WO3/BiVO4/BiOCl porous nanosheet composites from a biomass template for photocatalytic organic pollutant degradation

Abstract

We have demonstrated the design and optimization of a three-component WO3/BiVO4/BiOCl heterojunction photocatalyst based on a two-step synthetic route. The porous BiVO4 nanosheets were first prepared by an immersion-calcination method using biomass broomcorn core as template. Then, the prepared porous BiVO4 nanosheets reacted with WCl6 to construct WO3/BiVO4/BiOCl ternary composites by simultaneously producing WO3 and BiOCl nanoflakes on the surface of porous BiVO4 nanosheets through a facile solvothermal process. In this reaction system, the environmental biomass broomcorn core template is beneficial for the formation of a porous structure. Both tungsten (W) and chlorine (Cl) can be provided by one individual precursor WCl6; while the component contents in the composite can be controlled by changing the amount of WCl6. The formed gradient energy-band structure in the ternary composite can lead to gradient charge transfer and migration, which effectively suppresses the recombination of photogenerated charge carriers. The optimal three-component assembly demonstrates improved visible light harvesting and has an increased content of the active sites. The synergetic effects of these advantages caused enhanced photocatalytic activity. The photocatalytic degradation rate toward the RhB of the optimal in composition WO3/BiVO4/BiOCl (12.5 wt%) is approximately 2 and 1.5 times higher than those of BiVO4 and binary BiVO4/BiOCl, respectively.