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

A cobalt-phosphate based oxygen evolution catalyst (Co-PiOEC) was electrochemically deposited onto the surface of a porous bismuth vanadate electrode doped with 2 atom% Mo (BiV0.98Mo0.02O4). The porous BiV0.98Mo0.02O4 electrode was prepared using a surfactant assisted metal-organic decomposition technique at 500 degrees C. The comparison of the photocurrent-voltage characteristics of the BiV0.98Mo0.02O4 electrodes with and without the presence of Co-Pi catalyst demonstrated that the Co-Pi catalyst enhanced the anodic photocurrent of the BiV0.98Mo0.02O4 electrode with its effect more pronounced at lower potentials. A stable photocurrrent density of 1.0mA cm(-2) at 1.0V 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 BiV0.98Mo0.02O4 electrode, a sustained enhancement, nearly doubled photocurrent density was observed at 1.0V vs. Ag/AgCl for Co-Pi/BiV0.98Mo0.02O4 composite photoelectrode. Significant performance gains are obtained on BiV0.98Mo0.02O4 electrodes upon modification with Co-Pi water oxidation catalyst.