Enhanced photocatalytic degradation of organic pollutants and hydrogen production by a visible light–responsive Bi<inf>2</inf>WO<inf>6</inf>/ZnIn<inf>2</inf>S<inf>4</inf> heterojunction

Abstract

In this work, we have reported the photocatalytic applications of the direct Z-scheme Bi2WO6/ZnIn2S4 heterojunction in the degradation of organic pollutants and the production of H2 gas. The nano-spherical shape of Bi2WO6 and porous structure of ZnIn2S4 particles, synthesized using cyclic microwave radiation method, facilitated the intimate interfacial contact of the heterojunction. Consequently, the photocatalytic activity of Bi2WO6/ZnIn2S4 towards degradation of salicylic acid (SA) and methylene blue (MB), the models of non-dye and dye organic pollutants, were maximized after introducing only 12.5%wt of Bi2WO6. Similarly, this photocatalyst demonstrated an enhancement in H2 production in comparison to the single-component photocatalysts. Furthermore, this photocatalyst maintained a high photoactivity after three repeated cycles for MB degradation and H2 production. The enhanced photo-efficacy of this heterojunction originates from the improved separation and transportation of photogenerated e−/h+ through a direct Z-scheme system. This was evidenced by electrochemical analyses and active species trapping experiments, combined with the consideration of reduction potential of reactive oxygen species.