Hierarchical assembly of In 2 O 3 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 In2 O3 nanoparticles was prepared using a hydrothermal method combined with an annealing treatment via carbon fiber (CF) templates. Experimental results reveal that the In2 O3 /ZnO hierarchical composite has a tubular structure with an average diameter of ∼6μm and In2 O3 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 In2 O3 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 In2 O3 nanoparticles on the ZnO nanorod surfaces, which provide more active sites for pollutants and gases.