Improved Photocatalytic O2 Evolution on a Sillen-Aurivillius Perovskite Oxychloride Bi6NbWO14Cl by Rh2O3 Additives and Surface Modifications

oxyhalide, Bi6NbWO14Cl, was recently reported as a stable and efficient O-2-evolving photocatalyst for Z-scheme water splitting, even without any modifications. However, efforts have not yet been made to improve its photocatalytic activity. In this study, we synthesized a Bi6NbWO14Cl photocatalyst using Rh(2)O(3 )additives and modified its surface with Rh species to improve its photocatalytic activity. An appropriate amount of the Rh2O3 additive significantly enhanced the O-2 evolution rate on Bi6NbWO14Cl from the aqueous AgNO3 solution, likely owing to enhanced charge transfer by the metallic Rh nanoparticles formed around the grain boundaries. In addition, surface modification with Rh species led to a further enhancement of the O-2 evolution rate. The apparent quantum efficiency of the O-2 evolution reached 11% at 420 nm, which is the best reported performance for oxyhalides prepared by solid-state reactions. These Rh species were characterized by X-ray absorption fine structure, X-ray photoelectron spectroscopy, and transmission electron microscopy, and their roles in the enhanced photocatalytic activities were discussed.

Automated summary

In this study, a Bi6NbWO14Cl photocatalyst was synthesized using Rh(2)O(3) additives and its surface was modified with Rh species to improve its photocatalytic activity. The addition of an appropriate amount of Rh2O3 significantly enhanced the O-2 evolution rate on Bi6NbWO14Cl, likely due to enhanced charge transfer by metallic Rh nanoparticles. Surface modification with Rh species further enhanced the O-2 evolution rate, achieving an apparent quantum efficiency of 11% at 420 nm, the best reported performance for oxyhalides prepared by solid-state reactions. The roles of these Rh species in the enhanced photocatalytic activities were discussed.