Morphology Engineering of BiVO4 with CoOx Derived from Cobalt-containing Polyoxometalate as Co-catalyst for Oxygen Evolution.

Abstract

Bismuth vanadate (BiVO4 ) as a metal oxidation semiconductor has stimulated extensive attention in the photocatalytic water splitting field. However, the poor transport ability and easy recombination of charge carriers limit photocatalytic water oxidation activity of pure BiVO4 . Herein, the photocatalytic activity of BiVO4 is enhanced via adjusting its morphology and combination co-catalyst. First, the Cu-BiVO4 was synthesized by copper doping to control the growth of {110} facet of BiVO4 , which is regarded for the separation of photo-generated charge carriers. Then the CoOx in-situ generated from K6 [SiCoII (H2 O)W11 O39 ] ⋅ 16H2 O was photo-deposited on Cu-BiVO4 surface as co-catalyst to speed up reaction kinetics. Cu-BiVO4 @CoOx hybrid catalyst shows highest photocatalytic activity and best stability among all the prepared catalysts. Oxygen evolution is about 34.6 μmol in pH 4 acetic acid buffer under 420 nm LED irradiation, which is nearly 20 times higher than that of pure BiVO4 . Apparent quantum efficiency (AQE) in 1 h and O2 yield are 1.83% and 23.1%, respectively. O2 evolution amount nearly maintains the original value even after 5 cycles.