carbon electrodes (4-ABA/ERGO/GCEs) were fabricated by a two-step electrochemical method. The electrochemical behavior of acetaminophen at the modified electrode was investigated by means of cyclic voltammetry. The results indicated that 4-ABA/ERGO composite films possessed excellent electrocatalytic activity towards the oxidation of acetaminophen. The electrochemical reaction of acetaminophen at 4-ABA/ERGO/GCE is proved to be a surface-controlled process involving the same number of protons and electrons. The voltammetric determination of acetaminophen performed with the 4-ABA/ERGO modified electrode presents a good linearity in the range of 0.1–65 μM with a low detection limit of 0.01 μM (S/N = 3). In the case of using the 4-ABA/ERGO/GCE, acetaminophen and dopamine can be simultaneously determined without mutual interference. Furthermore, the 4-ABA/ERGO/GCE has good reproducibility and stability, and can be used to determine acetaminophen in tablets.
Co-reporter:Rongyan Jiang, Congying Cui, Houyi Ma
Electrochimica Acta 2013 Volume 104() pp:198-207
Publication Date(Web):1 August 2013
DOI:10.1016/j.electacta.2013.04.125
Graphene nanosheets (GNs) were directly used as a type of novel but powerful planar conductive additive in the α-MnO2-based electrode material for electrochemical capacitors (ECs), to improve the low electronic conductivity of α-MnO2. It was found that the specific capacitance (SC) and cycling performance of α-MnO2 were obviously enhanced when GNs co-existed with acetylene black (AB), a conventional carbon-based conductive agent, at an appropriate weight ratio in the electrode material (GNs and AB were 10 wt% and 5 wt% of total weight, respectively). The unusual phenomenon was attributed to the following two reasons: (i) the planar graphene conductive additive could bridge active α-MnO2 particles more effectively via a “plane-to-point” conducting mode and (ii) AB particles might serve as the fillings in the electrode material and connect the isolated α-MnO2 particles to GNs through a “filling effect”, thereby constructing a novel and more effective conducting network. In this way, the synergy effect between the “plane-to-point” mode (due to GNs) and the “filling” mode (due to AB) significantly decreased the charge-transfer resistance of the α-MnO2-based electrode. With much faster charge-transfer process, the capacitive performance of α-MnO2 was greatly enhanced. On the contrary, when GNs were excess, the effective conducting network was weakened by the agglomeration of GNs and the absence of AB, leading to a lower conductivity and non-enhanced capacitive performance of α-MnO2.
Co-reporter:Ting Chen, Hui Huang, Houyi Ma, Delong Kong
Electrochimica Acta 2013 Volume 88() pp:79-85
Publication Date(Web):15 January 2013
DOI:10.1016/j.electacta.2012.10.009
As the positive active material of lead-acid battery, microstructure and surface morphology of lead dioxide (PbO2) have a strong influence on the overall performance of lead-acid battery. In this paper, we fabricated a series of PbO2 thin films on the pure Pb surface by means of the electrochemical oxidation of Pb substrate and used the as-fabricated Pb electrodes coated with PbO2 thin films as the model electrodes to study the dependence of electrochemical properties of PbO2 materials on their microstructure and morphology, thereby providing necessary technical basis for the improvement of electrochemical performance of PbO2 active materials. Herein nanostructured PbO2 thin films were electrochemically prepared using a galvanostatic oxidation method in dilute H2SO4 solution. The electrochemical properties of the PbO2 films with different structure and morphology were investigated by using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and constant current charge/discharge methods. The results demonstrated that the PbO2 layer formed at a current density of 10 mA cm−2 possessed the higher discharge capacity and the better cycle performance than the other PbO2 layers, due to high surface area, relatively small and uniform size, and especially good connectivity between PbO2 nanoparticles. The possible factors that affect electrochemical properties of different PbO2 thin films were interpreted in detail.Highlights► Nanostructured PbO2 thin films were fabricated on the Pb substrate by a direct galvanostatic oxidation method. ► Effects of the microstructure of PbO2 thin films on their electrochemical properties were investigated. ► The micro/nanostructured PbO2 materials can improve their electrochemical performance.
Co-reporter:Rongyan Jiang, Congying Cui and Houyi Ma
Physical Chemistry Chemical Physics 2013 vol. 15(Issue 17) pp:6406-6415
Publication Date(Web):04 Mar 2013
DOI:10.1039/C3CP44516J
Graphene nanosheets (GNs) were directly used as a type of novel but powerful planar conductive additive in spinel LiMn2O4 (LMO)-based electrodes, to improve the low electronic conductivity of LMO. It was found that the specific capacity and cycling performance of LMO were obviously enhanced when GNs co-existed with acetylene black (AB), a conventional carbon-based conductive agent, at an appropriate weight ratio in the LMO-based electrode (GNs and AB were 5 wt% and 10 wt% of the total weight, respectively). The unusual phenomenon was attributed to the following two reasons: (i) the planar GNs could bridge LMO particles more effectively via a “plane-to-point” conducting mode; (ii) AB particles might serve as the fillings in the electrode and connect the isolated LMO particles to GNs through a “filling effect”, thereby constructing a novel and more effective conducting network. In this way, the synergy effect between the “plane-to-point” conducting mode (due to GNs) and the “filling” mode (due to AB) significantly decreased the charge-transfer resistance of the LMO-based electrode. With the much faster charge-transfer process, the rate performance of LMO was greatly enhanced. In contrast, when GNs were in excess, the effective conducting network was weakened by the agglomeration of GNs and the absence of AB, so the conductivity and the rate performance of LMO were not improved and even decreased.
Co-reporter:Rongyan Jiang, Congying Cui, Houyi Ma
Materials Letters 2013 Volume 91() pp:12-15
Publication Date(Web):15 January 2013
DOI:10.1016/j.matlet.2012.09.056
LiMn2O4 nanoparticles have been prepared by adding poly(vinyl pyrrolidone) (PVP) through a one-step hydrothermal method while PVP acts as reducing reagent. The dosage of PVP is studied and LiMn2O4 prepared with 10 mL PVP solution (10-LMO) shows high capacity and excellent cycling property during galvanostatic charge/discharge test. Initial discharge capacity of 112 mAh g−1 can be delivered at 5 C while the capacity retention is 93% after 100 cycles. Electrochemical impedance spectroscopy (EIS) results demonstrate that the 10-LMO electrode has the lowest resistance. So the migration and diffusion of Li+ at the electrode surface of 10-LMO electrode is fast, resulting excellent rate performance.Highlights► LiMn2O4 nanoparticles were prepared by adding PVP. ► PVP acted as reducing agent in the hydrothermal reaction. ► LiMn2O4 prepared with 10 mL PVP (10-LMO) showed excellent rate performance. ► The resistance of 10-LMO electrode was lower than others. ► The migration and diffusion of Li+ of 10-LMO electrode was faster.
Co-reporter:Wencai Zhu, Ting Chen, Xuemei Ma, Houyi Ma, Shenhao Chen
Colloids and Surfaces B: Biointerfaces 2013 Volume 111() pp:321-326
Publication Date(Web):1 November 2013
DOI:10.1016/j.colsurfb.2013.06.026
•A facile method for the synthesis of hollow Au nanoparticles uniformly attached on the graphene was developed.•The as-prepared hollow Au nanoparticles-graphene nanocomposites possess high surface area, good conductivity, prominent electronic transport property and excellent catalytic activity.•The as-prepared nanocomposites exhibit enhanced electrocatalytic performance toward dopamine.•Highly sensitive and selective detection of dopamine at the hollow Au nanoparticles-graphene nanocomposite modified electrode was achieved.Highly dispersed hollow gold-graphene (HAu-G) nanocomposites were synthesized by a two-step method. The immobilization of hollow gold nanoparticles (HAu NPs) onto the surface of graphene sheets was achieved by mixing an aqueous solution of HAu NPs with a poly(N-vinylpyrrolidone)-functionalized graphene dispersion at room temperature. A glassy carbon electrode (GCE) was modified with the nanocomposites, and the as-prepared modified electrode displayed high electrocatalytic activity and extraordinary electronic transport properties. Amperometric detection of dopamine (DA) performed with the HAu-G modified electrode exhibits a good linearity between 0.08 and 600 μM with a low detection limit of 0.05 μM (S/N = 3) and also possesses good reproducibility and operational stability. The interference of ascorbic acid (AA) and uric acid (UA) can be excluded when using differential pulse voltammetric technique. In addition, this type of modified electrode can also be applied to the determination of DA content in dopamine hydrochloride injection. It is obvious that the HAu-G modified electrode provides a new way to detect dopamine sensitively and selectively.
Co-reporter:Cuicui Qiu, Ting Chen, Xia Wang, Ying Li, Houyi Ma
Colloids and Surfaces B: Biointerfaces 2013 Volume 103() pp:129-135
Publication Date(Web):1 March 2013
DOI:10.1016/j.colsurfb.2012.10.017
A facile electrodeposition method was used to fabricate nanostructured Au thin films. Construction of the amperometric biosensors for 4-chlorophenol (4-CP) is based on the immobilization of horseradish peroxidase (HRP) on the Au thin films via a simple method. The as-prepared nano-Au films provide a favorable microenvironment for the immobilization of HRP and the retention of its activity. With H2O2 as oxidizing co-substrate, the HRP modified electrode displays high catalytic activity toward 4-CP. Besides, it has been demonstrated that the immobilization of HRP has a significant positive effect on the anti-fouling performance of the electrode material. Furthermore, the enzyme modified electrode was used as a bioelectrochemical sensor of 4-CP, exhibiting linear relationship in two different concentration ranges: from 2.5 to 40 μM and from 62.5 to 117.5 μM, with a detection limit of 0.39 μM (S/N = 3) at an applied potential of −0.55 V. The fast current response and good stability were obtained on the HRP modified electrode.Graphical abstractHighlights► A facile electrodeposition technique was used to fabricate nano-Au thin films. ► The direct electrochemical behavior is obtained on the immobilized HRP. ► The anti-fouling performance was improved to a great extent by the immobilized HRP. ► An amperometric sensor of 4-CP with an excellent sensing capability was achieved.
Co-reporter:Xiu-yu Liu;Cong-ying Cui;Ying-wen Cheng
International Journal of Minerals, Metallurgy, and Materials 2013 Volume 20( Issue 5) pp:486-492
Publication Date(Web):2013 May
DOI:10.1007/s12613-013-0755-y
Gold nanoparticles with different shapes and sizes were prepared by adding gold precursor (HAuCl4) to an electrolyzed aqueous solution of poly(N-vinylpyrrolidone) (PVP) and KNO3, which indicates the good reducing capacity of the PVP-containing solution after being treated by electrolysis. Using a catholyte and an anolyte as the reducing agents for HAuCl4, respectively, most gold nanoparticles were spherical particles in the former case but plate-like particles in the latter case. The change in the pH value of electrolytes caused by the electrolysis of water would be the origin of the differences in shape and morphology of gold nanoparticles. A hypothesis of the H+ or OH− catalyzed PVP degradation mechanism was proposed to interpret why the pH value played a key role in determining the shape or morphology of gold nanoparticles. These experiments open up a new method for effectively controlling the shape and morphology of metal nanoparticles by using electrochemical methods.
Co-reporter:Ting Chen, Houyi Ma, Delong Kong
Materials Letters 2013 90() pp: 103-106
Publication Date(Web):
DOI:10.1016/j.matlet.2012.09.058
Co-reporter:Xuemei Ma;Zhaona Liu;Cuicui Qiu;Ting Chen
Microchimica Acta 2013 Volume 180( Issue 5-6) pp:461-468
Publication Date(Web):2013 April
DOI:10.1007/s00604-013-0949-z
We have synthesized a virtually monodisperse gold-graphene (Au-G) nanocomposite by a single-step chemical reduction method in aqueous dimethylformamide solution. The nanoparticles are homogenously distributed over graphene nanosheets. A glassy carbon electrode was modified with this nanocomposite and displayed high electrocatalytic activity and extraordinary electronic transport properties due to its large surface area. It enabled the simultaneous determination of hydroquinone (HQ) and catechol (CC) in acetate buffer solution of pH 4.5. Two pairs of well-defined, quasi-reversible redox peaks are obtained, one for HQ and its oxidized form, with a 43 mV separation of peak potentials (ΔEp), the other for CC and its oxidized form, with a ΔEp of 39 mV. Due to the large separation of oxidation peak potentials (102 mV), the concentrations of HQ and CC can be easily determined simultaneously. The oxidation peak currents for both HQ and CC increase linearly with the respective concentrations in the 1.0 μM to 0.1 mM concentration range, with the detection limits of 0.2 and 0.15 μM (S/N = 3), respectively. The modified electrode was successfully applied to the simultaneous determination of HQ and CC in spiked tap water, demonstrating that the Au-G nanocomposite may act as a high-performance sensing material in the selective detection of some environmental pollutants.
Co-reporter:Cuicui Qiu, Xia Wang, Xueying Liu, Shifeng Hou, Houyi Ma
Electrochimica Acta 2012 Volume 67() pp:140-146
Publication Date(Web):15 April 2012
DOI:10.1016/j.electacta.2012.02.011
Glucose oxidase (GOx) was stably immobilized via a simple physical adsorption method onto the nanostructured Au thin films fabricated by using electrodeposition and galvanic replacement technology, which provides a facile method to prepare morphology-controllable Au films and also facilitates the preparation and application of enzyme modified electrodes. An obvious advantage of the as-prepared enzyme electrode (denoted as GOx/Au/GCE) is that the nano-Au films provide a favorable microenvironment for GOx and facilitate the electron transfer between the active center of GOx and electrodes. Cyclic voltammetry (CV) results indicate that the immobilized GOx displayed a direct, reversible and surface-confined redox reaction in the phosphate buffer solution. Furthermore, the enzyme modified electrode was used as a glucose bioelectrochemical sensor, exhibiting a linear relationship in the concentration ranges of 2.5–32.5 μmol L−1 and 60–130 μmol L−1 with a detection limit of 0.32 μmol L−1 (S/N = 3) at an applied potential of −0.55 V. Due to the excellent stability, sensitivity and anti-interference ability, the Au thin films are hopeful in the construction of glucose biosensors.Graphical abstractHighlights► Au thin films are formed by electrodeposition and galvanic replacement technology. ► Glucose oxidase is stably immobilized via a simple physical adsorption method. ► The direct electrochemical behavior is obtained on the immobilized glucose oxidase. ► An amperometric sensor of glucose with an excellent sensing capability is achieved.
Co-reporter:Zhaona Liu;Huacheng Zhang;Shifeng Hou
Microchimica Acta 2012 Volume 177( Issue 3-4) pp:427-433
Publication Date(Web):2012 June
DOI:10.1007/s00604-012-0801-x
Nanoporous gold (NPG) with uniform pore sizes and ligaments was prepared by using a simple dealloying method. NPG electrodes exhibit excellent electrocatalytic activity towards the oxidation of CySH and the mechanism for the electrochemical reaction of CySH on NPG has been discussed. Interestingly, if the operating potential is fixed at 0.65 V, a strong current is observed and interferences by tryptophan and tyrosine are avoided. The calibration plot is linear in the concentration range from 1 μM to 400 μM (R2 = 0.994), and the quantification limit is as low as 50 nM. The NPG-modified electrode has good reproducibility, high sensitivity and selectivity, can be used to sense CySH in aqueous solution.
Co-reporter:Ting Chen, Zhaona Liu, Weijie Lu, Xingfeng Zhou, Houyi Ma
Electrochemistry Communications 2011 Volume 13(Issue 10) pp:1086-1089
Publication Date(Web):October 2011
DOI:10.1016/j.elecom.2011.07.001
A novel converse dealloying method was developed to fabricate free-standing nanoporous silver (np-Ag). One remarkable characteristic of the new dealloying method is that inert component (Au) is selectively removed from Au–Ag alloys while active component (Ag) is left undissolved. Thiourea plays a key role in the formation of a free-standing porous Ag framework since it not only leads to anodic dissolution of Au component but also causes the surface passivation of Ag component. Because of the excellent electrocatalytic activity toward the reduction of trichloroacetic acid (TCA), the as-prepared np-Ag materials can be directly used as working electrodes to detect TCA in the concentration range from 2.50 to 25.0 mM.Highlights► A converse dealloying method was developed to prepare free-standing nanoporous silver (np-Ag). ► The free-standing nanoporous silver (np-Ag) can be used directly as the working electrode. ► The np-Ag displayed high sensitivity and fast response for the detection of trichloroacetic acid (TCA).
Co-reporter:Wenjing Li, Houyi Ma, Lihui Huang and Yi Ding
Physical Chemistry Chemical Physics 2011 vol. 13(Issue 13) pp:5565-5568
Publication Date(Web):21 Feb 2011
DOI:10.1039/C0CP02178D
Well-defined nanoporous palladium (np-Pd) fabricated by a modified electrochemical dealloying procedure is demonstrated to be an excellent electrocatalyst material for reductive degradation of both carbon tetrachloride and chlorobenzene.
Co-reporter:Cuicui Qiu, Yongen Guo, Jintao Zhang, Houyi Ma, Yaqi Cai
Materials Chemistry and Physics 2011 Volume 127(Issue 3) pp:484-488
Publication Date(Web):15 June 2011
DOI:10.1016/j.matchemphys.2011.02.041
A series of bimetallic Pt–Au thin films with different Pt/Au ratios were fabricated on glassy carbon (GC) substrates through galvanic replacement reactions between hierarchical Co thin films prepared by cyclic voltammetric deposition and mixed solutions of HAuCl4 and H2PtCl6. The morphologies of the as-prepared Pt–Au thin films resemble those of the sacrificial Co templates, and the Pt/Au ratios in the films are dependent on the HAuCl4/H2PtCl6 molar ratios in the mixed solutions. Because of good stability and excellent synergistic effect of Au and Pt, the bimetallic films with novel structures display unexpected high catalytic activity for the oxidation of formic acid. The as-prepared hierarchical Pt–Au micro/nanostructures are expected to find applications as catalysts in direct formic acid fuel cells (DFAFCs).Highlights► Pt–Au thin films with different Pt/Au ratios were prepared by galvanic replacement. ► Pt/Au ratios are dependent on the HAuCl4/H2PtCl6 molar ratios in the electrolyte. ► The bimetallic films display high catalytic activity for the oxidation of HCOOH.
Co-reporter:Cuicui Qiu, Xiaoqiang Dong, Minghu Huang, Sihui Wang, Houyi Ma
Journal of Molecular Catalysis A: Chemical 2011 350(1–2) pp: 56-63
Publication Date(Web):1 November 2011
DOI:10.1016/j.molcata.2011.09.004
A series of nanostructured Pd–Fe bimetallic thin films with the performance of fast and high-efficiency electrochemical reductive dechlorination were directly formed on glassy carbon electrodes (GCEs) through galvanic replacement of partial Fe0 nanoparticles by Pd(II) ions. The composition and morphology of such Pd–Fe thin films are strongly dependent on the sacrificial Fe film templates fabricated by a template-free, double-potential step electrodeposition technique. The size, shape and morphology of the Fe nanoparticles that constitute the Fe thin films can be controlled well by adjusting the concentration of Fe2+ ions in electrolyte solutions. Due to the good synergistic effect between Pd and Fe, the as-prepared Pd–Fe thin films with the novel microstructure display a high reactivity towards the electrochemical reductive dechlorination of carbon tetrachloride (CT), which closely related to the composition of Pd–Fe thin films, applied potential and temperature. The dechlorination reaction of CT complied with pseudo-first-order kinetics.Graphical abstractDownload high-res image (166KB)Download full-size imageHighlights► Developing a facile electrodeposition technique for fabricating Fe nano-films. ► Fabrication of nanostructured Pd–Fe thin films via a galvanic replacement reaction. ► Composition, morphology and microstructure of the Pd–Fe films can be controlled. ► Pd–Fe nano-catalysts exhibit very high activity for the CT dechlorination. ► Distinguishing the dechlorination activity of different types of hydrogen.
Co-reporter:Cuicui Qiu, Jintao Zhang, Houyi Ma
Solid State Sciences 2010 Volume 12(Issue 5) pp:822-828
Publication Date(Web):May 2010
DOI:10.1016/j.solidstatesciences.2010.02.011
Co thin films with novel hierarchical structures were controllably fabricated by simple electrochemical deposition in the absence of hard and soft templates, which were used as sacrificial templates to further prepare noble metal (Pd, Pt, Au) hierarchical micro/nanostructures via metal exchange reactions. SEM characterization demonstrated that the resulting noble metal thin films displayed hierarchical architectures. The as-prepared noble metal thin films could be directly used as the anode catalysts for the electro-oxidation of formic acid. Moreover, bimetallic catalysts (Pt/Au, Au/Pt) fabricated based on the monometallic Au, Pt micro/nanostructures exhibited the higher catalytic activity compared to the previous monometallic catalysts.
Co-reporter:Jiaqi Zhang, Wenjing Li, Yingwen Cheng, Xiaokao Zhang, Shaoxin Huang, Houyi Ma
Materials Chemistry and Physics 2010 Volume 119(1–2) pp:188-194
Publication Date(Web):15 January 2010
DOI:10.1016/j.matchemphys.2009.08.038
Flat gold prisms that have micrometer-scale edge length and nanometer-scale thickness (micro-prisms, as defined by edge length of prisms) were synthesized through a facile solution-phase synthetic method. Two effective measures were adopted in order to prepare the well-defined micro-prisms: (i) selecting poly(N-vinylpyrrolidone)(PVP) as the shape-directing agent to induce the preferential growth of small gold nanocrystals and (ii) using a weak reducing agent, ethylene glycol (EG), to slow down the reduction rate of AuCl4− ions. Besides, the light played an important role in inducing the formation of tiny nanoprisms in the early stages of Au(III) ion reduction. Considering that gold nanoclusters have a strong tendency to heterogeneous nucleation at solid/liquid interfaces followed by the preferential planar growth, gold prism thin films were thus fabricated on glass substrates.
Co-reporter:Cuicui Qiu, Ran Shang, Yafei Xie, Yanru Bu, Chunyun Li, Houyi Ma
Materials Chemistry and Physics 2010 120(2–3) pp: 323-330
Publication Date(Web):
DOI:10.1016/j.matchemphys.2009.11.014
Co-reporter:Caixia Xu, Yan Zhang, Liqin Wang, Liqiang Xu, Xiufang Bian, Houyi Ma and Yi Ding
Chemistry of Materials 2009 Volume 21(Issue 14) pp:3110
Publication Date(Web):June 29, 2009
DOI:10.1021/cm900244g
We describe the fabrication of novel PdCu bimetallic nanocomposites with hierarchically hollow structures through a simple galvanic replacement reaction using dealloyed nanoporous copper (NPC) as both a template and reducing agent. The reaction process was monitored by UV−vis absorbance spectra and X-ray diffraction (XRD), which clearly demonstrate a structure evolution from NPC precursor to a Pd-rich PdCu alloy structure upon the completion of the reaction. Structure characterization by means of transmission electron microscope (TEM) and scanning electron microscope (SEM) indicates that the replacement reaction between NPC and [PdCl4]2− solution results in a nanotubular mesoporous structure with a nanoporous shell, which is comprised of interconnected alloy nanoparticles with size around 3 nm. The resulted PdCu nanostructure shows superior activity toward oxygen reduction reaction (ORR) with a half-wave potential at 0.840 V, which is significantly better than that of the commercial Pt/C catalyst.
Co-reporter:Zhaona Liu, Lihui Huang, Lili Zhang, Houyi Ma, Yi Ding
Electrochimica Acta 2009 Volume 54(Issue 28) pp:7286-7293
Publication Date(Web):1 December 2009
DOI:10.1016/j.electacta.2009.07.049
Nanoporous Au–Ag alloys with different Ag content were prepared by selective dissolution of Ag from Au42Ag58 alloy samples in HNO3 solutions. With gradual dissolution of Ag component, the corroded Au–Ag alloy samples display typical bicontinuous nanoporous structures after dealloying for more than 10 min. The as-prepared nanostructured Au–Ag alloys exhibit obviously enhanced catalytic activity towards the electrooxidation of d-glucose as compared with the uncorroded Au42Ag58 alloy. It is of interest that the existence of a tiny amount of silver in the corroded Au–Ag alloys is very advantageous to enhancing their catalytic activity for the electrooxidation of glucose. The new finding was confirmed by the significant enhancement of the catalytic activity of a nanoporous gold (NPG) electrode after modification with a monolayer of Ag atoms underpotentially deposited (UPD). The nanoporous Au–Ag alloys with appropriate amount of Ag and the NPGs modified with Ag UPD monolayers are thus expected to be promising electrocatalysts for the development of glucose sensors and glucose fuel cells.
Co-reporter:Zhaona Liu, Junguo Du, Cuicui Qiu, Lihui Huang, Houyi Ma, Dazhong Shen, Yi Ding
Electrochemistry Communications 2009 Volume 11(Issue 7) pp:1365-1368
Publication Date(Web):July 2009
DOI:10.1016/j.elecom.2009.05.004
Nanoporous gold (NPG) with uniform pore sizes and ligaments was prepared by a simple dealloying method. The as-prepared NPG samples were used as the working electrodes to investigate the redox behavior of p-nitrophenol (p-NP) by cyclic voltammetry (CV). Quite different from the voltammetric behavior of polycrystalline gold electrode, the CV profiles of NPG display a pair of nearly symmetric redox waves which are ascribed to the reaction of 4-(hydroxyamino)phenol/4-nitrosophenol couple. It is interesting that this pair of redox waves are hardly affected by the isomers of p-NP; and moreover, their peak areas are linear with the concentration of p-NP in the range from 0.25 to 10 mg dm−3. Because of high sensitivity and good selectivity, NPG is expected to act as a promising electrochemical sensor material for detecting trace p-NP in wastewaters.
Co-reporter:Pengpeng Liu, Xingbo Ge, Rongyue Wang, Houyi Ma and Yi Ding
Langmuir 2009 Volume 25(Issue 1) pp:561-567
Publication Date(Web):December 8, 2008
DOI:10.1021/la8027034
Ultrathin Pt films from one to several atomic layers are successfully decorated onto nanoporous gold (NPG) membranes by utilizing under potential deposition (UPD) of Cu onto Au or Pt surfaces, followed by in situ redox replacement reaction (RRR) of UPD Cu by Pt. The thickness of Pt layers can be controlled precisely by repeating the Cu−UPD−RRR cycles. TEM observations coupled with electrochemical testing suggest that the morphology of Pt overlayers changes from an ultrathin epitaxial film in the case of one or two atomic layers to well-dispersed nanoislands in the case of four and more atomic layers. Electron diffraction (ED) patterns confirm that the as-prepared NPG−Pt membranes maintain a single-crystalline structure, even though the thickness of Pt films reaches six atomic layers, indicating the decorated Pt films hold the same crystallographic relationship to the NPG substrate during the entire fabrication process. Due to the regular modulation of Pt utilization, the electrocatalytic activity of NPG−Pt exhibits interesting surface structure dependence in methanol, ethanol, and CO electrooxidation reactions. These novel bimetallic nanocatalysts show excellent electrocatalytic activity and much enhanced poison tolerance as compared to the commercial Pt/C catalysts. The success in the fabrication of NPG−Pt-type materials provides a new path to prepare electrocatalysts with ultralow Pt loading and high Pt utilization, which is of great significance in energy-related applications, such as direct alcohol fuel cells (DAFCs).
Co-reporter:Yongli Jiao, Deli Wu, Houyi Ma, Cuicui Qiu, Jintao Zhang, Luming Ma
Electrochemistry Communications 2008 Volume 10(Issue 10) pp:1474-1477
Publication Date(Web):October 2008
DOI:10.1016/j.elecom.2008.07.038
The nanostructured Pd thin films prepared via cyclic voltammetric deposition method are proved to be a promising electrocatalyst for electrochemical reductive dechlorination of carbon tetrachloride (CT). The use of as-prepared Pd thin films as the working electrode material provides a possibility to separately study the role of various forms of hydrogen in the dechlorination reactions. Electrochemical characterization and gas chromatography analysis clearly indicate for the first time that the adsorbed hydrogen has excellent ability to remove CT from acidic solutions through the surface reaction with the chemisorbed CT molecules, which is of fundamental importance to have a better understanding of the reaction mechanism of electrochemical dechlorination.
Co-reporter:Jintao Zhang, Houyi Ma, Dongju Zhang, Pengpeng Liu, Fang Tian and Yi Ding
Physical Chemistry Chemical Physics 2008 vol. 10(Issue 22) pp:3250-3255
Publication Date(Web):17 Apr 2008
DOI:10.1039/B718192B
A tiny amount of Pt was deposited in a quasi-two-dimensional form onto the nanoporous gold (NPG) substrate through a simple immersion–electrodeposition (IE) method, forming nanostructured bimetallic Pt–Au catalysts. Such Pt–Au nanostructures have much higher structural stability than the bare NPG; moreover, they exhibit better catalytic activity and stronger poison resistance than commercial Pt–Ru catalysts because of the synergistic effect of the bimetallic compositions.
Co-reporter:Jintao Zhang, Cuicui Qiu, Houyi Ma and Xiuyu Liu
The Journal of Physical Chemistry C 2008 Volume 112(Issue 36) pp:13970-13975
Publication Date(Web):2017-2-22
DOI:10.1021/jp804828k
Cobalt thin films composed of a large number of nanopetals were fabricated on the glassy carbon (GC) substrate by cyclic voltammetric deposition of Co2+ ions on a glass carbon electrode (GCE). The hierarchical Co nanostructures were further used as the sacrificial template to acquire Pd (or Pt) thin film electrocatalysts with hierarchical architectures through the galvanic replacement reaction between Co nanopetals and chloropalladite (or tetrachloroplatinate). The as-prepared Pd (or Pt) thin films contain quantities of nanoparticles and many hollow Pd aggregates in the range of submicrometer to micrometer scale. The hollow Pd aggregates were found to burst in acidic solutions at potentials more negative than the hydrogen evolution potential since Pd absorbed too much hydrogen. As an electrocatalyst for the formic acid oxidation, the Pd thin films presented much higher catalytic activity than the Pt thin films with a similar architecture. An important reason is that the formic acid oxidation at the Pd nanostructures proceeds via a non-CO reaction pathway, while the reaction at the Pt nanostructures involves formation of CO-adsorbed species, which has been confirmed by the CO stripping voltammetric curves on Pd or Pt thin films. The as-prepared Pd thin films with hierarchical architectures are expected to be a promising electrocatalyst in direct formic acid fuel cells (DFAFCs).
Co-reporter:Jintao Zhang, Minghu Huang, Houyi Ma, Fang Tian, Wei Pan, Shenhao Chen
Electrochemistry Communications 2007 Volume 9(Issue 6) pp:1298-1304
Publication Date(Web):June 2007
DOI:10.1016/j.elecom.2007.01.038
Nanostructured Pd thin films are directly formed on polycrystalline Pt and Au substrates in the absence of hard and soft templates by using a cyclic potential sweep technique, which is confirmed by both SEM observation and their unusual cyclic voltammetric characteristics in H2SO4 solution. Interestingly, the bimetallic electrodes obtained after the deposition of ultrathin Pd films onto Pt and Au substrates display much higher catalytic activity towards the electro-oxidation of methanol than the bulk Pt electrode. Besides, it is found that the foreign metal substrate has great influence on the electro-catalytic behavior of the Pd films.
Co-reporter:Feifei Yong, Houyi Ma, Xuning Wang, Xingli Feng, Shaoxin Huang, Jianzhuang Jiang, Shenhao Chen
Electrochimica Acta 2006 Volume 51(Issue 18) pp:3743-3751
Publication Date(Web):5 May 2006
DOI:10.1016/j.electacta.2005.10.049
Bis(octakis(octyloxy) phthalocyaninato) europium(III) (Eu[Pc(OC8H17)8]2) adlayers were self-assembled on the gold surface by means of an improved self-assembling technique. The cyclic voltammograms (CVs) of the Eu[Pc(OC8H17)8]2-modified single-crystalline and poly-crystalline gold electrodes in perchloric acid displayed two pairs of redox waves due to the successive removal or addition of electrons from or to the ligand-based orbitals. The effect of Eu[Pc(OC8H17)8]2 adlayers on the electron transfer rate at electrode/solution interface was investigated by using Fe(CN)63−/4− couple as the redox probe. The redox behavior of Eu[Pc(OC8H17)8]2 adlayers and their accelerating effect on the electron transfer are closely associated with the electronic delocalization of rare earth sandwich complexes. However, in most cases, the Eu[Pc(OC8H17)8]2 adlayers were found to have inhibition role to complicated electrochemical reactions taking place on the gold surface, such as the gold substrate oxidation, the electrochemical reduction of oxygen, the electrochemical oxidation of ascorbic acid (Vitamin C) and the underpotential deposition (UPD) of silver.
Co-reporter:Houyi Ma Dr.;Xingli Feng;Shaoxin Huang;Xiaokai Zhang ;Fang Tian;Feifei Yong;Wei Pan;You Wang Dr.;Shenhao Chen Dr.
ChemPhysChem 2006 Volume 7(Issue 2) pp:333-335
Publication Date(Web):6 FEB 2006
DOI:10.1002/cphc.200500398
Building blocks: Poly(N-vinylpyrrolidone)-protected gold nanoparticles synthesized electrochemically were used as “building blocks” to construct varieties of nanostructures (see figure), including well-defined nanorings, single-crystal films and dense particle films.
Co-reporter:Houyi Ma Dr.;Yongli Jiao;Bingsheng Yin;Shuyun Wang ;Shiyong Zhao Dr.;Shaoxin Huang;Wei Pan;Shenhao Chen Dr.;Fanjun Meng Dr.
ChemPhysChem 2004 Volume 5(Issue 5) pp:
Publication Date(Web):14 MAY 2004
DOI:10.1002/cphc.200301007
Stretching shapes structures: The interaction between poly(N-vinylpyrrolidone) (PVP) and sodium dodecyl benzene sulfonate (SDBS) can make the PVP coil polyvinyl skeleton stretch to a considerable degree. Silver nanoparticles produced by photoreduction are anchored onto the backbone of PVP (see graphic); they then spontaneously organize into one-dimensionally ordered nanoaggregates along the stretched PVP chain.
Co-reporter:H.Y. Ma, C. Yang, S.H. Chen, Y.L. Jiao, S.X. Huang, D.G. Li, J.L. Luo
Electrochimica Acta 2003 Volume 48(Issue 28) pp:4277-4289
Publication Date(Web):15 December 2003
DOI:10.1016/j.electacta.2003.08.003
1-Octadecanethiol (C18SH) monolayers were self-assembled on the fresh and active copper surface pretreated by nitric acid etching method. The surface properties of the alkanethiol-modified copper electrode in halide-containing solutions were characterized systematically by using several electrochemical methods, including polarization curves, cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN). The results show that C18SH self-assembled monolayers (SAMs) onto copper provide a flexible method that can protect the underlying copper against corrosion. With the immersion time of SAMs-coated copper electrode in NaCl and HCl corrosive solutions increasing, a slow loss of corrosion protection ability of SAMs indicates dynamic processes occurring at the electrode/solution interface and in the monolayers, such as expansion of the defects and transport of corrosive ions through defects of SAMs. Electrochemical noise (EN) is employed to detect the alkanethiol-modified copper surfaces immersed in HCl solution. This observation suggests the pitting process associate with dynamic processes in the 1-octadecanethiol layer.
Co-reporter:Houyi Ma, Shenhao Chen, Bingsheng Yin, Shiyong Zhao, Xiangqian Liu
Corrosion Science 2003 Volume 45(Issue 5) pp:867-882
Publication Date(Web):May 2003
DOI:10.1016/S0010-938X(02)00175-0
The inhibitive action of the four surfactants, cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate, sodium oleate and polyoxyethylene sorbitan monooleate (TWEEN-80), on the corrosion behavior of copper was investigated in aerated 0.5 mol dm−3 H2SO4 solutions, by means of electrochemical impedance spectroscopy. These surfactants acted as the mixed-type inhibitors and lowered the corrosion reactions by blocking the copper surface through electrostatic adsorption or chemisorption. The inhibitor effectiveness increased with the exposure time to aggressive solutions, reached a maximum and then decreased, which implies the orientation change of adsorbed surfactant molecules on the surface. CTAB inhibited most effectively the copper corrosion among the four surfactants. The copper surface was determined to be positively charged in sulfuric acid solutions at the corrosion potential, which is unfavourable for electrostatic adsorption of cationic surfactant, CTAB. The reason why CTAB gave the highest inhibition efficiency was attributed to the synergistic effect between bromide anions and positive quaternary ammonium ions. C16H33N(CH3)4+ ions may electrostatically adsorbed on the copper surface covered with primarily adsorbed bromide ions. On the basis of the variation of impedance behaviors of copper in the surfactant-containing solutions with the immersion time, the adsorption model of the surfactants on the copper surface was proposed.
Co-reporter:H.Y. Ma, C. Yang, B.S. Yin, G.Y. Li, S.H. Chen, J.L. Luo
Applied Surface Science 2003 Volume 218(1–4) pp:144-154
Publication Date(Web):30 September 2003
DOI:10.1016/S0169-4332(03)00573-7
Abstract
The self-assembled monolayers (SAMs) of three n-alkanethiols, 1-octadecanethiol (C18SH), 1-dodecanethiol (C12SH), and 1-hexanethiol (C6SH), were formed on the fresh copper surface pretreated by nitric acid etch. The surface properties of the alkanethiol modified copper electrode in chloride-containing solutions were electrochemically characterized. The polarization measurements have shown that alkanethiol SAMs onto copper were able to protect effectively the underlying copper against corrosion. The cyclic voltammetric results, together with FT-IR measurements, showed that alkanethiol SAMs had quite good anodic inhibition at the lower anodic potentials, but this inhibition action gradually lost because of removal of SAMs from the copper substrate with the increase of anodic potentials. Alkanethiol SAMs were proved to be defective by scanning Kelvin probe (SKP) measurements. Electrochemical noise (EN) experiments have shown that SAMs-covered copper electrode suffered pitting attack in HCl solutions. The formation mechanism of pits was explained in this paper.
Co-reporter:Hou-Yi Ma;Bing-Sheng Yin;Gui-Yan Li;Wen-Juan Guo;Shen-Hao Chen;Kai Tang
Chinese Journal of Chemistry 2003 Volume 21(Issue 10) pp:
Publication Date(Web):26 AUG 2010
DOI:10.1002/cjoc.20030211015
Anodic polarization behaviors of iron in pure H2SO4 and three mixed acidic solutions, H2SO4 + NaCl, H2SO4 + NaNO3 and H2SO4+ NaCl + NaNO3, were investigated. The potentiodynamic sweep curves showed that the current densities rose and dropped irregularly in H2SO4 + NaCl solution at the more anodic potentials since the iron surface suffered pitting attack in the solution, but the pitting corrosion was inhibited effectively in the presence of nitrate ions. The surface morphological measurements indicated that pits appeared on the iron surface in H2SO4 + NaCl solution and only a few unobvious corrosion spots were observed in H2SO4 + NaCl + NaNO3 solution after the iron electrode was potentiostatically polarized at 1.3 V. The oscillatory properties of iron are associated with the susceptibility of the iron to pitting. In H2SO4 + NaCl solution, the regular potentiostatic current oscillations gradually evolved into the irregular current fluctuations due to occurrence of the pitting; whereas in H2SO4 + NaCl + NaNO3 solution, the current oscillations took place regularly, like the oscillatory behavior in the pure H2SO4 solution. Thus, when the higher the oscillatory frequency, the more irregular oscillatory process and the more sensitive to pitting iron occurred.
Co-reporter:Yongli Jiao, Cuicui Qiu, Lihui Huang, Kuixia Wu, Houyi Ma, Shenhao Chen, Luming Ma, Deli Wu
Applied Catalysis B: Environmental (7 September 2009) Volume 91(Issues 1–2) pp:434-440
Publication Date(Web):7 September 2009
DOI:10.1016/j.apcatb.2009.06.012
Co-reporter:Wenjing Li, Houyi Ma, Lihui Huang and Yi Ding
Physical Chemistry Chemical Physics 2011 - vol. 13(Issue 13) pp:NaN5568-5568
Publication Date(Web):2011/02/21
DOI:10.1039/C0CP02178D
Well-defined nanoporous palladium (np-Pd) fabricated by a modified electrochemical dealloying procedure is demonstrated to be an excellent electrocatalyst material for reductive degradation of both carbon tetrachloride and chlorobenzene.
Co-reporter:Jintao Zhang, Houyi Ma, Dongju Zhang, Pengpeng Liu, Fang Tian and Yi Ding
Physical Chemistry Chemical Physics 2008 - vol. 10(Issue 22) pp:NaN3255-3255
Publication Date(Web):2008/04/17
DOI:10.1039/B718192B
A tiny amount of Pt was deposited in a quasi-two-dimensional form onto the nanoporous gold (NPG) substrate through a simple immersion–electrodeposition (IE) method, forming nanostructured bimetallic Pt–Au catalysts. Such Pt–Au nanostructures have much higher structural stability than the bare NPG; moreover, they exhibit better catalytic activity and stronger poison resistance than commercial Pt–Ru catalysts because of the synergistic effect of the bimetallic compositions.
Co-reporter:Rongyan Jiang, Congying Cui and Houyi Ma
Physical Chemistry Chemical Physics 2013 - vol. 15(Issue 17) pp:NaN6415-6415
Publication Date(Web):2013/03/04
DOI:10.1039/C3CP44516J
Graphene nanosheets (GNs) were directly used as a type of novel but powerful planar conductive additive in spinel LiMn2O4 (LMO)-based electrodes, to improve the low electronic conductivity of LMO. It was found that the specific capacity and cycling performance of LMO were obviously enhanced when GNs co-existed with acetylene black (AB), a conventional carbon-based conductive agent, at an appropriate weight ratio in the LMO-based electrode (GNs and AB were 5 wt% and 10 wt% of the total weight, respectively). The unusual phenomenon was attributed to the following two reasons: (i) the planar GNs could bridge LMO particles more effectively via a “plane-to-point” conducting mode; (ii) AB particles might serve as the fillings in the electrode and connect the isolated LMO particles to GNs through a “filling effect”, thereby constructing a novel and more effective conducting network. In this way, the synergy effect between the “plane-to-point” conducting mode (due to GNs) and the “filling” mode (due to AB) significantly decreased the charge-transfer resistance of the LMO-based electrode. With the much faster charge-transfer process, the rate performance of LMO was greatly enhanced. In contrast, when GNs were in excess, the effective conducting network was weakened by the agglomeration of GNs and the absence of AB, so the conductivity and the rate performance of LMO were not improved and even decreased.
Co-reporter:Ke Lu, Dan Li, Xiang Gao, Hongxiu Dai, Nan Wang and Houyi Ma
Journal of Materials Chemistry A 2015 - vol. 3(Issue 31) pp:NaN16019-16019
Publication Date(Web):2015/06/30
DOI:10.1039/C5TA04244E
This paper demonstrates how to design and construct an advanced aqueous sodium-ion supercapacitor by using manganous hexacyanoferrate (MnHCF) as the cathode material and Fe3O4/rGO nanocomposites as the anode material. The rational combination of these two materials with neutral aqueous electrolytes provides the devices with an extended voltage of 1.8 V, much higher power density (2183.5 W kg−1) and energy density (27.9 W h kg−1) compared with similar devices reported in the literature. The devices also have good cycling stability with 82.2% capacity retention even after 1000 cycles. More significantly, the supercapacitors are designed with low cost and environmentally benign materials and are more suitable for future large-scale practical applications.
![4-{2-[(5-CHLORO-2-METHOXYPHENYL)SULFONYL]ETHYL}MORPHOLINE HYDROCH<WBR />LORIDE (1:1)](http://img.cochemist.com/ccimg/4000/3991-73-9.png)
![4-{2-[(5-CHLORO-2-METHOXYPHENYL)SULFONYL]ETHYL}MORPHOLINE HYDROCH<WBR />LORIDE (1:1)](http://img.cochemist.com/ccimg/4000/3991-73-9_b.png)
