Z-scheme In2O3/WO3 heterogeneous photocatalysts with enhanced visible-light-driven photocatalytic activity toward degradation of organic dyes

To effectively decompose the organic dyes in wastewater, a novel all-solid state Z-scheme In2O3/WO3 heterostructured photocatalyst was successfully prepared by loading In2O3 nanoparticles onto WO3 nano-needles through a two-step hydrothermal-solvothermal method. The phase structures, morphologies, chemical compositions, and optical adsorption properties of these photocatalysts were characterized in detail. In the Z-scheme photocatalytic system, the built-in internal electric field can accelerate the recombination of useless photo-generated holes on the VB of In2O3 and electrons on the CB of WO3. The retaining photo-generated charge carriers on the CB of In2O3 and VB of WO3 possess strong redox ability. Therefore, the In2O3/WO3 heterogeneous photocatalysts exhibited remarkably improved photocatalytic activity toward degradation of organic dyes and tetracycline hydrochloride compared to pure WO3 and In2O3 semiconductor materials under visible-light irradiation. The recycling experiments showed that Z-scheme In2O3/WO3 heterogeneous photocatalyst could still degrade 86.6% of methylene blue and 86.4% of rhodamine B even after three cycles, confirming its high photo-stability. The trapping experiments demonstrated that photo-generated holes and center dot O-2(-) were the predominant active species for photocatalytic degradation of organic dyes. Based on the experimental results, a possible photocatalytic mechanism of Z-scheme In2O3/WO3 heterostructure was proposed. This investigation provided a novel approach for construction of efficient heterostructured photocatalysts for wastewater purification.