Interface Regulation of Bi3TiNbO9/Rh Photocatalysts by Introducing Ultrathin Heterolayer to Enhance Overall Water Splitting

Aurivillius compounds-based photocatalysts have attracted extensive interest largely due to their ferroelectric properties and modifiable characteristics arising from the alternate stacking of structural units. However, the interfacial Schottky barrier between such semiconducting compounds as light absorbers and metallic cocatalysts for hydrogen evolution restrains the transfer of photogenerated electrons, resulting in low photocatalytic overall water splitting activity and stability. Here, an anions-induced surface structure transformation strategy is employed to modulate the interface structure between Bi3TiNbO9 as a typical Aurivillius compound and the cocatalyst Rh by in situ growing ultrathin Bi2MoO6 heterolayer on the surface of Bi3TiNbO9 nanosheets. The introduction of Bi2MoO6 heterolayer lowers the energy barrier near the Bi3TiNbO9 surface, which can facilitate the transfer of the photogenerated electrons from bulk to surface and thus the reduction of Rh cocatalyst for highly active hydrogen production. Compared with the Bi3TiNbO9-Rh photocatalyst, the proportion of low-valence metallic Rh-0 in Bi2MoO6 heterolayer-modified Bi3TiNbO9-Rh (Bi3TiNbO9-Bi2MoO6-Rh) is improved by 7.76%, giving rise to a photocatalytic overall water splitting activity enhancement by a factor of 4.74. This strategy emphasizes the importance of interface regulation in promoting the transfer of photogenerated charge carriers in Aurivillius-type photocatalysts, providing an effective pathway for designing and fabricating high-performance photocatalysts.