Photoelectrochemical Properties and Photostabilities of High Surface Area CuBi2O4 and Ag-Doped CuBi2O4 Photocathodes

Abstract

Electrochemical synthesis methods were developed to produce CuBi2O4, a promising p-type oxide for use in solar water splitting, as high surface area electrodes with uniform coverage. These methods involved electrodepositing nanoporous Cu/Bi films with a Cu:Bi ratio of 1:2 from dimethyl sulfoxide or ethylene glycol solutions, and thermally oxidizing them to CuBi2O4 at 450 °C in air. Ag-doped CuBi2O4 electrodes were also prepared by adding a trace amount of Ag+ in the plating medium and codepositing Ag with the Cu/Bi films. In the Ag-doped CuBi2O4, Ag+ ions substitutionally replaced Bi3+ ions and increased the hole concentration in CuBi2O4. As a result, photocurrent enhancements for both O2 reduction and water reduction were achieved. Furthermore, while undoped CuBi2O4 electrodes suffered from anodic photocorrosion during O2 reduction due to poor hole transport, Ag-doped CuBiO4 effectively suppressed anodic photocorrosion. The flat-band potentials of CuBi2O4 and Ag-doped CuBi2O4 electrodes prepared in this ...