PHOTOEMISSION AND PHOTOLUMINESCENCE STUDIES OF CATALYZED PHOTOELECTRODE SURFACES FOR HYDROGEN-PRODUCTION

Discontinuous metal layers in the form of microislands on semiconductor photoelectrode surfaces are known to catalyze reactions for hydrogen production in photoelectrochemical cells. In an effort to determine how the metal islands can be made to improve the photoelectrode efficiency, we have applied photoemission and photoluminescence techniques to investigate the size effect of the metal islands on: (1) the generation of the open-circuit photovoltage at the surface; and (2) the surface recombination loss of the photoexcited electrons. The photoemission results indicate that the optimal photovoltage could be produced for a discontinuous metal layer on a suitable semiconductor surface. In the photoluminescence study, the emission due to surface recombination was found to be affected by the metal microislands.