There is increasing interesy in utilizing the photoelectrochemical (PEC) effect, an effect that produces a change in electrode potential in an electrode/electrolyte system upon irradiation to transform the solar energy directly into electrical energy or synthetic fuels such as hydrogen. It is a cost effective, carbon neutral direct method for the production of renewable fuel and energy storage. The research interest in this area is centered on the development of new electrode configurations with high efficiency and good stability. Several binary metal oxide semiconductor photoelectrodes have been explored for photoelectrochemical water oxidation. However, the poor efficiencies resulted from their large band gaps limited their application for water splitting. The revival of interest in the development of photoelectrodes is based on production of low visible light active semiconductor electrodes with high surface area, high efficiency and stability. The utilization of ternary oxide materials over the binary metal oxides offers a wide range of advantages and flexibility in designing an efficient photoelectrode material through the possibility of incorporation of multiple cations. Recently, BiVO4 having hybridized O-2p and Bi-6s orbitals contributing to the formation of the valence band has attracted much attention in designing visible light driven water oxidation photoelectrodes.  In order to enhance the efficiency of BiVO4 it is important to enhance the n-type conductivity through doping. It is also important to improve the electrode/electrolyte interfacial area in order to facilitate the charge transfer at the interface. This can be achieved through the incorporation of porosity into the electrode structure. In addition, the charge separation issue can be solved through the integration of another semiconductor with suitable band edges using band edge offset positions. For example, the photogenerated electrons on the BiVO4 can be efficiently separated and transferred if there exists another semiconductor with relatively more positive conduction band edge compared to that of the conduction band of BiVO4.

Modified ternary oxide sysytems for efficent solar driven water oxidation

247th National Meeting (2014)

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