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

Developing an advanced strategy to decrease the charge recombination of BiVO 4 is a vital requirement to boost charge transfer for photoelectrochemical water oxidation. Herein, a type II BiVO 4 /Bi 2 Mo 2 O 9 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 BiVO 4 and Bi 2 Mo 2 O 9 , an outward built‐in electric filed pointing from Bi 2 Mo 2 O 9 to BiVO 4 is induced, which accelerates the directional flowing of photogenerated electron and hole. Such a unique design structure fastens the electron migration from BiVO 4 to Bi 2 Mo 2 O 9 , 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 Bi 2 Mo 2 O 9 can boost interfacial carriers’ anisotropic migration; the surface charge transfer rate of BiVO 4 /Bi 2 Mo 2 O 9 is up to 387.6 s −1 (1.4 V vs reversible hydrogen electrode (RHE)). The BiVO 4 /Bi 2 Mo 2 O 9 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.