Bi2S3–In2S3 Heterostructures for Efficient Photoreduction of Highly Toxic Cr6+ Enabled by Facet‐Coupling and Z‐Scheme Structure

The construction of Z-scheme photocatalyst materials mimicking the natural photosynthesis system provides many advantages, including increased light harvesting, spatially separated reductive and oxidative active sites and strong redox ability. Here, a novel Bi₂ S₃ nanorod@In₂ S₃ nanoparticle heterojunction photocatalyst synthesized through one-pot hydrothermal method for Cr⁶⁺ reduction is reported. A systematic investigation of the microstructural and compositional characteristics of the heterojunction catalyst confirms an intimate facet coupling between (440) crystal facet of In₂ S₃ and (060) crystal facet of Bi₂ S₃ , which provides a robust heterojunction interface for charge transfer. When tested under visible-light irradiation, the Bi₂ S₃ -In₂ S₃ heterojunction photocatalyst with 15% Bi₂ S₃ loading content achieves the highest Cr⁶⁺ photoreduction efficiency of nearly 100% with excellent stability, which is among the best-reported performances for Cr⁶⁺ removal. Further examination using optical, photoelectrochemical, impedance spectroscopy, and electron spin resonance spectroscopy characterizations reveal greatly improved photogenerated charge separation and transfer efficiency, and confirm Z-scheme electronic structure of the photocatalyst. The Z-scheme Bi₂ S₃ -In₂ S₃ photocatalyst demonstrated here presents promise for the removal of highly toxic Cr⁶⁺ , and could also be of interest in photocatalytic energy conversion.