Cobalt-phosphate (Co-Pi) catalyst modified Mo-doped BiVO4 photoelectrodes for solar water oxidation

Abstract

A cobalt-phosphate based oxygen evolution catalyst (Co-Pi OEC) was electrochemically deposited onto the surface of a porous bismuth vanadate electrode doped with 2 atom% Mo (BiV_0.98Mo_0.02O₄). The porous BiV_0.98Mo_0.02O₄electrode was prepared using a surfactant assisted metal–organic decomposition technique at 500 °C. The comparison of the photocurrent–voltage characteristics of the BiV_0.98Mo_0.02O₄electrodes with and without the presence of Co-Pi catalyst demonstrated that the Co-Pi catalyst enhanced the anodic photocurrent of the BiV_0.98Mo_0.02O₄electrode with its effect more pronounced at lower potentials. A stable photocurrrent density of 1.0 mA cm⁻² at 1.0 V vs.Ag/AgCl was achieved under standard AM 1.5 illumination using 0.5M Na₂SO₄ aqueous solution in phosphate buffer at pH7. Relative to the BiV_0.98Mo_0.02O₄electrode, a sustained enhancement, nearly doubled photocurrent density was observed at 1.0 V vs.Ag/AgCl for Co-Pi/BiV_0.98Mo_0.02O₄ composite photoelectrode. Significant performance gains are obtained on BiV_0.98Mo_0.02O₄electrodes upon modification with Co-Pi water oxidation catalyst.