Interfacial Engineering of BiVO₄/Bi₂Mo₂O₉ Heterojunction Toward Photogenerated Carriers Anisotropic Transfer

Abstract

Developing an advanced strategy to decrease the charge recombination of BiVO4 is a vital requirement to boost charge transfer for photoelectrochemical water oxidation. Herein, a type II BiVO4/Bi2Mo2O9 heterojunction is successfully synthesized on fluorine‐doped tin oxide substrate by successive ionic layer adsorption and reaction method. Thanks to the Fermi‐level energy difference of 275 mV between BiVO4 and Bi2Mo2O9, an outward built‐in electric filed pointing from Bi2Mo2O9 to BiVO4 is induced, which accelerates the directional flowing of photogenerated electron and hole. Such a unique design structure fastens the electron migration from BiVO4 to Bi2Mo2O9, and the holes will transfer to the surface to participate in water oxidation. The longer lifetime (9.2 ns) by time‐resolved transient photoluminescence signifies that the Bi2Mo2O9 can boost interfacial carriers’ anisotropic migration; the surface charge transfer rate of BiVO4/Bi2Mo2O9 is up to 387.6 s−1 (1.4 V vs reversible hydrogen electrode (RHE)). The BiVO4/Bi2Mo2O9 heterojunction exhibits a remarkable charge separation efficiency of 64% and outstanding photocurrent density of 0.9 mA cm−2 at 1.23 V versus RHE.