Co-reporter:Li Zhong, Kaibin Li, Yuanyuan Luo, Ming Li, Hua Wang, and Guanghai Li
Crystal Growth & Design November 1, 2017 Volume 17(Issue 11) pp:5927-5927
Publication Date(Web):October 11, 2017
DOI:10.1021/acs.cgd.7b01037
VO2 polymorphic nanoparticles (NPs) were synthesized by hydrothermal reaction in the presence of surfactant bis(2-ethylhexyl) sulfosuccinate sodium salt (AOT). The AOT acts as both growth inhibitor and soft template in the formation of VO2 polymorphs, and there is a definite phase evolution process with prolonging reaction time: (NH4)2V6O16·1.5H2O → NH4V4O10 → VO2(B) → VO2(B+D) → VO2(D) → VO2(D+P) → VO2(P). The formation mechanisms of the VO2(D) and VO2(P) phases were found to be, respectively, a dissolution–recrystallization and recrystallization process. The as-prepared VO2(P) can be easily transformed to VO2(M) NPs after a mild annealing treatment, and the VO2(M) composite films show an excellent infrared performances. The clarification of phase evolution of VO2 polymorphs during hydrothermal treatment can help in understanding the formation mechanism and selective synthesis of different VO2 metastable phases.
Co-reporter:C. J. Tang;G. H. Li;X. C. Dou;Y. X. Zhang;L. Li
The Journal of Physical Chemistry C April 9, 2009 Volume 113(Issue 14) pp:5422-5427
Publication Date(Web):2017-2-22
DOI:10.1021/jp810164s
The linear and volumetric thermal expansion coefficients of bismuth nanowire and nanoflower have been measured from 298 to 478 K by high-temperature X-ray diffraction methods. The bismuth nanowire and nanoflower were prepared by a simple solvothermal technique. It was found that the linear and volumetric thermal expansion coefficient of the nanowire decreases initially, then increases, and decreases finally with increasing temperature. The nanowire and nanoflower possess smaller linear thermal expansion coefficient in the a-axis direction in the whole measured temperature range and in the c-axis direction at high temperature as compared to the conventional bulk bismuth. The volumetric expansion coefficients of the nanowire and nanoflower are always smaller than those of the corresponding bulk materials. The results were discussed on the basis of the contributions from point defects, stress, and valence electrons. Our results demonstrated that the anisotropic thermal expansion behavior of bismuth nanowires is an intrinsic property.
Co-reporter:Y.Y. Luo, F.H. Su, C. Zhang, L. Zhong, S.S. Pan, S.C. Xu, H. Wang, J.M. Dai, G.H. Li
Optics Communications 2017 Volume 387() pp:385-389
Publication Date(Web):15 March 2017
DOI:10.1016/j.optcom.2016.10.061
•Adjust the THz optical conductivity of V2O3 by changing the external temperature.•The THz amplitude modulation can reach as high as 74.7%.•THz conductivity of metal-phase V2O3 can be well-fitted by the Drude-Smith model.•Revealed that the electron scattering processes depend on the temperature.The dynamic behavior of thermally-induced metal-insulator transition of V2O3 thin film on Si substrate grown by reactive magnetron sputtering was investigated by the terahertz time-domain spectroscopy. It was found that the THz absorption and optical conductivity of the thin films are temperature-dependent, and the THz amplitude modulation can reach as high as 74.7%. The complex THz optical conductivity in the metallic state of the V2O3 thin films can be well-fitted by the Drude-Smith model, which offer the insight into the electron transport dynamic during the metal-insulator transition of the thin film.
Co-reporter:Junqian Zhao, Huaina Yu, Shusheng Pan, Shang Zhou, Li Zhong, Hua Wang, Yuan Yuan Luo, SiuFung Yu, Guanghai Li
Journal of Luminescence 2017 Volume 188(Volume 188) pp:
Publication Date(Web):1 August 2017
DOI:10.1016/j.jlumin.2017.04.069
CsPbI3 sub-micrometer wires were synthesized by one-pot solution method at near room temperature. The wires are single crystalline with [100] orientation. An strong emission band centered at 470 nm was observed under ultraviolet excitation, and the emission intensity and bandwidth are dependent on the molar ratio of CsI/PbI2 in the wires. A bright green emission with a lifetime of several tens ns was observed when excited with a soft X-ray, and the spectral response range can be modulated by the molar ratio of CsI/PbI2 in the wires. The growth mechanism of the wires was discussed, and the influences of the cycling strain and X-ray irrigation time on the X-ray excited optical luminescence of the CsI/PbI2 wires/PET film were analyzed and discussed.
Co-reporter:Hao Wu;Hua Wang
Analyst (1876-Present) 2017 vol. 142(Issue 2) pp:326-335
Publication Date(Web):2017/01/16
DOI:10.1039/C6AN01959E
A general route to transform metal oxide semiconductors from non-SERS active to SERS-active substrates based on defect engineering is reported. The SERS enhancement factor (EF) of metal oxide semiconductors like α-MoO3 and V2O5 can be greatly enhanced and the SERS performance can be optimized according to the detecting analyte and activating laser wavelength by introducing oxygen vacancy defects. The EF of R6G on α-MoO3−x nanobelts can be as high as 1.8 × 107 with a detection limit of 10−8 M, which is the best among metal oxide semiconductors and comparable to noble metals without a “hot spot”. A model, named “effective electric current model”, was proposed to describe the photo-induced charge transfer process between the absorbed molecules and semiconductor substrates. The EF of 4-MBA, R6G and MB on α-MoO3−x nanobelts with different oxygen vacancy concentrations calculated based on the model matches very well with experimental results. As an extension, some potential metal oxide semiconductor SERS-active substrates were predicted based on the model. Our results clearly demonstrate that, through defect engineering, the metal oxide semiconductors can be made SERS-active substrates with high stability and high biocompatibility.
Co-reporter:Y.Y. Luo, S.S. Pan, S.C. Xu, L. Zhong, H. Wang, G.H. Li
Journal of Alloys and Compounds 2016 Volume 664() pp:626-631
Publication Date(Web):15 April 2016
DOI:10.1016/j.jallcom.2015.12.222
•Optimal conditions are achieved to grow pure VO2 (M) thin film.•Optical/electrical switching property of the VO2 film depend on sputtering power.•Film thickness and defect density affect amplitude of transition.•Grain size effect controls the hysteresis width of phase transition.The influence of sputtering power on the electrical and infrared properties of VO2 thin films was investigated. It was found that the controlling of sputtering power is very important in realizing the pure VO2 (M) thin film. The thin films grown at the sputtering powers of 350 W and above have a similar phase transition behavior to bulk VO2. The infrared transmittance and electrical resistance of the VO2 thin film also depend on the sputtering power, and the hysteresis width is controlled by the size effect. The film thickness and defect density affect the amplitudes of the phase transition and phase transition temperature.
Co-reporter:Y.Y. Luo, F.H. Su, S.S. Pan, S.C. Xu, C. Zhang, J. Pan, J.M. Dai, P. Li, G.H. Li
Journal of Alloys and Compounds 2016 Volume 655() pp:442-447
Publication Date(Web):15 January 2016
DOI:10.1016/j.jallcom.2015.08.254
•The maximum amplitude modulation reaches 75.9%.•The THz conductivity in metallic state of film can be fitted by the Drude-Smith model.•The metallic domain fractions across MIT can be extracted by EMT simulation.•The mechanisms of the THz transmission and conductivity were discussed.The terahertz (THz) conductivities in the metal-insulator transition process of VO2 thin films on quartz substrates were investigated by using terahertz time-domain spectroscopy. It was found that the THz absorption and conductivity of the thin films are sensitive to the sputtering gas pressure, and the maximum THz amplitude modulation can reach as high as 75.9%. The complex THz conductivity in metallic state of the thin films can be well-fitted by the Drude-Smith model, and the temperature-dependent metallic domain fractions can be extracted by effective medium theory simulation. Based on these results, the metal-insulator transition of the VO2 thin films can be characterized. The mechanisms of the THz transmission and conductivity were analyzed and discussed.
Co-reporter:S. C. Xu, H. L. Ding, S. S. Pan, Y. Y. Luo, and G. H. Li
ACS Sustainable Chemistry & Engineering 2016 Volume 4(Issue 12) pp:
Publication Date(Web):October 10, 2016
DOI:10.1021/acssuschemeng.6b01831
Rutile TiO2 nanograss was synthesized by a hydrothermal method on Ti mesh. The nanograss is composed of thin TiO2 nanorods with abundantly exposed {110} facets. The TiO2 nanograss on Ti mesh (TNTM) shows an excellent photocatalytic removal of Cr(VI) ions from plating wastewater under sunlight, and the removal capacity can reach as high as 143.8 mg/g. It was found that an external electric field can greatly enhance the removal efficiency of the TNTM, in which the electrons provided by the electric field can effectively neutralize the photoholes and inhibit the recombination of photoelectrons and photoholes. The TNTM can be easily removed after photocatalytic reaction and can be nondestructively regenerated by an electrolyzing process. The Cr(III) ions on the TNTM can be collected by the electrolyzation, effectively avoiding secondary pollution.Keywords: Cr(III) collection; Cr(VI) removal; Electric field enhancement; Nondestructive regeneration; TiO2;
Co-reporter:Hualin Ding;Yunxia Zhang;Sichao Xu
Nano Research 2016 Volume 9( Issue 12) pp:3632-3643
Publication Date(Web):2016 December
DOI:10.1007/s12274-016-1233-4
Yolk/shell nanoparticles (NPs), which integrate functional cores (likes Fe3O4) and an inert SiO2 shell, are very important for applications in fields such as biomedicine and catalysis. An acidic medium is an excellent etchant to achieve hollow SiO2 but harmful to most functional cores. Reported here is a method for preparing sub-100 nm yolk/shell Fe3O4@SiO2 NPs by a mild acidic etching strategy. Our results demonstrate that establishment of a dissolution–diffusion equilibrium of silica is essential for achieving yolk/shell Fe3O4@SiO2 NPs. A uniform increase in the silica compactness from the inside to the outside and an appropriate pH value of the etchant are the main factors controlling the thickness and cavity of the SiO2 shell. Under our “standard etching code”, the acid-sensitive Fe3O4 core can be perfectly preserved and the SiO2 shell can be selectively etched away. The mechanism of regulation of SiO2 etching and acidic etching was investigated.
Co-reporter:Dr. Jing Pan;Li Zhong;Dr. Ming Li;Dr. Yuanyuan Luo; Guanghai Li
Chemistry - A European Journal 2016 Volume 22( Issue 4) pp:1461-1466
Publication Date(Web):
DOI:10.1002/chem.201504259
Abstract
Monodispersed hierarchically structured V2O5 hollow spheres were successfully obtained from orthorhombic VO2 hollow spheres, which are in turn synthesized by a simple template-free microwave-assisted solvothermal method. The structural evolution of VO2 hollow spheres has been studied and explained by a chemically induced self-transformation process. The reaction time and water content in the reaction solution have a great influence on the morphology and phase structure of the resulting products in the solvothermal reaction. The diameter of the VO2 hollow spheres can be regulated simply by changing vanadium ion content in the reaction solution. The VO2 hollow spheres can be transformed into V2O5 hollow spheres with nearly no morphological change by annealing in air. The nanorods composed of V2O5 hollow spheres have an average length of about 70 nm and width of about 19 nm. When used as a cathode material for lithium-ion batteries, the V2O5 hollow spheres display a diameter-dependent electrochemical performance, and the 440 nm hollow spheres show the highest specific discharge capacity of 377.5 mAhg−1 at a current density of 50 mAg−1, and are better than the corresponding solid spheres and nanorod assemblies.
Co-reporter:Shusheng Pan, Xiaolin Liu, Min Guo, Siu fung Yu, Haitao Huang, Hongtao Fan and Guanghai Li
Journal of Materials Chemistry A 2015 vol. 3(Issue 21) pp:11437-11443
Publication Date(Web):05 May 2015
DOI:10.1039/C5TA00956A
Ti3+-doped amorphous TiO2 nanoparticles (a-TiO2:Ti3+), which are an intermediate band semiconductor, were fabricated by high intensity ultraviolet pulsed laser ablation in water. The absorption band of a-TiO2:Ti3+ nanoparticles, which appears between the visible and infrared regions, is much wider than that of the rutile TiO2 nanoparticles. The intermediate band, which has a recombination lifetime of 0.71 μs, is found to be 1.61 eV above the valence band (VB) top of TiO2. It can be shown that the a-TiO2:Ti3+/TiO2 nanotube hybrid dye-sensitized solar cells (DSSCs) not only have a high fill factor and large open circuit voltage, but also have high photovoltaic conversion efficiency as compared to TiO2 nanotube DSSCs. Considering that most of the current solar cells use only a single photoelectric conversion material (PCM), our results will promote the research on multi-PCM hybrid solar cells.
Co-reporter:Li Zhong, Ming Li, Hua Wang, Yuanyuan Luo, Jing Pan and Guanghai Li
CrystEngComm 2015 vol. 17(Issue 30) pp:5614-5619
Publication Date(Web):24 Jun 2015
DOI:10.1039/C5CE00873E
Star-shaped VO2 (M) nanoparticles were synthesized by hydrothermal reaction using only ammonium metavanadate and formic acid combined with subsequently mild annealing treatment. Enhanced thermochromic performance was demonstrated upon changing the temperature and the applied pulse voltage for the star-shaped VO2 (M) nanoparticle thin films.
Co-reporter:J. Pan, M. Li, Y.Y. Luo, H. Wu, L. Zhong, Q. Wang, G.H. Li
Applied Surface Science 2015 Volume 333() pp:34-38
Publication Date(Web):1 April 2015
DOI:10.1016/j.apsusc.2015.01.242
Highlights
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V2O5 nanoparticles (NPs) of different sizes have been synthesized.
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SERS activity of R6G over V2O5 NPs is size-dependent.
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42 nm V2O5 NPs have a detecting limit better than 10−8 M R6G.
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SERS activity of R6G over V2O5 NPs is wavelength-dependent.
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Energy matching between V2O5 and R6G is essential in PICT process.
Co-reporter:Shusheng Pan, Wei Lu, Zhaoqin Chu, Guanghai Li
Journal of Materials Science & Technology 2015 Volume 31(Issue 6) pp:670-673
Publication Date(Web):June 2015
DOI:10.1016/j.jmst.2014.09.017
Tin oxide (SnO2) is a promising wide bandgap semiconductor for next generation ultraviolet (UV) non-polar optoelectronic devices applications. The development of SnO2-based optoelectronic devices is obsessed by its low exciton emission efficiency. In this study, quantum confined SnO2 nanocrystals have been fabricated via pulsed laser ablation in water. The SnO2 quantum dots (QDs) possess high performance exciton emission at 297–300 nm light in water. The exciton emission intensity and wavelength can be slightly tuned by laser pulse energy and irradiation time. Optical gain has been observed in SnO2 QDs. Therefore, SnO2 QDs can be a promising luminescence material for the realization of deep UV nano-emitter and lasing devices.
Co-reporter:Ming Li, Xing Wu, Liang Li, Yuxi Wang, Dengbing Li, Jing Pan, Sijia Li, Litao Sun and Guanghai Li
Journal of Materials Chemistry A 2014 vol. 2(Issue 13) pp:4520-4523
Publication Date(Web):08 Jan 2014
DOI:10.1039/C3TA14822J
This paper reports the phase transition temperature regulation of VO2 (M) nanoparticles using interfacial defects and size effect other than the traditional doping routine. The nanoparticles exhibit excellent thermochromic performance and a low threshold voltage.
Co-reporter:Jianwei Su, Yunxia Zhang, Sichao Xu, Shuan Wang, Hualin Ding, Shusheng Pan, Guozhong Wang, Guanghai Li and Huijun Zhao
Nanoscale 2014 vol. 6(Issue 10) pp:5181-5192
Publication Date(Web):21 Feb 2014
DOI:10.1039/C4NR00534A
Herein, we demonstrate the design and fabrication of the well-defined triple-shelled Ag@Fe3O4@SiO2@TiO2 nanospheres with burr-shaped hierarchical structures, in which the multiple distinct functional components are integrated wonderfully into a single nanostructure. In comparison with commercial TiO2 (P25), pure TiO2 microspheres, Fe3O4@SiO2@TiO2 and annealed Ag@Fe3O4@SiO2@TiO2 nanocomposites, the as-obtained amorphous triple-shelled Ag@Fe3O4@SiO2@TiO2 hierarchical nanospheres exhibit a markedly enhanced visible light or sunlight photocatalytic activity towards the photodegradation of methylene blue and photoreduction of hexavalent chromium ions in wastewater. The outstanding photocatalytic activities of the plasmonic photocatalyst are mainly due to the enhanced light harvesting, reduced transport paths for both mass and charge transport, reduced recombination probability of photogenerated electrons/holes, near field electromagnetic enhancement and efficient scattering from the plasmonic nanostructure, increased surface-to-volume ratio and active sites in three dimensional (3D) hierarchical porous nanostructures, and improved photo/chemical stability. More importantly, the hierarchical nanostructured Ag@Fe3O4@SiO2@TiO2 photocatalysts could be easily collected and separated by applying an external magnetic field and reused at least five times without any appreciable reduction in photocatalytic efficiency. The enhanced photocatalytic activity and excellent chemical stability, in combination with the magnetic recyclability, make these multifunctional nanostructures promising candidates to remediate aquatic contaminants and meet the demands of future environmental issues.
Co-reporter:Ming Li, Shulin Ji, Jing Pan, Hao Wu, Li Zhong, Qiang Wang, Fadi Li and Guanghai Li
Journal of Materials Chemistry A 2014 vol. 2(Issue 48) pp:20470-20473
Publication Date(Web):20 Oct 2014
DOI:10.1039/C4TA04738A
An electrothermochromic VO2 nanoparticles film based on a Ag nanowires heater was prepared. The infrared performance of the film can be dynamically regulated and controlled by an applied voltage with high stability and reversibility. The film can overcome the high Tc limit of VO2 in practical applications and can be built on flexible substrates.
Co-reporter:Dengbing Li, Ming Li, Jing Pan, Yuanyuan Luo, Hao Wu, Yunxia Zhang, and Guanghai Li
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 9) pp:6555
Publication Date(Web):April 15, 2014
DOI:10.1021/am500135d
This paper reports a one-step TiO2 seed-assistant hydrothermal synthesis of Mo-doped VO2(M)/TiO2 composite nanocrystals. It was found that excess Mo doping can promote formation of the VO2(M) phase, and rutile TiO2 seed is beneficial to morphology control, size reduction, and infrared modulation of Mo-doped VO2(M) nanocrystals. The Mo-doped VO2 nanocrystals epitaxially grow on TiO2 seeds and have a quasi-spherical shape with size down to 20 nm and a nearly 35% infrared modulation near room temperature. The findings of this work demonstrate important progress in the near-room-temperature thermochromic performance of VO2(M) nanomaterials, which will find potential application in constructing VO2(M) nanocrystal-based smart window coatings.Keywords: hydrothermal; phase transition temperature; rutile TiO2 seed; thermochromic performance; VO2 nanocrystals;
Co-reporter:Yue Xu, Sichao Xu, Shuan Wang, Yunxia Zhang and Guanghai Li
Dalton Transactions 2014 vol. 43(Issue 2) pp:479-485
Publication Date(Web):20 Sep 2013
DOI:10.1039/C3DT52004H
Well-crystallized BiOCl nanoplates with exposed {001} facets were synthesized by a facile electrochemical anodic oxidation method. The thickness of the nanoplates decreases with increasing citric acid content in the electrolyte. The optical absorption edge of the BiOCl nanoplates shifts to a longer wavelength with citric acid. The BiOCl nanoplates obtained with citric acid show a high photocatalytic activity for degrading rhodamine B (RhB) as compared with that without citric acid. The photocatalytic activity of BiOCl nanoplates is higher in degrading RhB dyes than in degrading rhodamine 6G, methyl orange and methyl blue dyes. The superoxide radical and holes are the two major active species in photocatalytic degradation of RhB by BiOCl nanoplates. Citric acid can decrease the overlap in the layered structure of BiOCl and reduce the nanoplates thickness, leading to the increase in the exposure of {001} facets and the enhanced photocatalytic activity.
Co-reporter:Dr. Shuan Wang;Yong Ding;Dr. Sichao Xu; Yunxia Zhang; Guanghai Li; Linhua Hu; Songyuan Dai
Chemistry - A European Journal 2014 Volume 20( Issue 17) pp:4916-4920
Publication Date(Web):
DOI:10.1002/chem.201304963
Abstract
A facile route to synthesize amorphous TiO2 nanospheres by a controlled oxidation and hydrolysis process without any structure-directing agents or templates is presented. The size of the amorphous TiO2 nanospheres can be easily turned from 20 to 1500 nm by adjusting either the Ti species or ethanol content in the reaction solution. The phase structure of nanospheres can be controlled by hydrothermal treatment. The TiO2 nanospheres show excellent size-dependent light-scattering effects and can be structured into a light-harvesting layer for dye-sensitized solar cells with a quite high power conversion efficiency of 9.25 %.
Co-reporter:Ming Li ; Dengbing Li ; Jing Pan ; Hao Wu ; Li Zhong ; Qiang Wang
The Journal of Physical Chemistry C 2014 Volume 118(Issue 29) pp:16279-16283
Publication Date(Web):July 3, 2014
DOI:10.1021/jp504815w
As the most widely studied thermochromic material, monoclinic vanadium dioxide (VO2 (M)) shows promising applications in the energy-saving field. Solid-state transformation, especially fast annealing, plays an important role in the production of VO2 nanomaterials. On the other hand, the fast process makes it impossible to real-time monitor the phase transition in VO2. In this paper, a differential scanning calorimetry technique is proposed to in situ trigger and dynamically track the phase transition of VO2 nanoparticles, which gives a distinguished method to identify the underlying size-dependent and defect-mediated structure phase transition.
Co-reporter:Yanyan Liu, Yunxia Zhang, Hualin Ding, Sichao Xu, Ming Li, Fengyu Kong, Yuanyuan Luo and Guanghai Li
Journal of Materials Chemistry A 2013 vol. 1(Issue 10) pp:3362-3371
Publication Date(Web):10 Jan 2013
DOI:10.1039/C3TA00953J
Here, an oil-in-water emulsion method was used to assemble monodisperse noble metallic nanoparticles (NPs) in the oil phase into aggregates in the aqueous phase. The original size of the NPs is an essential factor in determining the final morphology: beyond the critical size, spherical aggregates with the original NPs can be formed; otherwise, complex aggregates with coarsing NPs come into being. The aggregation level of NPs and consequent properties of the as-constructed spherical assemblies can be optimized through tuning the evaporation rate of the organic solvent. The fabricated assemblies can serve as highly sensitive surface-enhanced Raman scattering (SERS) platforms for the detection of chemical or biological molecules, showing significantly high SERS activity toward rhodamine 6G (R6G) dye and 4-aminothiophenol (4-ATP) molecules. In addition, we further demonstrate the use of these highly sensitive SERS-active substrates to identify melamine at 1 × 10−7 M to insure food safety and biosecurity. Furthermore, the catalytic reduction of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) in the presence of excess NaBH4 was also investigated, in which the as-prepared silver assemblies exhibited excellent catalytic activities due to their special 3D architecture and large number of active catalytic sites.
Co-reporter:S. C. Xu, Y. X. Zhang, Y. Y. Luo, S. Wang, H. L. Ding, J. M. Xu and G. H. Li
Analyst 2013 vol. 138(Issue 16) pp:4519-4525
Publication Date(Web):13 May 2013
DOI:10.1039/C3AN00750B
The production of SERS-active substrates which are uniform, sensitive, reproducibile and durable still remains an important issue. Here, we report a strategy for the fabrication of a large-area Ag-decorated TiO2 nanograss SERS-active substrate by a simple solvothermal approach combined with Ag evaporation. The nanograss consists of dense rutile TiO2 nanorods of about 5 nm in diameter and the decorated Ag nanoparticles are an average of 8 nm in diameter. The Ag protrusions and gaps between them contribute to three dimensional SERS “hot spots” which can be modulated by simply controlling the Ag evaporating parameters. The Ag-decorated TiO2 substrate is highly efficient in detecting rhodamine 6G (R6G) and 4-aminothiophenol (4-ATP) molecules and has good homogeneity. An obvious red shift and even high enhancement of b2 vibration mode were observed in detecting 4-ATP due to the effective charge transfer from the Ag atoms to sulfur atoms. The Ag-decorated TiO2 substrate can be easily self-cleaned and reactivated by visible light irradiation without obvious degeneration of SERS signals. Our results demonstrate that the Ag-decorated TiO2 substrate with high and homogeneous SERS activity has potential feasibility as a sensitive SERS probe.
Co-reporter:Ming Li;Deng-Bing Li;Jing Pan;Jian-Chao Lin ;Guang-Hai Li
European Journal of Inorganic Chemistry 2013 Volume 2013( Issue 7) pp:1207-1212
Publication Date(Web):
DOI:10.1002/ejic.201201118
Abstract
This paper reports a facile and low-cost routine for the selective synthesis of vanadium oxides by hydrothermal treatment of V2O5 sol. Our experiments found a defined phase evolution sequence [V2O5 V3O7·H2O VO2 (B) VO2 (A) VO2 (M)] that is strongly dependent on the hydrothermal temperature, pressure, and reaction time. A mechanism for the formation of the vanadium oxides based on the oriented attachment (OA) growth model is proposed and discussed. The VO2 (A + M) phase and the pure VO2 (M) phase each show an abrupt change in infrared transmittance with temperature, which demonstrates their potential for applications in the field of energy conservation, and the modulation in the infrared properties of the VO2 (M) phase, thanks to its high purity, is far more prominent than that of the mixture phase VO2 (A + M).
Co-reporter:Sichao Xu;Yunxia Zhang;Shuan Wang;Junmin Xu;Hualin Ding
European Journal of Inorganic Chemistry 2013 Volume 2013( Issue 14) pp:2601-2607
Publication Date(Web):
DOI:10.1002/ejic.201201475
Abstract
Size and shape, in particular of the external surfaces, are very important factors in determining the photocatalytic activity of TiO2 nanostructures. Here, we demonstrate that the sea-urchin-like rutile superstructure with ultrathin nanorods and exposed {110} faces is an excellent photocatalyst in the removal of CrVI ions from plating wastewater. The superstructure consists of ultrathin rutile nanorods with a specific surface area of 224.4 m2 g–1; the nanorods have a diameter of several nanometers, and the exposed faces are predominantly {110} faces. This special morphology exhibits a structure-enhanced catalytic activity because it facilitates the transport of photoelectrons to the rutile nanorod {110} faces and prevents them recombining with holes. The rutile superstructure proved excellent at removing chromium from plating wastewater by photocatalytic reduction of CrVI to CrIII in sunlight, and at adsorption of the CrIII ions. The removal effectiveness is nearly 100 % at initial Cr concentrations below 53.7 ppm, and the removal capacity can reach about 1000 mg g–1 under irradiation by sunlight for 3 hours.
Co-reporter:H. L. Ding, Y. X. Zhang, S. Wang, J. M. Xu, S. C. Xu, and G. H. Li
Chemistry of Materials 2012 Volume 24(Issue 23) pp:4572
Publication Date(Web):October 31, 2012
DOI:10.1021/cm302828d
In this work, we present the coating regulations of Fe3O4 nanoparticles (NPs) by the reverse microemulsion method to obtain the Fe3O4@SiO2 core/shell NPs. The regulation produces the core/shell NPs with a single core and with different shell thicknesses, and it especially can be applied to different sizes Fe3O4 NPs and avoid the formation of core-free silica particles. Our results reveal that the silica coating parameters suitable for Fe3O4 NPs with certain size are not definitely applicable to that with other sizes, and the match of the number of Fe3O4 NPs with aqueous domain is essential. We found that the small aqueous domain is suitable to coat ultrathin silica shell, while the large aqueous domain is indispensable for coating thicker shells. To avoid the formation of core-free silica particles, the thick silica shell can be achieved by increasing the content of either TEOS through the equivalently fractionated drops or ammonia with a decreased one-off TEOS. The ligand exchange between the intermediate processes of the silica coating is evidenced. Our results provide not only a strategy for synthesizing uniform Fe3O4@SiO2 core/shell NPs with controlled shell thickness, but also a regulation that can be applied to preparation other core–shell NPs.Keywords: core/shell; Fe3O4 nanoparticles; shell thickness; single core; SiO2 coating regulations;
Co-reporter:Yunxia Zhang, Hualin Ding, Yanyan Liu, Shusheng Pan, Yuanyuan Luo and Guanghai Li
Journal of Materials Chemistry A 2012 vol. 22(Issue 21) pp:10779-10786
Publication Date(Web):23 Apr 2012
DOI:10.1039/C2JM16293H
A very simple protocol, which involves the chemical reduction of AgNO3 and Fe(NO3)3 with ethylene glycol as reducing agent, has been developed for synthesizing Ag@Fe3O4 core/shell nanostructures in which the silver nanoparticle core was covered by a thicker layer of the Fe3O4 nanoparticle shell. The obtained Ag@Fe3O4 core/shell nanostructures simultaneously possess both strong magnetic responsiveness and tunable plasmonic properties. The plasmonic properties of the composite nanospheres are profoundly influenced by the high dielectric constant of the outer Fe3O4 shell layer and could be conveniently modulated over a broad spectral range spanning from the ultraviolet to near-infrared (NIR) regions (789 nm) by simply altering the thickness of the Fe3O4 shell. The localized surface plasmon resonances of the core/shell nanocomposites red-shifted with increasing thickness of the Fe3O4 shell. The morphology transformation of the Ag/Fe3O4 nanocomposites from core/shell structures with a continuous dense coating to flower-like nanostructures also allows the tuning of their plasmonic properties to be blue-shifted (to 510 nm). Catalytic degradation of rhodamine 6G (R6G) experiments show that the Ag/Fe3O4 composite nanostructures exhibit high catalytic activity by sodium borohydride. Due to the efficient optical response through localized surface plasmon resonances, the catalytic performance from the silver core and external magnetic manipulation from the Fe3O4 shell, such multifunctional nanoparticles will provide an opportunity for simultaneous optical detection and catalytic reduction with the additional benefit of relatively facile recovery and regeneration.
Co-reporter:F. Y. Kong, M. Li, X. Y. Yao, J. M. Xu, A. D. Wang, Z. P. Liu and G. H. Li
CrystEngComm 2012 vol. 14(Issue 11) pp:3858-3861
Publication Date(Web):12 Mar 2012
DOI:10.1039/C2CE25199J
Monodispersed vanadium dioxide (VO2) hollow microspheres aggregated by elliptical nanorods were synthesized via a one-step template-free method. The inside-out Ostwald ripening mechanism is responsible for the formation of the hollow microspheres.
Co-reporter:Shuan Wang, Junmin Xu, Hualin Ding, Shusheng Pan, Yunxia Zhang and Guanghai Li
CrystEngComm 2012 vol. 14(Issue 22) pp:7672-7679
Publication Date(Web):26 Jun 2012
DOI:10.1039/C2CE25827G
Nitrogen doping is a promising method to enhance the visible light absorption and photo-catalytic activity of TiO2. A new method is reported for the synthesis of nitrogen self-doped rutile TiO2 nanorods, along with the formation study of V-shaped N-doped TiO2 nanorods, using TiN as a precursor and using a hydrothermal method. Our synthesis method gives a facile and easy way to control nitrogen doping in a TiO2 lattice. Two types of the V-shaped nanorods, with a (101) coherent boundary of either 114.4° or 134.9° inner angle, were observed. The N-doped TiO2 nanorods exhibit an enhanced visible light absorption and red-shift in band gap in comparison with pure rutile TiO2 nanopowders. The mechanisms of N doping and the formation of the V-shaped nanorods are analyzed and discussed. The oriented attachment and Ostwald ripening are considered responsible for the formation and growth of the straight and V-shaped N-doped TiO2 nanorods.
Co-reporter:J.M. Xu, S. Wang, H.L. Ding, S.S. Pan, Y.X. Zhang, G.H. Li
Materials Research Bulletin 2012 47(12) pp: 4457-4462
Publication Date(Web):
DOI:10.1016/j.materresbull.2012.09.046
Co-reporter:Yunxia Zhang, Sichao Xu, Yuanyuan Luo, Shusheng Pan, Hualin Ding and Guanghai Li
Journal of Materials Chemistry A 2011 vol. 21(Issue 11) pp:3664-3671
Publication Date(Web):31 Jan 2011
DOI:10.1039/C0JM03727C
Mesoporous carbon capsules encapsulated with Fe3O4 nanoparticles were prepared by the successive coating of a silica layer and a subsequent mesoporous silica/carbon layer on the surface of Fe3O4 nanoparticles followed by chemical etching with NaOH solution. TEM observations show that the as-obtained samples had a rattle-like structure: Fe3O4 nanoparticles were encapsulated in the interior of the mesoporous carbon capsules. The typical nitrogen adsorption/desorption results demonstrate that the specific surface area for the as-prepared samples is up to 1570 m2 g−1, and the total pore volume is about 3.02 cm3 g−1. The porous wall structure of the lateral carbon capsules provides the sufficient spaces that contribute to high adsorption capacities and faster adsorption rates of pollutants molecules in aqueous media. The nanocomposites are superparamagnetic at room temperature with a saturation magnetization of 5.5 emu g−1, which provides the prerequisite for the fast magnetic separation in wastewater treatment application. Water treatment experiments indicated that the as-prepared samples exhibited higher adsorption rates and more effective removal capacity of organic pollutants compared with commercial activated carbon (AC), and their maximum adsorption capabilities for methylene blue (MB), congo red (CR), and phenol reached 608.04, 1656.9 and 108.38 mg g−1, respectively. The multifunctional nanocomposites can be potentially used as absorbents for fast, convenient, and highly efficient removal of pollutants from the wastewater, which will play important roles in the purification or desalination of natural water and industrial effluents.
Co-reporter:Ming Li, Fengyu Kong, Liang Li, Yunxia Zhang, Li Chen, Weiwei Yan and Guanghai Li
Dalton Transactions 2011 vol. 40(Issue 41) pp:10961-10965
Publication Date(Web):14 Sep 2011
DOI:10.1039/C1DT10941C
High quality single crystalline metastable phase VO2 (A) ultra-long nanobelts were synthesized by hydrothermal method using inorganic V2O5 sol as precursor and polyethylene glycol (PEG) as both surfactant and reducing agent. It was found that the oriented attach growth mechanism is responsible for the formation of VO2 (A) nanobelts. In addition to an endothermic peak, an unusual exothermic peak was detected in DSC curve of the nanobelts. The temperature dependence of the lattice parameters have been studied, and it was found that the a-axis expands while the c-axis contracts in the high-temperature XRD test. The VO2 (A) nanobelt has a low turn-on field of 3.8 V μm−1 and a high field enhancement factor of 1739 in the field emission measurement. Electrical transport measurement of a single VO2 (A) nanobelt gives a relative low hoping activation energy of 0.28 eV.
Co-reporter:Ming Li, Fengyu Kong, Hongqiang Wang and Guanghai Li
CrystEngComm 2011 vol. 13(Issue 17) pp:5317-5320
Publication Date(Web):19 Jul 2011
DOI:10.1039/C1CE05477E
A cost-saving and easy-handling sol-gel process coupled with a hydrothermal approach was proposed to synthesize V2O5 ultralong nanobelts by merely using inorganic V2O5 sol as the precursor without any organic or inorganic templates. An Oriented Attachment growth mechanism was suggested to explain the growth process of V2O5 ultralong nanobelts.
Co-reporter:Ming Li, Fengyu Kong, Yunxia Zhang and Guanghai Li
CrystEngComm 2011 vol. 13(Issue 7) pp:2204-2207
Publication Date(Web):15 Feb 2011
DOI:10.1039/C0CE00946F
Metastable phase VO2 (B) nanorings were synthesized by hydrothermal treatment of inorganic V2O5 sol. It was found that oriented attachment growth and a subsequent rolling mechanism are essential for the formation of VO2 (B) nanorings under hydrothermal conditions.
Co-reporter:F.Y. Kong, M. Li, S.S. Pan, Y.X. Zhang, G.H. Li
Materials Research Bulletin 2011 46(11) pp: 2100-2104
Publication Date(Web):
DOI:10.1016/j.materresbull.2011.06.030
Co-reporter:XC Dou;GH Li;XH Huang;L Li
Nanoscale Research Letters 2010 Volume 5( Issue 7) pp:
Publication Date(Web):2010 July
DOI:10.1007/s11671-010-9611-4
The lattice parameter of Bi/BiSb superlattice nanowire (SLNW) has been measured using in situ high-temperature X-ray diffraction method. The single crystalline Bi/BiSb SLNW arrays with different bilayer thicknesses have been fabricated within the porous anodic alumina membranes (AAMs) by a charge-controlled pulse electrodeposition. Different temperature dependences of the lattice parameter and thermal expansion coefficient were found for the SLNWs. It was found that the thermal expansion coefficient of the SLNWs with a large bilayer thickness has weak temperature dependence, and the interface stress and defect are the main factors responsible for the thermal contraction of the SLNWs.
Co-reporter:XH Huang;GH Li;GZ Sun;XC Dou;L Li;LX Zheng
Nanoscale Research Letters 2010 Volume 5( Issue 6) pp:
Publication Date(Web):2010 June
DOI:10.1007/s11671-010-9602-5
The initial growth stage of the single-crystalline Sb and Co nanowires with preferential orientation was studied, which were synthesized in porous anodic alumina membranes by the pulsed electrodeposition technique. It was revealed that the initial growth of the nanowires is a three-dimensional nucleation process, and then gradually transforms to two-dimensional growth via progressive nucleation mechanism, which resulting in a structure transition from polycrystalline to single crystalline. The competition among the nuclei inside the nanoscaled-confined channel and the growth kinetics is responsible for the structure transition of the initial grown nanowires.
Co-reporter:Hongqiang Wang, Guanghai Li, Lichao Jia, Liang Li and Guozhong Wang
Chemical Communications 2009 (Issue 25) pp:3786-3788
Publication Date(Web):19 May 2009
DOI:10.1039/B906787F
A high-temperature anisotropic silicon-etching strategy is demonstrated to steer the growth of the horizontally localized parallel Zn2SiO4nanowires.
Co-reporter:Xiaohu Huang, Guanghai Li, Lei Duan, Liang Li, Xincun Dou, Lide Zhang
Scripta Materialia 2009 Volume 60(Issue 11) pp:984-987
Publication Date(Web):June 2009
DOI:10.1016/j.scriptamat.2009.02.038
Single-crystalline (Mn, Ni)-co-doped ZnO nanosheets were in situ synthesized by a pulsed electrodeposition-assisted chemical bath deposition technique. In addition to structure and composition characterizations, detailed X-ray photoelectron spectroscopic analysis revealed that the magnetic dopants had been doped into the ZnO matrix. The nanosheets exhibited tunable room-temperature ferromagnetism. As well as spintronics, this kind of co-doped ZnO nanosheet could find interesting applications due to their large specific surface area and high population of polar faces.
Co-reporter:Xiaohu Huang, Guanghai Li, Bingqiang Cao, Ming Wang and Changyi Hao
The Journal of Physical Chemistry C 2009 Volume 113(Issue 11) pp:4381-4385
Publication Date(Web):2017-2-22
DOI:10.1021/jp810790h
Ni-doped ZnO nanostructures were synthesized in situ through a pulsed-electrodeposition-assisted chemical bath deposition method, and the optical and magnetic properties of the nanostructures were studied. It was found that the morphology of the nanostructures evolved from a rodlike to a sheetlike structure because of the different growth modes, and a growth mechanism is proposed to explain these findings. A relatively strong UV emission was observed for the nanorods, whereas a relatively strong visible emission was seen for the nanosheets. Ni was successfully doped into the ZnO wurtzite lattice structure as revealed by X-ray diffraction and X-ray photoelectron spectroscopy and also verified by the cathodoluminescence characterization. Room-temperature ferromagnetism was also observed in the Ni-doped ZnO nanostrucures. The results are helpful to tailor the physical properties of ZnO by changing its morphology and composition.
Co-reporter:Xincun Dou, Guanghai Li and Hechang Lei
Nano Letters 2008 Volume 8(Issue 5) pp:1286-1290
Publication Date(Web):March 26, 2008
DOI:10.1021/nl073039b
The growth mechanism of the electrodeposited single crystalline nanowires is generally considered to follow a three-dimensional to two-dimensional (2D) transition mode, and as for the 2D growth, it is ordinarily considered as a plane growth mode (layer-by-layer growth mechanism). We report in this Letter the growth of Bi/BiSb superlattice nanowires by adopting a charge-controlled pulse electrodeposition technique, and to our best knowledge, different growth modes of the nanowires, the 2D plane growth mode, the tilted plane growth mode, and the curved plane growth mode, were first observed. These growth modes were gathered and analyzed from the perspectives of crystal growth as well as kinetics and thermodynamics. It is shown that the superlattice nanowires are good structures for studying the growth mechanism of electrodeposited nanowires. This work will deeply benefit the understanding of the growth process of the electrodeposited nanowires and provide important experiment data to crystal growth theory.
Co-reporter:C.J. Tang, G.Z. Wang, H.Q. Wang, Y.X. Zhang, G.H. Li
Materials Letters 2008 Volume 62(21–22) pp:3663-3665
Publication Date(Web):15 August 2008
DOI:10.1016/j.matlet.2008.04.021
Bi2S3 nanowire arrays were synthesized via a facile hydrothermal method. X-ray diffraction, field emission scanning electron microscopy and transmission electron microscope were used to characterize the nanowire arrays. The nanowires are single crystalline with diameters in the range of 30 to 40 nm. The factors that affect the morphologies of the Bi2S3 nanowire arrays were studied, and it was found that the reaction time plays a key role in the morphology evolution of the nanowire arrays and thiourea is the optimum sulfur source for the growth of Bi2S3 nanowires. Crystalline redissolve recrystalline growth mechanism is proposed for the formation of nanowire arrays.
Co-reporter:Hongqiang Wang ; Guanghai Li ; Lichao Jia ; Guozhong Wang ;Chunjuan Tang
The Journal of Physical Chemistry C 2008 Volume 112(Issue 31) pp:11738-11743
Publication Date(Web):July 16, 2008
DOI:10.1021/jp803059k
Porous ZnO nanotubes have been synthesized via a facile hydrothermal method based on a preferential etching strategy. The nanotubes have a nearly homogeneous size with about 250 nm diameter, 40 nm wall thickness, and 500 nm length. Nanoholes with diameters ranging from tens to hundreds of nanometers were created on the side wall of the tubular structure. Formation of the porous ZnO nanotubes resulted from preferential etching along the c axis and relatively slow etching along the radial directions due to the polar feature of the ZnO crystal. Superior photocatalytic activity of the porous ZnO nanotubes in the degradation of methyl orange compared to the other samples has been demonstrated, and the origin is mainly ascribed to the scattered nanoholes on the wall of the porous nanotubes. The influence factors and formation mechanism of the porous ZnO nanotubes were analyzed and discussed.
Co-reporter:Xincun Dou ; Guanghai Li ; Xiaohu Huang ;Liang Li
The Journal of Physical Chemistry C 2008 Volume 112(Issue 22) pp:8167-8171
Publication Date(Web):May 3, 2008
DOI:10.1021/jp8004986
BiSb alloy nanotube−nanowire array has been fabricated by the pulsed electrodeposition technique. It was found that the growth of the polycrystalline nanotubes is terminated by polycrystalline nanowires abruptly and then follows by single crystalline nanowires. The formation mechanism of the nanotubes and the origin of the transition from a polycrystalline nanotube to a polycrystalline nanowire were analyzed and discussed from the perspective of the crystal growth theory. The deep understanding of the transition is of high importance for the controlled synthesis and application in thermoelectric field of Bi-based nanotubes arrays.
Co-reporter:Yunxia Zhang, Shusheng Pan, Xuemei Teng, Yuanyuan Luo and Guanghai Li
The Journal of Physical Chemistry C 2008 112(26) pp: 9623-9626
Publication Date(Web):June 5, 2008
DOI:10.1021/jp8015326
Bifunctional magnetic−luminescent Fe3O4@SiO2/Y2O3:Tb nanocomposite was obtained by assembling Y2O3:Tb nanorods onto the surface of Fe3O4@SiO2 core−shell nanostructures. Transmission electron microscopy, energy dispersive X-rays (EDX), room temperature photoluminescence spectra, and superconducting quantum interference device magnetometry were used to investigate the morphology and properties of the nanocomposite. The results showed that the nanocomposite displayed a strong green emission and superparamagnetic behavior at room temperature; therefore, the nanocomposite is expected to find many potential applications in biomedical fields.
Co-reporter:Xuemei Teng, Hongtao Fan, Shusheng Pan, Cong Ye, Guanghai Li
Materials Letters 2007 Volume 61(Issue 1) pp:201-204
Publication Date(Web):January 2007
DOI:10.1016/j.matlet.2006.04.031
The photoluminescence (PL) properties of ZnO thin films on ITO glass substrate deposited by rf magnetron sputtering with different oxygen partial pressures were studied. It was found that the exciton related emission of ZnO thin films depends on oxygen partial pressure, and that the visible emission related to intrinsic defects has no obvious change with various oxygen partial pressures. Abnormal UV-PL characteristics were observed, and its intensity was obviously enhanced. The emission position has a strong red-shift with increasing excitation intensity, and the emission intensity increases notably with increasing excitation cycle.
Co-reporter:Yuanyuan Luo, Guotao Duan, Guanghai Li
Journal of Solid State Chemistry 2007 Volume 180(Issue 7) pp:2149-2153
Publication Date(Web):July 2007
DOI:10.1016/j.jssc.2007.05.025
Flower-like Ni(OH)2 nanoarchitectures have been synthesized through a one-step mild hydrothermal reaction with the aid of ethylenediamine in NiCl2 aqueous solution. The flower with the size of several micrometers in diameter is composed of the ultra-thin nanosheets of several nanometers in thickness. It was found the ethylenediamine is vital to the formation of the flower-like nanoarchitectures. The influence of the concentration of the ethylenediamine and the reaction temperature on the formation of the flowers was analyzed and the formation mechanism of the flowers was proposed. Such flower-like β-Ni(OH)2 nanoarchitectures will find potential applications in the fields, such as electrode, or will be used as a starting material to produce NiO, which is widely used in the magnetic, catalysts, sensor and electrochromic devices.Flower-like Ni(OH)2 nanoarchitectures were synthesized by a one-step mild hydrothermal reaction with the aid of ethylenediamine in NiCl2 aqueous solution. The flower with the size of several micrometers in diameter is composed of the ultra-thin nanosheets of several nanometers in thickness. The flowers could be in catalysts, sensor and electrochromic devices, and alkaline rechargeable batteries.
Co-reporter:H.T. Fan, S.S. Pan, X.M. Teng, C. Ye, G.H. Li, L.D. Zhang
Thin Solid Films 2006 Volume 513(1–2) pp:142-147
Publication Date(Web):14 August 2006
DOI:10.1016/j.tsf.2006.01.074
Nanocrystalline δ-Bi2O3 thin films have been successfully prepared by radiofrequency reactive magnetron sputtering on Si(100) substrate using pure Bi as target. The influences of the oxygen flow ratio in the working gas and substrate temperature on the structures and phase components of the thin films were studied. The X-ray diffraction and transmission electron microscope analyses confirmed that the δ-Bi2O3 thin films with high quality are obtained at substrate temperature of about 200 °C and oxygen flow ratio between 5% and 10%. The absorption edge of the films has a strong blue shift with increasing the O2 flow ratio due to the quantum confinement effect and it was considered that the indirect allowed transition dominates in the δ-Bi2O3 thin films. The nanocrystalline nature of the δ-Bi2O3 thin films is responsible for the stabilization of high temperature phase in ambient temperature.
Co-reporter:C.J. Tang, Y.X. Zhang, X.C. Dou, G.H. Li
Journal of Crystal Growth (15 February 2010) Volume 312(Issue 5) pp:692-697
Publication Date(Web):15 February 2010
DOI:10.1016/j.jcrysgro.2009.12.025
Three-dimensional Bi2S3 matlike architectures have been synthesized via a seed-assistant hydrothermal synthesis method. The preformed Bi2S3 seed-layer on the substrate is crucial for the formation of the matlike architecture. The formation of the Bi2S3 fabric structure is via the splitting crystal growth mechanism of the preformed Bi2S3 nanosheets instead of through a topotactic transformation process of intermediate compound. The phase structures and morphologies of the Bi2S3 products were characterized by XRD, FESEM, and TEM. The formation process for Bi2S3 matlike architecture is investigated and discussed.
Co-reporter:S.C. Xu, S.S. Pan, Y. Xu, Y.Y. Luo, Y.X. Zhang, G.H. Li
Journal of Hazardous Materials (11 February 2015) Volume 283() pp:7-13
Publication Date(Web):11 February 2015
DOI:10.1016/j.jhazmat.2014.08.071
•Fe(II)/TiO2 spherical shell catalyst was synthesized by hydrothermal method.•Cr(VI) removal effectiveness reaches to 99.99% with 102.3 ppm initial content.•TiO2, Fe(II) and Fe0 atom synergistically contribute to Cr(VI) reduction.•Bulk Fe(II) doping enhance electron transference between TiO2 and Fe(II) ions.•Special spherical shell structure enhances the utilization of sunlight.Fe(II)-doped TiO2 spherical shell catalyst was synthesized by one-pot hydrothermal method. The photocatalytic removal of Cr(VI) from plating wastewater under sunlight of the catalyst was demonstrated. It was found that the removal effectiveness of about 99.99% for initial Cr(VI) concentration of 102.3 ppm and 99.01% for 153.4 ppm under 3 h sunlight irradiation is realized. The Fe(II) ions serve not only as reducing agents for reducing the Cr(VI) to Cr(III) but also as an intermedium of a two-step reduction, in which the TiO2 photoreduces the Fe(II) ions to Fe atoms firstly, and then the Fe atoms reduce the Cr(VI) to Cr(III). The improved photocatalytic activity of the catalyst is considered due to the synergistic effect of a multi reducing process by Fe(II) doping. The extended optical response and effectively utilization of sunlight of the special spherical-shell-like morphology also contribute to the enhanced photocatalytic activity.Download full-size image
Co-reporter:Ming Li, Hao Wu, Li Zhong, Hua Wang, Yuanyuan Luo and Guanghai Li
Journal of Materials Chemistry A 2016 - vol. 4(Issue 8) pp:NaN1583-1583
Publication Date(Web):2016/01/20
DOI:10.1039/C5TC04046A
An active and dynamic infrared switching film device was built via integrating VO2 (M) nanoparticles and the ITO glass substrate. The infrared optical transmittance of the device can be real-time manipulated by an applied voltage, overcoming the high Tc limit of VO2 (M) and providing a new insight into the applications of transparent conductive electrodes in the thermochromic field.
Co-reporter:Ming Li, Shulin Ji, Jing Pan, Hao Wu, Li Zhong, Qiang Wang, Fadi Li and Guanghai Li
Journal of Materials Chemistry A 2014 - vol. 2(Issue 48) pp:NaN20473-20473
Publication Date(Web):2014/10/20
DOI:10.1039/C4TA04738A
An electrothermochromic VO2 nanoparticles film based on a Ag nanowires heater was prepared. The infrared performance of the film can be dynamically regulated and controlled by an applied voltage with high stability and reversibility. The film can overcome the high Tc limit of VO2 in practical applications and can be built on flexible substrates.
Co-reporter:Yanyan Liu, Yunxia Zhang, Hualin Ding, Sichao Xu, Ming Li, Fengyu Kong, Yuanyuan Luo and Guanghai Li
Journal of Materials Chemistry A 2013 - vol. 1(Issue 10) pp:NaN3371-3371
Publication Date(Web):2013/01/10
DOI:10.1039/C3TA00953J
Here, an oil-in-water emulsion method was used to assemble monodisperse noble metallic nanoparticles (NPs) in the oil phase into aggregates in the aqueous phase. The original size of the NPs is an essential factor in determining the final morphology: beyond the critical size, spherical aggregates with the original NPs can be formed; otherwise, complex aggregates with coarsing NPs come into being. The aggregation level of NPs and consequent properties of the as-constructed spherical assemblies can be optimized through tuning the evaporation rate of the organic solvent. The fabricated assemblies can serve as highly sensitive surface-enhanced Raman scattering (SERS) platforms for the detection of chemical or biological molecules, showing significantly high SERS activity toward rhodamine 6G (R6G) dye and 4-aminothiophenol (4-ATP) molecules. In addition, we further demonstrate the use of these highly sensitive SERS-active substrates to identify melamine at 1 × 10−7 M to insure food safety and biosecurity. Furthermore, the catalytic reduction of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) in the presence of excess NaBH4 was also investigated, in which the as-prepared silver assemblies exhibited excellent catalytic activities due to their special 3D architecture and large number of active catalytic sites.
Co-reporter:Ming Li, Xing Wu, Liang Li, Yuxi Wang, Dengbing Li, Jing Pan, Sijia Li, Litao Sun and Guanghai Li
Journal of Materials Chemistry A 2014 - vol. 2(Issue 13) pp:NaN4523-4523
Publication Date(Web):2014/01/08
DOI:10.1039/C3TA14822J
This paper reports the phase transition temperature regulation of VO2 (M) nanoparticles using interfacial defects and size effect other than the traditional doping routine. The nanoparticles exhibit excellent thermochromic performance and a low threshold voltage.
Co-reporter:Shusheng Pan, Xiaolin Liu, Min Guo, Siu fung Yu, Haitao Huang, Hongtao Fan and Guanghai Li
Journal of Materials Chemistry A 2015 - vol. 3(Issue 21) pp:NaN11443-11443
Publication Date(Web):2015/05/05
DOI:10.1039/C5TA00956A
Ti3+-doped amorphous TiO2 nanoparticles (a-TiO2:Ti3+), which are an intermediate band semiconductor, were fabricated by high intensity ultraviolet pulsed laser ablation in water. The absorption band of a-TiO2:Ti3+ nanoparticles, which appears between the visible and infrared regions, is much wider than that of the rutile TiO2 nanoparticles. The intermediate band, which has a recombination lifetime of 0.71 μs, is found to be 1.61 eV above the valence band (VB) top of TiO2. It can be shown that the a-TiO2:Ti3+/TiO2 nanotube hybrid dye-sensitized solar cells (DSSCs) not only have a high fill factor and large open circuit voltage, but also have high photovoltaic conversion efficiency as compared to TiO2 nanotube DSSCs. Considering that most of the current solar cells use only a single photoelectric conversion material (PCM), our results will promote the research on multi-PCM hybrid solar cells.
Co-reporter:Ming Li, Fengyu Kong, Liang Li, Yunxia Zhang, Li Chen, Weiwei Yan and Guanghai Li
Dalton Transactions 2011 - vol. 40(Issue 41) pp:NaN10965-10965
Publication Date(Web):2011/09/14
DOI:10.1039/C1DT10941C
High quality single crystalline metastable phase VO2 (A) ultra-long nanobelts were synthesized by hydrothermal method using inorganic V2O5 sol as precursor and polyethylene glycol (PEG) as both surfactant and reducing agent. It was found that the oriented attach growth mechanism is responsible for the formation of VO2 (A) nanobelts. In addition to an endothermic peak, an unusual exothermic peak was detected in DSC curve of the nanobelts. The temperature dependence of the lattice parameters have been studied, and it was found that the a-axis expands while the c-axis contracts in the high-temperature XRD test. The VO2 (A) nanobelt has a low turn-on field of 3.8 V μm−1 and a high field enhancement factor of 1739 in the field emission measurement. Electrical transport measurement of a single VO2 (A) nanobelt gives a relative low hoping activation energy of 0.28 eV.
Co-reporter:Yue Xu, Sichao Xu, Shuan Wang, Yunxia Zhang and Guanghai Li
Dalton Transactions 2014 - vol. 43(Issue 2) pp:NaN485-485
Publication Date(Web):2013/09/20
DOI:10.1039/C3DT52004H
Well-crystallized BiOCl nanoplates with exposed {001} facets were synthesized by a facile electrochemical anodic oxidation method. The thickness of the nanoplates decreases with increasing citric acid content in the electrolyte. The optical absorption edge of the BiOCl nanoplates shifts to a longer wavelength with citric acid. The BiOCl nanoplates obtained with citric acid show a high photocatalytic activity for degrading rhodamine B (RhB) as compared with that without citric acid. The photocatalytic activity of BiOCl nanoplates is higher in degrading RhB dyes than in degrading rhodamine 6G, methyl orange and methyl blue dyes. The superoxide radical and holes are the two major active species in photocatalytic degradation of RhB by BiOCl nanoplates. Citric acid can decrease the overlap in the layered structure of BiOCl and reduce the nanoplates thickness, leading to the increase in the exposure of {001} facets and the enhanced photocatalytic activity.
Co-reporter:Hongqiang Wang, Guanghai Li, Lichao Jia, Liang Li and Guozhong Wang
Chemical Communications 2009(Issue 25) pp:NaN3788-3788
Publication Date(Web):2009/05/19
DOI:10.1039/B906787F
A high-temperature anisotropic silicon-etching strategy is demonstrated to steer the growth of the horizontally localized parallel Zn2SiO4nanowires.
Co-reporter:Yunxia Zhang, Sichao Xu, Yuanyuan Luo, Shusheng Pan, Hualin Ding and Guanghai Li
Journal of Materials Chemistry A 2011 - vol. 21(Issue 11) pp:NaN3671-3671
Publication Date(Web):2011/01/31
DOI:10.1039/C0JM03727C
Mesoporous carbon capsules encapsulated with Fe3O4 nanoparticles were prepared by the successive coating of a silica layer and a subsequent mesoporous silica/carbon layer on the surface of Fe3O4 nanoparticles followed by chemical etching with NaOH solution. TEM observations show that the as-obtained samples had a rattle-like structure: Fe3O4 nanoparticles were encapsulated in the interior of the mesoporous carbon capsules. The typical nitrogen adsorption/desorption results demonstrate that the specific surface area for the as-prepared samples is up to 1570 m2 g−1, and the total pore volume is about 3.02 cm3 g−1. The porous wall structure of the lateral carbon capsules provides the sufficient spaces that contribute to high adsorption capacities and faster adsorption rates of pollutants molecules in aqueous media. The nanocomposites are superparamagnetic at room temperature with a saturation magnetization of 5.5 emu g−1, which provides the prerequisite for the fast magnetic separation in wastewater treatment application. Water treatment experiments indicated that the as-prepared samples exhibited higher adsorption rates and more effective removal capacity of organic pollutants compared with commercial activated carbon (AC), and their maximum adsorption capabilities for methylene blue (MB), congo red (CR), and phenol reached 608.04, 1656.9 and 108.38 mg g−1, respectively. The multifunctional nanocomposites can be potentially used as absorbents for fast, convenient, and highly efficient removal of pollutants from the wastewater, which will play important roles in the purification or desalination of natural water and industrial effluents.
Co-reporter:Yunxia Zhang, Hualin Ding, Yanyan Liu, Shusheng Pan, Yuanyuan Luo and Guanghai Li
Journal of Materials Chemistry A 2012 - vol. 22(Issue 21) pp:NaN10786-10786
Publication Date(Web):2012/04/23
DOI:10.1039/C2JM16293H
A very simple protocol, which involves the chemical reduction of AgNO3 and Fe(NO3)3 with ethylene glycol as reducing agent, has been developed for synthesizing Ag@Fe3O4 core/shell nanostructures in which the silver nanoparticle core was covered by a thicker layer of the Fe3O4 nanoparticle shell. The obtained Ag@Fe3O4 core/shell nanostructures simultaneously possess both strong magnetic responsiveness and tunable plasmonic properties. The plasmonic properties of the composite nanospheres are profoundly influenced by the high dielectric constant of the outer Fe3O4 shell layer and could be conveniently modulated over a broad spectral range spanning from the ultraviolet to near-infrared (NIR) regions (789 nm) by simply altering the thickness of the Fe3O4 shell. The localized surface plasmon resonances of the core/shell nanocomposites red-shifted with increasing thickness of the Fe3O4 shell. The morphology transformation of the Ag/Fe3O4 nanocomposites from core/shell structures with a continuous dense coating to flower-like nanostructures also allows the tuning of their plasmonic properties to be blue-shifted (to 510 nm). Catalytic degradation of rhodamine 6G (R6G) experiments show that the Ag/Fe3O4 composite nanostructures exhibit high catalytic activity by sodium borohydride. Due to the efficient optical response through localized surface plasmon resonances, the catalytic performance from the silver core and external magnetic manipulation from the Fe3O4 shell, such multifunctional nanoparticles will provide an opportunity for simultaneous optical detection and catalytic reduction with the additional benefit of relatively facile recovery and regeneration.
