Enhanced photoelectrolysis of water with photoanode Nb:SrTiO3

The photoelectrolysis of water has been investigated in a photoelectrochemical cell with the single-crystal photoanodes Nb:SrTiO3 (0 mol%, 0.07 mol%, and 0.69 mol%) and the electrolyte Na2SO4 (0.1 M,pH=5.92). The Nb:SrTiO3 anodes (0.07 mol% and 0.69 mol%) show much higher photocurrent density than the pure SrTiO3 anode in several orders of magnitude. The incident photon to current conversion efficiencies at 298.2 nm and an applied potential 1.5 V (versus the saturated calomel electrode) for three Nb:SrTiO3 (0 mol%, 0.07 mol%, and 0.69 mol%) anodes are 0.92%, 15.67%, and 4.32%, respectively. The transmittance spectra of the Nb:SrTiO3 show an obvious optical absorption around 516 nm (similar to2.4 eV). It is interpreted that two-photon process takes part in the charge transfer from the valence band to the conduction band through the intermediate states induced by Nb doping. (C) 2004 American Institute of Physics.