In Situ Growth of Nanostructured BiVO4-Bi2O3 Mixed-Phase via Non-Equilibrium Deposition for Enhanced Photoelectrochemical Water Splitting

Abstract

Despite the advantages of BiVO4 with great light absorption ability and suitable conduction band edge position for water oxidation, poor charge transport properties of BiVO4 have been obstacles to achieve the ideal efficiency of photoelectrochemical water splitting. To overcome this limitation we introduce a distinctive structure of mixed-phase, composed of BiVO4 and β-Bi2O3. The mixed-phase is fabricated via non-equilibrium deposition by adjusted oxygen partial pressure. According to density functional theory calculations, we find that vanadium exsolution can be facilitated by introducing oxygen vacancies, enabling the fabrication of nanostructured mixed-phase. These unique structures enhance charge migration by increasing the interfacial area and properly aligning the band offset between two crystalline phases. Consequently, the photocurrent density of the nanostructured mixed-phase thin films is about twice that of pristine BiVO4 thin films at 1.23 VRHE. Our work suggests that non-equilibrium deposition provides an innovative route for the in situ structural engineering of photoelectrodes for the understanding of fundamental properties and for improving photocatalytic performance for solar water splitting.