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 Bi 2 S 3 nanorod@In 2 S 3 nanoparticle heterojunction photocatalyst synthesized through one-pot hydrothermal method for Cr 6+ 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 In 2 S 3 and (060) crystal facet of Bi 2 S 3 , which provides a robust heterojunction interface for charge transfer. When tested under visible-light irradiation, the Bi 2 S 3 –In 2 S 3 heterojunction photocatalyst with 15% Bi 2 S 3 loading content achieves the highest Cr 6+ photoreduction efficiency of nearly 100% with excellent stability, which is among the best-reported performances for Cr 6+ 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 Bi 2 S 3 –In 2 S 3 photocatalyst demonstrated here presents promise for the removal of highly toxic Cr 6+ , and could also be of interest in photocatalytic energy conversion.