Novel visible light-driven Nb-doped Ta3N5 sensitized/protected by PPy for efficient overall water splitting

We successfully synthesized niobium-doped tantalum nitride sensitized/protected by polypyrrole (Nb-Ta3N5/PPy) for efficient overall photocatalytic water splitting to produce hydrogen and oxygen under visible light. Niobium as a dopant was incorporated into the Ta3N5 lattice to act as an intermediate band between the valence band (VB) and the conduction band (CB) of Ta3N5 to enhance the electron-hole pair separation efficiency, thereby enhancing its photocatalytic activity. PPy, a conducting polymer with an extended pi-pi* conjugated electron system, was used as a sensitizer to enhance the charge transfer efficiency for migration of the photogenerated electrons and holes to its surface to prevent the recombination of the pairs and thus increase their lifetime. The migration of the photogenerated holes to the PPy surface also prevented the self photocorrosion of Ta3N5 (via reaction between the generated holes and nitrides in Ta3N5) in the electrolyte solution and thus enhanced its stability. Therefore, the synthesized Nb-Ta3N5/PPy photocatalyst exhibited very high photocatalytic activity and stability for overall water splitting to produce H-2 and O-2 even under visible light at production rates of 65.1 and 32.8 mu mol g(-1)cat.h(-1), respectively. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.