Intrinsic Mechanism Analyses of Significantly Enhanced Photoelectrochemical Performance of the Bi2MoO6/BiVO4 System

In this paper, the electrodeposition and hydrothermal methods were used to prepare the Bi2MoO6/BiVO4 photoelectrode, and the intrinsic mechanism of significantly enhanced photoelectrochemical performance of the prepared Bi2MoO6/BiVO4 heterojunction system was studied. Work functions of Bi2MoO6 and BiVO4 were analyzed using a scanning Kelvin probe, and the direction of the heterojunction electric field and the transfer direction of photogenerated carriers were finally determined by the relative positions of the energy bands and the Fermi levels of Bi2MoO6 and BiVO4. A type II Bi2MoO6/BiVO4 heterojunction system was finally confirmed to be formed. Formation of the type II Bi2MoO6/BiVO4 heterojunction system reduces the recombination efficiency of photogenerated electrons and holes and thus improves the photoelectrochemical performance. The photogenerated current density of the Bi2MoO6/BiVO4 photoelectrode reaches 1.47 mA·cm-2, which is 4.9 times that of pure BiVO4 and thousands of times that of Bi2MoO6. The successful application of a scanning Kelvin probe in the verification of the heterojunction type provides theoretical and technical bases for the design and construction of efficient heterojunctions.