In Situ Photoelectrochemical-Induced Surface Reconstruction of BiVO4 Photoanodes for Solar Fuel Production

Abstract

BiVO₄ has been widely concerned due to its great potential in photoelectrochemical (PEC) water splitting. However, low carrier mobilities and high recombination efficiency of photogenerated carriers impede its photocatalytic performance. Herein, an in situ PEC cyclic-voltammetry-induced surface reconstruction of BiVO₄ photoanodes (BVO pristine) is developed with significantly enhanced efficiency for solar water splitting. A series of in situ characterizations (including in situ X-ray diffraction, in situ Raman), together with electrochemical tests and density-functional theory calculations, reveal that during the photoelectrical activation process, the BVO pristine surfaces undergo a crystal plane reconstruction with greatly increased {040} crystal face to promote the separation of photogenerated carriers. In addition, abundant vanadium vacancies and oxygen vacancies are also introduced into the BiVO₄ surface during the crystal face reconstruction process with more favorable surface water adsorption and increased injection efficiency of photogenerated carriers. Therefore, the charge-transfer resistance (R_ct) between BVO pristine and electrolyte under AM 1.5G illumination substantially reduced from the original 15 200 to 2820 Ω after the activation. Moreover, the photocurrent density of activated BVO pristines increases more than 12 times, relative to the original BiVO₄. In this work, a new horizon for in situ photoelectric activation of semiconductor photoelectrodes with significantly enhanced PEC water splitting is provided.