Efficient photocatalytic water splitting of BiFeO3–BaTiO3 as a perovskite based n-n heterojunction toward H2 evolution without using sacrificial agent

Construction of heterostructure photocatalysts is an effective strategy to achieve charge separation and enhance photocatalytic activity. Herein, perovskite-based n-n heterostructure of BiFeO3–BaTiO3 was prepared and applied for water splitting process with the aim of H2 production. The slope of Mott-Schottky plots revealed that both BiFeO3 and BaTiO3 are n-type photocatalysts with flat band potentials of +0.67 and −0.03 eV, respectively. The flat band potential of BaTiO3 meets the potential required for reducing H+ to H2. However, the results of PL and EIS demonstrated the high recombination rate of charge carriers in pure BaTiO3. By introducing BiFeO3 and construction of n-n heterostructures, the charge separation and mobility were promoted as a result of charge transfer process. Based on the Fermi level positions, difference of the work function between the two photocatalysts, and the radical scavenger experiments results, the direct Z-scheme charge transfer mechanism is suggested in BiFeO3–BaTiO3 heterojunction. The best photocatalytic H2 evolution under UV–vis irradiation and without using sacrificial agent was obtained to be 328 μmol g−1 h−1 by a heterostructure composed of 70 wt % BFO.