Surface reaction kinetics and bulk charge separation are both critical to the efficiency of solar water splitting. In addi-tion to the well documented surface catalytic effect, the promotion of bulk charge separation upon the loading of cocatalysts has rarely been reported. This paper describes the synergetic enhancement of surface reaction kinetics and bulk charge separation by introducing discrete nano-island p-type Co3O4 cocatalysts onto n-type BiVO4, forming p-n Co3O4/BiVO4 heterojunction with internal electric field to facilitate charge transport. Being highly dispersed on the surface of photoanodes, the nano-island cocatalysts could suppress the formation of recombination centers at the photoanode/cocatalyst interface. This cocatalyst loading method achieved a charge separation efficiency of up to 77% in the bulk and 47% on the surface of catalysts. An AM 1.5 photocurrent of 2.71 mA/cm2 at 1.23 V versus the reversi-ble hydrogen electrode for water oxidation was obtained, which is the highest photocurrent yet reported for cobalt catalyzed undoped BiVO4 photoanodes, with a photocon-version efficiency of 0.659%.

J. Am. Chem. Soc., 2015, DOI: 10.1021/jacs.5b04186

http://pubs.acs.org/doi/pdf/10.1021/jacs.5b04186