PHOTOELECTROLYSIS OF WATER AT HIGH CURRENT DENSITY: USE OF LASER LIGHT EXCITATION OF SEMICONDUCTOR-BASED PHOTOELECTROCHEMICAL CELLS.

Results are given for the ultraviolet (351, 364 nm) laser light irradiation of the photoanode (SnO//2, KTa//0//. //7//7Nb//0//. //2//3O//3, SrTiO//3, or TiO//2) in a cell for the light-driven electrolysis of H//2O. Irradiation intensities up to 380 W/cm**2 have been used, and the general finding is that the properties of anode materials are independent of light intensity. Conversion of ultraviolet light to stored chemical energy in the form of H//2/ one-half O//2 from H//2O has been driven at a rate of up to similar 30 W/cm**2. High O//2 evolution rates at the irradiated anodes without change in current-voltage curves is hypothesized to be a consequence of the excess oxidizing power associated with photo-generated holes. A teshissort of hypothesis for H//2 evolution at p-type materials is proposed.