Enhanced photocatalytic degradation of organic pollutants and hydrogen production by a visible light-responsive Bi2WO6/ZnIn2S4 heterojunction

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 H-2 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 H-2 production in comparison to the single-component photocatalysts. Furthermore, this photocatalyst maintained a high photoactivity after three repeated cycles for MB degradation and H-2 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.

Automated summary

This study reports the photocatalytic applications of the direct Z-scheme Bi2WO6/ZnIn2S4 heterojunction in the degradation of organic pollutants and the production of H-2 gas. The photocatalyst showed high photoactivity and an enhancement in H-2 production, maintaining its efficacy even after multiple repeated cycles. The improved photo-efficacy of this heterojunction is attributed to the enhanced separation and transportation of photogenerated e(-)/h(+) through a direct Z-scheme system.