Direct Growth of BiVO₄/Bi₂S₃ Nanorod Array on Conductive Glass as Photocatalyst for Enhancing the Photoelectrochemical Performance

Abstract

Photoelectrochemical water splitting is one of the promising methods to generate hydrogen fuels. Designing photocatalysts for accelerating four-electron transfer water oxidation is necessary to improve photoelectrochemical water splitting. Bismuth vanadate is one of the efficient photocatalysts for water oxidation, but the short diffusion length limits its photocatalytic ability. This work first proposes synthesis of bismuth sulfide/bismuth vanadate nanorod array on conducting glass via solution method and hydrothermal reaction to enhance visible-light absorption and provide efficient charge-transfer with type II heterojunction and one-dimensional transfer path. Bismuth sulfide coverage on bismuth vanadate nanorod array is simply tuned by varying thiourea amounts in hydrothermal solution. Higher photocurrent density of 1.43 mA/cm2 are obtained for bismuth sulfide/bismuth vanadate electrode than that for bismuth vanadate electrode (0.25 mA/cm2) at 1.23 V versus reversible hydrogen electrode, measured under air mass 1.5 global illumination in 0.5 M sodium sulfate electrolyte. A negatively shifted onset potential and enhanced stability are attained for bismuth sulfide/bismuth vanadate electrode coupled with cobalt phosphate cocatalyst due to reduced surface charge recombination. This study applies morphology construction, heterojunction establishment, and cocatalyst incorporation to enhance the photocatalytic ability of BiVO4-based electrodes, suggesting the careful design of photocatalysts is significant to improve photoelectrochemical water splitting.