Xinzhen Wang

Hierarchical assembly of In2O3 nanoparticles on ZnO hollow nanotubes using carbon fibers as templates: Enhanced photocatalytic and gas-sensing properties

A novel hollow hierarchical nano-heterostructure consisting of ZnO nanorods coated with In2O3 nanoparticles was prepared using a hydrothermal method combined with an annealing treatment via carbon fiber (CF) templates. Experimental results reveal that the In2O3/ZnO hierarchical composite has a tubular structure with an average diameter of ∼6μm and In2O3 nanoparticles distribute uniformly on the ZnO nanorods. Significantly, the obtained heterostructure shows enhanced visible light photoactivity to methyl orange (MO) degradation and good selectivity and response toward ethanol even at a low detection limit (1ppm). This outstanding performance is a result of the one-dimensional tubular structure and the heterostructure formation between In2O3 and ZnO, advantageous for the adsorption and diffusion and the separation of electrons and holes. In addition, the excellent performance is greatly improved by virtue of the evenly decorated In2O3 nanoparticles on the ZnO nanorod surfaces, which provide more active sites for pollutants and gases.

Visible photocatalytic and photoelectrochemical activities of TiO2 nanobelts modified by In2O3 nanoparticles

Novel In2O3 nanoparticle/TiO2 nanobelt heterostructures with enhanced visible-light photocatalytic and photoelectrochemical (PEC) performance were successfully prepared via a facile hydrothermal method. Well-dispersed In2O3 nanoparticles with small sizes are uniformly attached on the surface of TiO2 nanobelts to form In2O3 nanoparticle/TiO2 nanobelt heterostructures. The TiO2 nanobelts as backbones restrict the aggregation of In2O3 nanoparticles, resulting in the formation of smaller In2O3 nanoparticles with more interaction sites for pollutants. The visible photocatalytic activity of as-prepared heterostructures for degradation of methyl blue (MB) is higher than those of TiO2 nanobelts and In2O3 nanoparticles alone. Moreover, the In2O3 nanoparticle/TiO2 nanobelt heterostructure shows an enhanced PEC performance under irradiation of visible light. The enhanced photocatalytic and PEC activities are mainly ascribed to the synergic effect of efficient charge separation of heterostructure, visible-light harvesting ability of In2O3, and the formation of preferential adsorption sites by the small size of In2O3 nanoparticles. Finally, based on the experimental results of Mott-Schottky, UV-vis DRS, photocurrent and open-circuit voltage response, a possible photocatalytic mechanism over the In2O3 nanoparticle/TiO2 nanobelt heterostructure is proposed.

Adsorption and intercalation of organic pollutants and heavy metal ions into MgAl-LDHs nanosheets with high capacity

Hexagonal MgAl layered double hydroxide (MgAl-LDH) materials comprised of nanosheets and microsheets with different precipitants were synthesized via a facile hydrothermal route. XRD, FESEM, TEM and BET were employed to characterize the samples. Structural characterization revealed that MgAl-LDHs nanosheets and microsheets are 100 nm and 2 μm in width, respectively. Furthermore, MgAl-LDHs nanosheets have a higher specific surface area (65.94 m2 g−1) than that of microsheets (15.75 m2 g−1). Methyl orange and Cr(VI) anion and Ni(II) cation adsorption on the as-synthesized MgAl-LDHs nanosheets and microsheets were systematically assessed by measuring the residual concentration during the adsorption process. The MgAl-LDHs nanosheets showed better adsorption performance than the MgAl-LDHs microsheets for methyl orange and Cr(VI) anions and Ni(II) cations. The adsorption performance versus time for the adsorption of methyl orange by MgAl-LDHs nanosheets has an excellent adsorption quantity (229.82 mg L−1) with high adsorption rate. The adsorption kinetics and adsorption isotherms of Cr(VI) anions and Ni(II) cations of MgAl-LDHs nanosheets can be described by the pseudo-second order kinetic and Langmuir isotherm with saturated adsorption of 63.8 and 92.3 mg g−1, respectively. Combined with results from XRD, FTIR, EDS and XPS experiments, the adsorption mechanisms of MgAl-LDHs nanosheets including precipitation, surface complexation, isomorphic substitution and ion exchange in the interlayer space of MgAl-LDHs nanosheets are discussed in detail. Finally, based on the quick and efficient removal of heavy metal ions by MgAl-LDHs nanosheets, a filtering-type water purification device was constructed.

Highly efficient photocatalytic activity of Ag3PO4/Ag/ZnS(en)0.5 photocatalysts through Z-scheme photocatalytic mechanism

A novel Z-scheme Ag3PO4/Ag/ZnS(en)0.5 composite material was successfully prepared via a facile hydrothermal method and in situ precipitation. The composites exhibit significantly improved visible light photostability and photocatalytic activity towards methylene blue (MB) and phenol degradation. The excellent performance is mainly ascribed to the Z-scheme system formation of a Ag3PO4, Ag, and ZnS(en)0.5 hybrid. This system does not only enhance the photogenerated electron–hole pairs separation and transfer efficiency, but also maintains strong oxidation and reduction as well. This study may provide new insights to understand and design Z-scheme photocatalysts with high photoactivity.