A device that can convert solar energy into a chemical fuel with good efficiency while also offering high stability and the capability to be constructed with widely available materials using inexpensive processing techniques is urgently needed. Here I describe progress toward promising systems that accomplish overall photoelectrochemical water splitting with an inexpensive oxide-based photoanode (e.g. Fe2O3 WO3, or BiVO4) and a copper (oxide or chalcogenide) photocathode. Recently, advances in reduction of the overpotentials due the passivation of surface states and the application of catalysts have allowed the construction of simple dual-absorber tandem cell. In order to give insight into the electro-optical limitations and to define routes for improvement of these devices, the current-voltage characteristics as well as the spectral responses of the component parts are evaluated based on measured quantum efficiencies (IPCEs), transmittances of the photoanodes, and photon flux on each active area. Finally, the actual performance of devices is evaluated and the benchmark solar-to-hydrogen conversion efficiency (over 3%) for dual-absorber oxide-based solar water splitting is reported. Overall, the simple construction of these devices and their composition from widely available and inexpensive components makes them very promising for future development.

Unassisted solar water splitting with semiconductor oxide photoanode/photocathode tandem cells

247th National Meeting (2014)

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