N–NaTaO_3@Ta_3N_5 Core-Shell Heterojunction with Controlled Interface Boosts Photocatalytic Overall Water Splitting

摘要

Ta_3N_5 is a promising material for photocatalytic hydrogen production fromwater because of its suitable band structure for both solar energy collectionand overall water splitting, while its application is restricted by severe chargerecombination as well as non-equilibrium redox capabilities. Herein,atomic-scale N-doped NaTaO_3@Ta_3N_5 (N–NaTaO_3@Ta_3N_5) core-shell cubesprepared by nitridation of cubic NaTaO_3 are reported. The core-shellheterojunction cubes present efficient and stoichiometric evolution of H_2 andO_2 from photocatalytic overall water splitting, with a quantum efficiency of2.18 at 550 nm without any cocatalyst. The success relies on the Ta3N5 shellhaving a thickness of only ≈5 nm which enables increased lifetimes of thephotogenerated charges. Moreover, the core-shell heterojunction shows atype-I band alignment that can steer smooth charge flow from N–NaTaO_3 toTa_3N_5, particularly with the assistance of the shared communal Ta atoms atthe interface. This efficiency can be further improved to 6.28 by in situdeposition of a Rh@Cr_2O_3 core-shell cocatalyst, which is among the highestreported values over Ta_3N_5-based photocatalyst. This study offers a promisingpathway for the construction of well-defined heterojunctions withmanipulated charge transfer behavior for photocatalytic overall water splitting.