Limiting factors for photochemical charge separation in BiVO4/Co3O4, a highly active photocatalyst for water oxidation in sunlight

摘要

Chemical modification of BiVO4 nanoparticies (Scheelite, E_G = 2.62 eV) with chemically deposited Co3O4 nanoparticles improves the photocatalytic water oxidation activity by a factor of 17 to 11 mmol g~(-1) h~(-1) under visible light (AQE 10% at 435 nm) and to 1.24 mmol g~(-1) h~(-1) under sunlight from aqueous 0.02 M Nal04. This activity ranks among the highest among known visible light driven water oxidation photocatalysts. Based on systematic electrochemical, photoetectrochemical, and surface photovoltage measurements, the high photocatalytic activity can be attributed to the electrocatalytic properties of the Co3O4 cocatalyst and to the formation of a heterojunction at the BiVO4-Co3O4 interface.