EFFICIENT PHOTOELECTROCHEMICAL REDUCTION OF CARBON-DIOXIDE ON A P-TYPE SILICON (P-SI) ELECTRODE MODIFIED WITH VERY SMALL COPPER PARTICLES

The photoelectrochemical reduction of CO2 was performed with p-type si licon (p-Si) electrodes modified with very small Cu particles. Hydroca rbons such as methane and ethylene were produced together with CO and HCOOH similar to the case of a Cu-metal electrode, but at potentials c a. 0.4 V more positive than the Cu-metal electrode, clearly showing th at the photovoltage generated in the p-Si is effectively utilized for the CO2 reduction. On the contrary, p-Si electrodes coated with contin uous Cu layers as well as naked p-Si electrodes showed no such photo-s hifts in potential.