Hydrogen and electricity from water and light

Four self-driven photoelectrochemical hydrogen producers: n-TiO₂/p-CdTe, n-TiO₂/p-GaP, n-SrTiO₃/p-CdTe and n-SrTiO₃/p-GaP were constructed and examined in 1 M NaOH. the current-potential curves of the individual electrodes and the current-cell voltage relationships were measured. Cell current-density measurements versus time demonstrated that the output of each cell is stable for at least 12 h. the n-SrTiO₃/p-GaP cell under xenon light irradiation was the most efficient at 0·7 per cent. the n-TiO₂/p-GaP cell was estimated as the most efficient under solar light at 0·1 per cent. the stability of p-CdTe and its energy gap of 1·5 eV make it a prospect for use as a photocathode in future photoelectrochemical hydrogen producers.