Co-reporter:Jing-Kai Qin, Dan-Dan Ren, Wen-Zhu Shao, Yang Li, Peng Miao, Zhao-Yuan Sun, PingAn Hu, Liang Zhen, and Cheng-Yan Xu
ACS Applied Materials & Interfaces November 15, 2017 Volume 9(Issue 45) pp:39456-39456
Publication Date(Web):October 20, 2017
DOI:10.1021/acsami.7b10349
ReS2 films are considered as a promising candidate for optoelectronic applications due to their direct band gap character and optical/electrical anisotropy. However, the direct band gap in a narrow spectrum and the low absorption of atomically thin flakes weaken the prospect for light-harvesting applications. Here, we developed an efficient approach to enhance the performance of a ReS2-based phototransistor by coupling CdSe–CdS–ZnS core–shell quantum dots. Under 589 nm laser irradiation, the responsivity of the ReS2 phototransistor decorated with quantum dots could be enhanced by more than 25 times (up to ∼654 A/W) and the rising and recovery time can be also reduced to 3.2 and 2.8 s, respectively. The excellent optoelectronic performance is originated from the coupling effect of quantum dots light absorber and cross-linker ligands 1,2-ethanedithiol. Photoexcited electron–hole pairs in quantum dots can separate and transfer efficiently due to the type-II band alignment and charge exchange process at the interface. Our work shows that the simple hybrid zero- and two-dimensional hybrid system can be employed for photodetection applications.Keywords: 0D−2D hybrid system; exfoliation; photodetector; quantum dots; ReS2;
Co-reporter:Jing-Kai Qin, Wen-Zhu Shao, Cheng-Yan Xu, Yang Li, Dan-Dan Ren, Xiao-Guo Song, and Liang Zhen
ACS Applied Materials & Interfaces May 10, 2017 Volume 9(Issue 18) pp:15583-15583
Publication Date(Web):April 25, 2017
DOI:10.1021/acsami.7b02101
Substitutional doping of transition metal dichalcogenide two-dimensional materials has proven to be effective in tuning their intrinsic properties, such as band gap, transport characteristics, and magnetism. In this study, we realized substitutional doping of monolayer rhenium disulfide (ReS2) with Mo via chemical vapor deposition. Scanning transmission electron microscopy demonstrated that Mo atoms are successfully doped into ReS2 by substitutionally replacing Re atoms in the lattice. Electrical measurements revealed the degenerate p-type semiconductor behavior of Mo-doped ReS2 field effect transistors, in agreement with density functional theory calculations. The p–n diode device based on a doped ReS2 and ReS2 homojunction exhibited gate-tunable current rectification behaviors, and the maximum rectification ratio could reach up to 150 at Vd = −2/+2 V. The successful synthesis of p-type ReS2 in this study could largely promote its application in novel electronic and optoelectronic devices.Keywords: DFT calculations; homojunction; p−n diode; ReS2; substitutional doping;
Co-reporter:Jing Yu;Fei-Xiang Ma;Dr. Yue Du;Pan-Pan Wang; Cheng-Yan Xu; Liang Zhen
ChemElectroChem 2017 Volume 4(Issue 3) pp:594-600
Publication Date(Web):2017/03/01
DOI:10.1002/celc.201600652
AbstractNickel sulfides have been widely employed as high-performance electrocatalysts for the hydrogen evolution reaction (HER) with high activity and low cost, and their performance could be tremendously promoted by elaborate design. Herein, we report a simple solvothermal route for the in situ growth of a three-dimensional network structure of Sn-doped Ni3S2, assembled by using ultrathin nanosheets on Ni foam. The ultrathin nanosheets with thicknesses of approximately 5–9 nm could provide more exposed active edges and a shorter electron transfer path. The Sn-doped sample exhibited efficient and durable electrocatalytic HER activity both in acid and alkaline conditions, much better than that of undoped Ni3S2 nanorods. Nyquist plots indicated that the electrochemical impendence reduced with the introduction of elemental Sn, which was another critical factor for the enhanced catalytic performance.
Co-reporter:Yan-ge Yu, Jing Zhong, Jindun Liu, Guo-Xiang Zhou, Lan-Xiang Lv, Cheng-Yan Xu, Nikhil Koratkar
Composites Science and Technology 2017 Volume 146(Volume 146) pp:
Publication Date(Web):7 July 2017
DOI:10.1016/j.compscitech.2017.04.001
Hot/cold pressing is a very common process in powder metallurgy and polymer industry, in which powders are compacted at a temperature/pressure high enough to induce sintering and creeping processes, and make the materials much denser and stronger. In this study, we extent this strategy to the synthesis of carbon nanotube (CNT) nanocomposites, yet with the high compressive stress generated naturally during the ultra-filtration process. Employing dead filtration, which is traditionally employed to extract solids from solution in water treatment process, we fabricate CNTs/PVA nanocomposites with high CNTs loading. It was found that this process not only greatly accelerates the filtration, but also generates significant in-situ pressure on the nanocomposites during its formation. Such pressure can compress the nanocomposites in-situ from the very onset of the formation of the nanocomposites and at molecular scale, which makes the nanocomposites densely compacted and eventually translates to very high mechanical properties even at high CNTs concentrations of up to ∼90 vol%. The tensile strength and Young's modulus can be increased by 435% and 859%, respectively, and the toughness is comparable with the nacre at similar content of inorganic constituent.
Co-reporter:Jing-Kai Qin;Wen-Zhu Shao;Yang Li;Dan-Dan Ren;Xiao-Guo Song;Liang Zhen
RSC Advances (2011-Present) 2017 vol. 7(Issue 39) pp:24188-24194
Publication Date(Web):2017/05/03
DOI:10.1039/C7RA01748K
Rhenium disulfide (ReS2) has attracted scientists' attention for its unique physical properties and potential applications in high-efficiency photodetector devices. Although lots of works have been done to obtain high-quality ReS2 nanoflakes, in-plane uniform growth is still challenging due to its unique decoupling property between layers. In this work, we successfully realized the epitaxial growth of continuous monolayer ReS2 films on mica substrate by chemical vapour deposition (CVD). By prolonging the growth time, continuous multilayer ReS2 films can also be obtained. The growth mechanism of ReS2 films is proposed based on Stranski–Krastanov theory. Filed effect transistors (FETs) based on multilayer ReS2 films exhibit typical n-type semiconducting behaviour with a carrier density of 0.27 cm2 V−1 s−1 and ON/OFF ratio of about 4 × 103. The photoresponsivity of the phototransistor could reach up to 0.98 A W−1 with a light intensity of 0.56 mW cm−2, suggesting that ReS2 is a promising material for electronic and optoelectronic applications.
Co-reporter:Jing Yu;Qianqian Li;Na Chen;Yuan Li;Heguang Liu;Liang Zhen;Vinayak P. Dravid;Jinsong Wu
Journal of Materials Chemistry A 2017 vol. 5(Issue 8) pp:3981-3986
Publication Date(Web):2017/02/21
DOI:10.1039/C6TA10303K
The development of highly efficient water oxidation electrocatalysts made of low-cost and earth-abundant elements is a prerequisite. Sluggish kinetics in the reaction of water splitting is the major obstacle. Herein, we report the fabrication of a robust catalyst for the oxygen evolution reaction (OER) based on the hybrid of N-doped graphene coupled metallic NiSe2 pyramids (NG/NiSe2/NF). The reaction kinetics has greatly increased due to the synergistic effects of the two components providing enhanced electroconductibility and increased active sites. The NG/NiSe2/NF electrode exhibits superior water oxidation ability and cycle stability. This approach opens ways to design effective oxygen evolution electrodes.
Co-reporter:Shuang Yang;Bao-You Zhang
Journal of Materials Science: Materials in Electronics 2017 Volume 28( Issue 2) pp:1869-1876
Publication Date(Web):01 October 2016
DOI:10.1007/s10854-016-5738-0
Two-dimensional materials, such graphene and transition metal dichalcogenides with layered structures, and other non-layered materials, have found broad applications in optoelectronics, energy storage and photocatalysis, utilizing the unique properties arising from the two-dimensional characteristics. In this work, we report the solvothermal synthesis of uniform InOOH nanosheets with average length of c.a. 1.5 μm, width of c.a. 500 nm, and thickness of c.a. 60 nm. The obtained InOOH nanosheets are characterized by X-ray diffraction, scanning electron microscope and transmission electron microscope. The possible growth mechanism of the InOOH nanosheets was discussed. Photocatalytic and photoelectrochemical experiments indicated that the InOOH nanosheets present enhanced photocatalytic activity for the degradation of Rhodamine B under UV light irradiation, which can be ascribed to its high BET surface area as well as enhanced electron–hole separation originated from the two-dimensional morphological characteristics.
Co-reporter:Yi Pei, Qing Chen, Yu-Chen Xiao, Li Liu, Cheng-Yan Xu, Liang Zhen, Graeme Henkelman, Guozhong Cao
Nano Energy 2017 Volume 40(Volume 40) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.nanoen.2017.08.054
•Overall phase transitions were determined by designed ex-/in-situ XRD measurements.•Structure evolutions were revealed by density functional theory (DFT) calculations.•Thermodynamic and dynamic priority were explored by experiments and calculations.•Dynamic priority was utilized to control constitution of LLO/spinel composites.xLi2MnO3·(1−x)LiMO2 (LLO)/spinel nanocomposites are of substantial interest as cathodes with high capacity and enhanced conductivity. However, their electrochemical properties are significantly influenced by the complex phase constitutions, and undesired by-products such as rock salt phase could not be efficiently avoided. By ex-/in-situ XRD, we revealed the three phase transitions during the decomposition reaction of spinel phase, namely, Li-rich spinel (SL) to LLO (L), normal spinel (SN) to rock salt (R) and rock salt to LLO. Density functional theory calculations suggest that Li migrates from the 8a tetrahedral site to the interstitial 16c octahedral site as oxygen is released from SL and SN, forming quasi-Li2MnO3 and quasi-rock salt crystals, respectively. The dynamic priority of each reaction determined by experiments and calculations was utilized to design the LLO/spinel composites, and a composite with more spinel phase (7.6%) demonstrated high capacity retention at high rates. Our study sheds light on the mechanism of phase transitions among the spinel-layered-rock salt system and reveal the thermodynamic and dynamic priority of each reaction, facilitating the rational design of LLO/spinel composites.Download high-res image (289KB)Download full-size image
Co-reporter:Yang Li;Jing-Kai Qin;Wei Feng;Jia-Ying Wang;Siqi Zhang;Lai-Peng Ma;Jian Cao;Ping An Hu;Wencai Ren;Liang Zhen
Advanced Functional Materials 2016 Volume 26( Issue 2) pp:293-302
Publication Date(Web):
DOI:10.1002/adfm.201503131
The behavior of excitons in van der Waals (vdWs) heterostructures depends on electron–electron interactions and charge transfer at the hetero-interface. However, what still remains to be unraveled is to which extent the carrier densities of both counterparts and the band alignment in the vdWs heterostructures determine the photoluminescence properties. Here, we systematically study the photoluminescence properties of monolayer MoS2/graphene heterostructures by modulating the carrier densities and contact barrier at the interface via electrochemical gating. It is shown that the PL intensities of excitons can be tuned by more than two orders of magnitude, and a blue-shift of the exciton peak of up to 40 meV is observed. By extracting the carrier density of MoS2 using an electric potential distribution model, and the Schottky barrier using first-principle calculations, we find that the controllable carrier density in MoS2 plays a dominant role in the PL tuning at negative gate bias, whereas the interlayer relaxation of excitons induced by the Schottky barrier has a major contribution at positive gate bias. This is further verified by controlling the tunneling barrier and screening field across MoS2 by inserting self-assembled monolayers (SAMs) at the interface. These findings will benefit to better understand the effect of many-body interactions and hetero-interfaces on the optical and optoelectronic properties in vdWs heterostructures.
Co-reporter:Yang Li;Jing-Kai Qin;Jian Cao;Zhao-Yuan Sun;Lai-Peng Ma;Ping An Hu;Wencai Ren;Liang Zhen
Advanced Functional Materials 2016 Volume 26( Issue 24) pp:4319-4328
Publication Date(Web):
DOI:10.1002/adfm.201505412
Transition metal dichalcogenides van der Waals (vdWs) heterostructures present fascinating optical and electronic phenomena, and bear tremendous significance for electronic and optoelectronic applications. As the significant merits in vdWs heterostructures, the interlayer relaxation of excitons and interlayer coupling at the heterointerface reflect the dynamic behavior of charge transfer and the coupled electronic/structural characteristics, respectively, which may give rise to new physics induced by quantum coupling. In this work, upon tuning the photoluminescence (PL) properties of WSe2/graphene and WSe2/MoS2/graphene heterostructures by virtue of electric field, it is demonstrated that the interlayer relaxation of excitons at the heterointerface in WSe2/graphene, which is even stronger than that in MoS2/graphene and WSe2/MoS2 , plays a dominant role in PL tuning in WSe2/graphene, while the carrier population in WSe2 induced by electric field has a minor contribution. In addition, it is discovered that the interlayer coupling between monolayer WSe2 and graphene is enhanced under high electric field, which breaks the momentum conservation of first order Raman-allowed phonons in graphene, yielding the enhanced Raman scattering of defects in graphene. The interplay between electric field and vdWs heterostructures may provide versatile approaches to tune the intrinsic electronic and optical properties of the heterostructures.
Co-reporter:Zhao-Hua Miao, Hui Wang, Huanjie Yang, Zhenglin Li, Liang Zhen, and Cheng-Yan Xu
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 25) pp:15904-15910
Publication Date(Web):June 9, 2016
DOI:10.1021/acsami.6b03652
Carbon nanomaterials with small size and unique optical properties have attracted intensive interest for their promising biomedical applications. In this work, glucose-derived carbonaceous nanospheres (CNSs) with high photothermal conversion efficiency up to 35.1% are explored for the first time as a novel carbon-based theranostic agent. Different from most other carbon nanomaterials, the obtained CNSs are highly biocompatible and nontoxic because of their intrinsic hydrophilic property and the use of glucose as raw materials. Under near-infrared laser irradiation (808 nm, 6 W cm–2) for 10 min, less than 15% of PC-3M-IE8 cells exposed to CNSs aqueous dispersions (0.16 mg/mL) remained alive. After intravenous administration of CNSs aqueous dispersions into nude mice, the photoacoustic intensity of the tumor region is about 2.5 times higher than that of preinjection. These results indicate that CNSs are suitable for simultaneous photoacoustic imaging and photothermal ablation of cancer cells and can serve as promising biocompatible carbon-based agents for further clinical trials.
Co-reporter:Jing Yu, Qianqian Li, Na Chen, Cheng-Yan Xu, Liang Zhen, Jinsong Wu, and Vinayak P. Dravid
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 41) pp:27850
Publication Date(Web):October 3, 2016
DOI:10.1021/acsami.6b10552
Low-cost and efficient electrocatalysts for overall water splitting are in high demand for a wide range of applications across renewable and clean energy. Here, we report a simple one-step synthesis of a three-dimensional (3D) carbon-coated Ni8P3 nanosheet array as bifunctional catalyst for both hydrogen evolution reactions (HER) and oxygen evolution reactions (OER). The nanosheet array possesses low overpotentials, high current densities, and small Tafel slopes in both HER and OER and shows high electrocatalytic activities and long-term stability. The carbon layer with high electric conductivity serves not only as a protective layer to prevent Ni8P3 dissolution but also as an active layer to decrease the electrocatalysis overpotential. The nanosheet array has HER outstanding activity in both acid and alkaline media. Its superior performance in OER can be due to the synergistic interaction at the Ni8P3/NiOx heterojunction. Furthermore, cell voltage as low as 1.65 V can achieve 10 mA cm–2 current density for full water splitting in an alkaline water electrolyzer, indicating potential application of C@ Ni8P3 as bifunctional catalyst for clean and renewable energy utilization.Keywords: carbon coating; nanosheets array; nickel phosphide; overall water splitting; synergistic effect
Co-reporter:Pan-Pan Wang, Yan-Xin Yao, Cheng-Yan Xu, Long Wang, Wen He, Liang Zhen
Ceramics International 2016 Volume 42(Issue 13) pp:14595-14600
Publication Date(Web):October 2016
DOI:10.1016/j.ceramint.2016.06.075
Abstract
Self-standing V2O5 nanobelt electrode free of binders, conductive carbon or current collectors was successfully prepared via a simple one-step hydrothermal reaction. The length of V2O5 nanobelts was up to several hundreds micrometers and the thickness was around 40 nm. Ultralong nanobelts as building blocks and internal voids provide a robust mechanical flexibility and shortened ion/electron transport pathway. The self-standing electrode delivered an initial specific capacity of 127.4 mA h g−1 at a current density of 60 mA g−1 and exhibited excellent cycling stability with capacity retention up to 89.8% after 200 cycles. The outstanding cycling performance can be attributed to the excellent network stability, shortened Li-ion diffusion pathway and the high surface area between electrolyte/electrode interfaces.
Co-reporter:Zhao-Hua Miao, Pan-Pan Wang, Yu-Chen Xiao, Hai-Tao Fang, Liang Zhen, and Cheng-Yan Xu
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 49) pp:
Publication Date(Web):November 18, 2016
DOI:10.1021/acsami.6b13046
Molybdenum disulfide with a layered structure and high theoretical capacity is attracting extensive attention for high-performance lithium-ion batteries. In this study, a simple and scalable method by freeze-drying of (NH4)2MoS4 and dopamine mixed solutions along with subsequent calcination is developed to realize the self-assembly of hierarchical MoS2/carbon composite nanosheets via the effect of dopamine-induced morphology transformation, in which ultrasmall few-layer MoS2 nanosheets were homogeneously embedded into a N-doped carbon framework (denoted as MoS2@N-CF). The embedded ultrasmall MoS2 nanosheets (∼5 nm in length) in the composites consist of less than five layers with an expanded interlayer spacing of the (002) plane. When tested as anode materials for rechargeable Li-ion batteries, the obtained MoS2@N-CF nanosheets exhibit outstanding electrochemical performance in terms of high specific capacity (839.2 mAh g–1 at 1 A g–1), high initial Coulombic efficiency (85.2%), and superior rate performance (702.1 mAh g–1 at 4 A g–1). Such intriguing electrochemical performance was attributed to the synergistic effect of uniform dispersion of few-layer MoS2 into the carbon framework, expanded interlayer spacing, and enhanced electronic conductivity in the unique hierarchical architecture. This work provides a simple and effective strategy for the uniform integration of MoS2 with carbonaceous materials to significantly boost their electrochemical performance.Keywords: carbon framework; dopamine; expanded interlayer; lithium-ion batteries; molybdenum disulfide;
Co-reporter:Zhao-Hua Miao, Hui Wang, Huanjie Yang, Zheng-Lin Li, Liang Zhen, and Cheng-Yan Xu
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 31) pp:16946
Publication Date(Web):July 21, 2015
DOI:10.1021/acsami.5b06265
Theranostic agents for magnetic resonance imaging (MRI) guided photothermal therapy have attracted intensive interest in cancer diagnosis and treatment. However, the development of biocompatible theranostic agents with high photothermal conversion efficiency and good MRI contrast effect remains a challenge. Herein, PEGylated Mn2+-chelated polydopamine (PMPDA) nanoparticles were successfully developed as novel theranostic agents for simultaneous MRI signal enhancement and photothermal ablation of cancer cells, based on intrinsic manganese-chelating properties and strong near-infrared absorption of polydopamine nanomaterials. The obtained PMPDA nanoparticles showed significant MRI signal enhancement for both in vitro and in vivo imaging. Highly effective photothermal ablation of HeLa cells exposed to PMPDA nanoparticles was then achieved upon laser irradiation for 10 min. Furthermore, the excellent biocompatibility of PMPDA nanoparticles, because of the use of Mn2+ ions as diagnostic agents and biocompatible polydopamine as photothermal agents, was confirmed by a standard MTT assay. Therefore, the developed PMPDA nanoparticles could be used as a promising theranostic agent for MRI-guided photothermal therapy of cancer cells.Keywords: cancer cells; magnetic resonance imaging; photothermal ablation; polydopamine nanoparticles; theranostic agent
Co-reporter:Pan-Pan Wang, Cheng-Yan Xu, Wang-Da Li, Long Wang, Liang Zhen
Electrochimica Acta 2015 Volume 169() pp:440-446
Publication Date(Web):1 July 2015
DOI:10.1016/j.electacta.2015.04.084
The low temperature electrochemical behavior of β-LixV2O5 as cathode material was investigated by galvanostatic charge/discharge test and electrochemical impedance spectroscopy. The β-LixV2O5 cathode exhibited unusual high capacity retention ratio upon 100 cycles under subzero temperatures: 88.6% at −40 °C, 79.5% at −20 °C, and 82.3% at 0 °C while only 55.0% at room temperature. Electrochemical impedance spectroscopy results indicate that the charge-transfer resistance increases sharply and the lithium diffusion coefficient decreases gradually as temperature dropping to −40 °C. According to Randles plot and Arrhenius equation, the activation energies for charge-transfer and solid-state lithium diffusion at 20% state of charge are 43.28 and 47.96 kJ mol−1, respectively, suggesting that the electrochemical process dynamics of the β-LixV2O5 electrode is controlled by the sluggish charge-transfer kinetics as well as solid-state ionic diffusion.
Co-reporter:Fei-Xiang Ma, Pan-Pan Wang, Cheng-Yan Xu, Jing Yu, Hai-Tao Fang and Liang Zhen
Journal of Materials Chemistry A 2014 vol. 2(Issue 45) pp:19330-19337
Publication Date(Web):30 Sep 2014
DOI:10.1039/C4TA03008G
Self-stacked CuFe2O4–Fe2O3 porous nanosheets were prepared via a facile polyol-mediated route followed by calcination. Because of its highly porous structures and good electrical and ion conductivity of the well-dispersed CuFe2O4 phase in the matrix, the hybrid material exhibits high specific capacity of 910 mA h g−1 at 0.5 C after 200 cycles, superior capacity retention (0.02% capacity loss per cycle) and good rate capability (417 mA h g−1 at 4 C) as a promising anode material for Li-ion batteries.
Co-reporter:Jing Yu, Cheng-Yan Xu, Fei-Xiang Ma, Sheng-Peng Hu, Yu-Wei Zhang, and Liang Zhen
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 24) pp:22370
Publication Date(Web):November 20, 2014
DOI:10.1021/am506396z
Graphene-like two-dimensional layered materials have attracted quite a lot of interest because of their sizable band gaps and potential applications. In this work, monodisperse tin disulfide (SnS2) nanosheets were successfully prepared by a simple solvothermal procedure in the presence of polyvinylpyrrolidone (PVP). Large PVP molecules absorbing on (001) facets of SnS2 would inhibit crystal growth along [001] orientation and protect the product from agglomeration. The obtained SnS2 nanosheets have diameters of ca. 0.8–1 μm and thicknesses of ca. 22 nm. Different experiment parameters were carried out to investigate the transformation of phase and morphology. The formation mechanism was proposed according to the time-dependent experiments. SnS2 nanosheets exhibit high photocatalytic H2 evolution activity of 1.06 mmol h–1 g–1 under simulated sunlight irradiation, much higher than that of SnS2 with different morphologies and P25-TiO2. Moreover, the as-obtained SnS2 nanosheets show excellent photoelectrochemical response performance in visible-light region.Keywords: nanosheets; photocatalytic hydrogen evolution; photoelectrochemical response; solvothermal; tin disulfide
Co-reporter:Sheng-Peng Hu, Cheng-Yan Xu, Fei-Xiang Ma, Lei Cao and Liang Zhen
Dalton Transactions 2014 vol. 43(Issue 22) pp:8439-8445
Publication Date(Web):24 Mar 2014
DOI:10.1039/C3DT53561D
We report the solvothermal synthesis of hierarchical structures of orthorhombic Sb2WO6 and their implementation as a visible-light-driven photocatalyst for the degradation of Rhodamine B. The obtained hierarchical structures constructed by tiny nanosheets are doughnut-like flat ellipsoids with concaves in the centres, and with typical sizes of 1.3 μm in length, 800 nm in width and 400 nm in thickness. The concave characteristics and sizes of Sb2WO6 hierarchical structures can be tuned by adjusting the volume ratio of EG–H2O. Time-dependent experiments reveal that the formation process of concave structures involves the aggregation of nanoparticles to form solid spheres, dissolution–recrystallization to form hierarchical structures subsequently, and an Ostwald ripening process to shape the desired concaves finally. Under visible-light irradiation, complete degradation of Rhodamine B is achieved within 180 min in the presence of Sb2WO6 hierarchical structures, which could be ascribed to the porous structures, high BET surface area (42.58 m2 g−1) and wide absorption in the visible-light region.
Co-reporter:Sheng-Peng Hu, Cheng-Yan Xu, Wen-Shou Wang, Fei-Xiang Ma, Liang Zhen
Ceramics International 2014 Volume 40(Issue 8) pp:11689-11698
Publication Date(Web):September 2014
DOI:10.1016/j.ceramint.2014.03.179
We report a facile template-free solvothermal approach for the synthesis of Bi2WO6 hierarchical structures assembled by porous nanoplates, the unique morphology of which endows the sample with high photocatalytic activity under visible light irradiation. The synthesized Bi2WO6 hierarchical structures have diameters of ~1 μm, and consist of multiple crossed-plates in three-dimensional configuration. A possible three-stage formation mechanism was proposed for the construction of hierarchical structures, and Ostwald ripening was responsible for the formation of meso-pores. The as-prepared Bi2WO6 hierarchical structures exhibited high photocatalytic activity on the degradation of Rhodamine B under visible light irradiation, due to the larger specific surface area (20.4 m2 g−1), unique hierarchical structures with multiple-crossed porous layer and higher crystallinity. A comparison of photocatalytic performance between the hierarchical structures and other samples with different morphologies was performed. The main active species of Bi2WO6 hierarchical structures during a photocatalytic process were determined to be O2− and h+ radicals by dissolving different trapping agents.
Co-reporter:Wang-Da Li, Cheng-Yan Xu, Xiao-Liang Pan, Yu-Dong Huang and Liang Zhen
Journal of Materials Chemistry A 2013 vol. 1(Issue 17) pp:5361-5369
Publication Date(Web):21 Feb 2013
DOI:10.1039/C3TA01609A
LixV2O5 (x ∼ 0.42) nanorods, an overdoped β-phase vanadium oxide bronze with a rigid three-dimensional framework, have been fabricated for the first time via a simple two-step synthetic method. It is found that the δ-type structure of the as-prepared hydrated nanobelts through the hydrothermal route is converted into the tunnel β geometry upon annealing-induced dehydration. After annealing at 600 °C, the β-LixV2O5 nanorods exhibit the desired electrochemical properties: an initial gravimetric discharge capacity of 388.4 mA h g−1 (corresponding to an uptake of ca. 2.68 lithium per cell unit) and a specific energy density of 1039.6 W h kg−1 are achieved within a 2.0 V cut-off voltage at C/20, which decreased to 295.3 mA h g−1 (ca. 2.04 Li/V2O5) and 789.0 W h kg−1 after 50 cycles, respectively. The irreversible formation of ω-LixV2O5 for layered V2O5 cathodes upon deep lithiation is not presented during cell operation, and such improved structural reversibility is attributed to the highly retrievable host framework of the β-Li bronze, as well as further strain relaxation facilitated by the one-dimensional nanostructures. Based on the distinctive crystallographic structure and superior electrochemical properties, this β-lithium vanadium bronze has shown promising potential as a cathode material for secondary lithium-based batteries.
Co-reporter:Xiao-Liang Pan, Cheng-Yan Xu, Da Hong, Hai-Tao Fang, Liang Zhen
Electrochimica Acta 2013 Volume 87() pp:303-308
Publication Date(Web):1 January 2013
DOI:10.1016/j.electacta.2012.09.106
Well-dispersed LiMnPO4 plates with thickness of about 100 nm were synthesized by a facile hydrothermal method at 200 °C for 10 h. The crystalline structure, morphology and microstructure were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The LiMnPO4 electrode exhibits high discharge capacity, good rate capability and high cycling stability. At a 0.05 C rate, the plates delivered a discharge capacity of 139.2 mA h g−1 at 25 °C and 158.7 mA h g−1 at 50 °C. At elevated temperature (50 °C), the plates showed an enhanced rate capability, achieving a discharge capacity of 147.6, 141.4, 133.6, 121.4, and 110.7 mA h g−1 at 0.1, 0.2, 0.5, 1, and 2 C, respectively. Moreover, the plates had good cycling stability, retaining 92% of the initial capacity at 25 °C and 91% at 50 °C over 50 cycles at 0.1 C. The excellent electrochemical performance of this material is attributed to its high specific surface area, large percentage of exposed (0 1 0) facets as well as small thickness along the [0 1 0] direction.Highlights► Well-dispersed LiMnPO4 plates with exposed (0 1 0) facets and thickness of about 100 nm were synthesized by a hydrothermal method. ► The LiMnPO4 plates exhibited a discharge capacity of 139.2 mA h g−1 at 25 °C and 158.7 mA h g−1 at 50 °C, both at a rate of 0.05 C. ► The LiMnPO4 plates showed good cycling stability, retaining 92% of the initial capacity at 0.1 C after 50 cycles.
Co-reporter:Cheng-Yan Xu, Jia Wu, Pei Zhang, Sheng-Peng Hu, Jian-Xun Cui, Zeng-Quan Wang, Yu-Dong Huang and Liang Zhen
CrystEngComm 2013 vol. 15(Issue 17) pp:3448-3454
Publication Date(Web):22 Feb 2013
DOI:10.1039/C3CE27092K
The molten salt synthesis of sodium titanate one-dimensional nanostructures at relatively low temperature (ca. 825 °C) was re-examined in detail to elucidate the roles of various experimental parameters. Two kinds of sodium titanate nanowires, i.e., Na2Ti3O7 and Na2Ti6O13, with almost the same diameters were obtained in the presence of excess sodium oxalate, which also played an important role in enhancing nanowires yield. High calcining temperature favours the formation of Na2Ti6O13-predominant product at high sodium content. The introducing of nonionic surfactant NP-9 not only improves the uniformity of nanowires, but also favours the formation of Na2Ti6O13 phase. The obtained Na2Ti3O7 and Na2Ti6O13 nanowires have good crystallinity and both grow along the [010] crystallographic directions. The synthesized Na2Ti6O13 nanowires exhibited good photocatalytic activity towards the degradation of methyl orange under ultraviolet light irradiation. A humidity sensor based on Na2Ti3O7 nanowires was fabricated and showed good sensing performance at room temperature.
Co-reporter:Sheng-Peng Hu, Cheng-Yan Xu, Liang Zhen
Materials Letters 2013 Volume 95() pp:117-120
Publication Date(Web):15 March 2013
DOI:10.1016/j.matlet.2012.12.058
Bi2WO6 hollow structures consisting of nanoparticles with diameters of 10–20 nm were synthesized by a facile and reproducible solvothermal method in the presence of ethylene glycol. The obtained Bi2WO6 hollow structures exhibit higher photocatalytic activity towards the degradation of Rhodamine B (RhB) under visible-light irradiation, up to 99% within 40 min, which was much higher than P25-TiO2. The enhanced photocatalytic performance could be attributed to their tiny building blocks as well as high BET surface areas (65.04 m2 g−1). The obtained Bi2WO6 hollow structures are chemically stable, and the efficiency remained almost the same after recycled five times, suggesting that Bi2WO6 hollow structures are promising visible-light photocatalyst for practical applications.Graphical abstractBi2WO6 hollow structures consisting of nanoparticles with diameters of 10–20 nm were synthesized by a facile and reproducible solvothermal method. The obtained Bi2WO6 hollow structures exhibit superior visible-light photocatalytic property than P25-TiO2 as well as high cycling performance.Highlights► Bi2WO6 hollow structures were synthesized by a simple and reproducible solvothermal route. ► Compared with P25-TiO2, Bi2WO6 hollow structures show excellent photocatalytic property, and the catalyst shows high cycle performance under visible light irradiation. ► The excellent photocatalytic properties are attributed to their large surface area and small building blocks.
Co-reporter:Yang Li, Cheng-Yan Xu, PingAn Hu, and Liang Zhen
ACS Nano 2013 Volume 7(Issue 9) pp:7795
Publication Date(Web):August 16, 2013
DOI:10.1021/nn402682j
Carrier doping of MoS2 nanoflakes was achieved by functional self-assembled monolayers (SAMs) with different dipole moments. The effect of SAMs on the charge transfer between the substrates and MoS2 nanoflakes was studied by Raman spectroscopy, field-effect transistor (FET) measurements, and Kelvin probe microscope (KFM). Raman data and FET results verified that fluoroalkyltrichlorosilane-SAM with a large positive dipole moment, acting as hole donors, significantly reduced the intrinsic n-doping characteristic of MoS2 nanoflakes, while 3-(trimethoxysilyl)-1-propanamine-SAMs, acting as electron donors, enhanced the n-doping characteristic. The additional built-in electric field at the interface between SiO2 substrates and MoS2 nanoflakes induced by SAMs with molecular dipole moments determined the charge transfer process. KFM results clearly demonstrated the charge transfer between MoS2 and SAMs and the obvious interlayer screening effect of the pristine and SAM-modified MoS2 nanoflakes. However, the KFM results were not fully consistent with the Raman and FET results since the externally absorbed water molecules were shown to partially shield the actual surface potential measurement. By eliminating the contribution of the water molecules, the Fermi level of monolayer MoS2 could be estimated to modulate in a range of more than 0.45–0.47 eV. This work manifests that the work function of MoS2 nanoflakes can be significantly tuned by SAMs by virtue of affecting the electrostatic potential between the substrates and MoS2 nanoflakes.Keywords: charge transfer; Kelvin probe microscopy; MoS2 nanoflakes; self-assembled monolayer; surface potential
Co-reporter:S. Ding, C.Y. Xu, W.S. Wang, Y.D. Huang, L. Zhen
Materials Research Bulletin 2013 48(11) pp: 4565-4569
Publication Date(Web):
DOI:10.1016/j.materresbull.2013.07.014
Co-reporter:Xiao-Liang Pan, Cheng-Yan Xu and Liang Zhen
CrystEngComm 2012 vol. 14(Issue 20) pp:6412-6418
Publication Date(Web):22 May 2012
DOI:10.1039/C2CE25593F
Olivine-structured LiMnPO4 microspheres assembled by plates, wedges and prisms with different crystallographic orientations were synthesized via a facile hydrothermal route at 200 °C for 10 h. Na2S·9H2O was employed as a sole additive for controlling the phase, shape and crystallographic orientation of LiMnPO4 microspheres. The obtained product was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The possible formation mechanism was proposed based on time-dependent experiments. The electrochemical properties of carbon-coated LiMnPO4 samples with different assembly units were investigated. The synthesized LiMnPO4 microspheres assembled with plates exhibited higher discharge capacity, more stable cycling stability and better rate capability, which were attributed to the exposed (010) facets as well as small thickness along the [010] direction allowing for a fast Li+ ion diffusion rate and short diffusion length.
Co-reporter:Cheng-Yan Xu, Jia Wu, Liang-Xing Lv, Jian-Xun Cui, Zeng-Quan Wang, Yu-Dong Huang and Liang Zhen
CrystEngComm 2011 vol. 13(Issue 7) pp:2674-2677
Publication Date(Web):14 Feb 2011
DOI:10.1039/C0CE00625D
We presented, for the first time, the evidence of loop-by-loop self-coiling of a nanobelt to form single-crystal Na2Ti6O13 nanorings with diameters of several micrometres. The winding nanobelts, with thickness of about 15 nm and widths of 100–500 nm, grow along their [010] crystallographic directions, and coherently match at ±(200) crystallographic planes. The driving force of such a coherent match is suggested to be the minimization of local electrostatic energy introduced by the cations and anions. We also discussed the dependence of the nanoring's yield on the thickness of the nanobelts, which affects the elastic deformation energy and misfit energy of the rings.
Co-reporter:J.N. An, C.Y. Xu, L. Zhen, Y.D. Huang
Ceramics International 2010 Volume 36(Issue 6) pp:1825-1829
Publication Date(Web):August 2010
DOI:10.1016/j.ceramint.2010.03.031
Abstract
Single-crystal K2V8O21 nanobelts were prepared from the reaction between V2O5 and KHSO4 under hydrothermal condition using no surfactant or template. The synthesized nanobelts were characterized by X-ray diffraction, X-ray photon-electron spectrometry, scanning electron microscopy, and transmission electron microscopy. The nanobelts are single-crystalline in nature, and have typical width of 100–500 nm, thickness of less than 100 nm and length up to a few tens of microns. The effects of solution concentration, reaction temperature and molar ratio of K and V on the morphology and phase component of the obtained products have been investigated. The possible formation mechanism was also discussed.
Co-reporter:Shuang Yang, Cheng-Yan Xu, Bao-You Zhang, Li Yang, Sheng-Peng Hu, Liang Zhen
Journal of Colloid and Interface Science (1 April 2017) Volume 491() pp:
Publication Date(Web):1 April 2017
DOI:10.1016/j.jcis.2016.12.028
Hierarchical structures assembled by two-dimensional (2D) nanosheets could inherit the characteristics of nanosheets and acquire additional advantages from the unique secondary architectures, which would have important influences on the photocatalytic properties of semiconductor nanomaterials. In this work, we successfully synthesized Ca(II) doped β-In2S3 hierarchical structures stacked by thin nanosheets by a simple solution chemical process. The effects of reaction temperature and Ca2+ concentration on the size and morphology of the products were systematically investigated. The photocatalytic applications of the β-In2S3 hierarchical structures were evaluated for hydrogen production and degradation of Rhodamine B (RhB) under visible light irradiation (λ > 420 nm). The β-In2S3 hierarchical structures showed promising activity towards photocatalytic hydrogen production (145.0 μmol g−1 h−1) and RhB solution (1 × 10−5 M) was completely degraded within 100 min under visible light irradiation.Ca(II) doped β-In2S3 hierarchical structures were synthesized through a facile hot-injection method. These β-In2S3 hierarchical structures exhibited enhanced hydrogen production and efficient degradation of organic dye under visible light irradiation.Download high-res image (107KB)Download full-size image
Co-reporter:Jing Yu, Qianqian Li, Cheng-Yan Xu, Na Chen, Yuan Li, Heguang Liu, Liang Zhen, Vinayak P. Dravid and Jinsong Wu
Journal of Materials Chemistry A 2017 - vol. 5(Issue 8) pp:NaN3986-3986
Publication Date(Web):2017/01/18
DOI:10.1039/C6TA10303K
The development of highly efficient water oxidation electrocatalysts made of low-cost and earth-abundant elements is a prerequisite. Sluggish kinetics in the reaction of water splitting is the major obstacle. Herein, we report the fabrication of a robust catalyst for the oxygen evolution reaction (OER) based on the hybrid of N-doped graphene coupled metallic NiSe2 pyramids (NG/NiSe2/NF). The reaction kinetics has greatly increased due to the synergistic effects of the two components providing enhanced electroconductibility and increased active sites. The NG/NiSe2/NF electrode exhibits superior water oxidation ability and cycle stability. This approach opens ways to design effective oxygen evolution electrodes.
Co-reporter:Wang-Da Li, Cheng-Yan Xu, Xiao-Liang Pan, Yu-Dong Huang and Liang Zhen
Journal of Materials Chemistry A 2013 - vol. 1(Issue 17) pp:NaN5369-5369
Publication Date(Web):2013/02/21
DOI:10.1039/C3TA01609A
LixV2O5 (x ∼ 0.42) nanorods, an overdoped β-phase vanadium oxide bronze with a rigid three-dimensional framework, have been fabricated for the first time via a simple two-step synthetic method. It is found that the δ-type structure of the as-prepared hydrated nanobelts through the hydrothermal route is converted into the tunnel β geometry upon annealing-induced dehydration. After annealing at 600 °C, the β-LixV2O5 nanorods exhibit the desired electrochemical properties: an initial gravimetric discharge capacity of 388.4 mA h g−1 (corresponding to an uptake of ca. 2.68 lithium per cell unit) and a specific energy density of 1039.6 W h kg−1 are achieved within a 2.0 V cut-off voltage at C/20, which decreased to 295.3 mA h g−1 (ca. 2.04 Li/V2O5) and 789.0 W h kg−1 after 50 cycles, respectively. The irreversible formation of ω-LixV2O5 for layered V2O5 cathodes upon deep lithiation is not presented during cell operation, and such improved structural reversibility is attributed to the highly retrievable host framework of the β-Li bronze, as well as further strain relaxation facilitated by the one-dimensional nanostructures. Based on the distinctive crystallographic structure and superior electrochemical properties, this β-lithium vanadium bronze has shown promising potential as a cathode material for secondary lithium-based batteries.
Co-reporter:Sheng-Peng Hu, Cheng-Yan Xu, Fei-Xiang Ma, Lei Cao and Liang Zhen
Dalton Transactions 2014 - vol. 43(Issue 22) pp:NaN8445-8445
Publication Date(Web):2014/03/24
DOI:10.1039/C3DT53561D
We report the solvothermal synthesis of hierarchical structures of orthorhombic Sb2WO6 and their implementation as a visible-light-driven photocatalyst for the degradation of Rhodamine B. The obtained hierarchical structures constructed by tiny nanosheets are doughnut-like flat ellipsoids with concaves in the centres, and with typical sizes of 1.3 μm in length, 800 nm in width and 400 nm in thickness. The concave characteristics and sizes of Sb2WO6 hierarchical structures can be tuned by adjusting the volume ratio of EG–H2O. Time-dependent experiments reveal that the formation process of concave structures involves the aggregation of nanoparticles to form solid spheres, dissolution–recrystallization to form hierarchical structures subsequently, and an Ostwald ripening process to shape the desired concaves finally. Under visible-light irradiation, complete degradation of Rhodamine B is achieved within 180 min in the presence of Sb2WO6 hierarchical structures, which could be ascribed to the porous structures, high BET surface area (42.58 m2 g−1) and wide absorption in the visible-light region.
Co-reporter:Fei-Xiang Ma, Pan-Pan Wang, Cheng-Yan Xu, Jing Yu, Hai-Tao Fang and Liang Zhen
Journal of Materials Chemistry A 2014 - vol. 2(Issue 45) pp:NaN19337-19337
Publication Date(Web):2014/09/30
DOI:10.1039/C4TA03008G
Self-stacked CuFe2O4–Fe2O3 porous nanosheets were prepared via a facile polyol-mediated route followed by calcination. Because of its highly porous structures and good electrical and ion conductivity of the well-dispersed CuFe2O4 phase in the matrix, the hybrid material exhibits high specific capacity of 910 mA h g−1 at 0.5 C after 200 cycles, superior capacity retention (0.02% capacity loss per cycle) and good rate capability (417 mA h g−1 at 4 C) as a promising anode material for Li-ion batteries.
