The Catalytic Effect of Electrodeposited Metals on the Photo‐Reduction of Water at p‐type Semiconductors

Abstract

The electrochemical behaviors of semiconductor electrodes on which a very small amount of metal is electrodeposited have been studied. The cathodic photocurrent‐potential curve for the p‐type GaP or Si electrode is shifted to the 0.2–0.3V more positive potential by the deposition of platinum. The cathodic current‐potential curve for the n‐type GaP electrode is also shifted similarly, but the anodic current‐potential curves and the flat band potentials for both the p‐ and n‐GaP electrodes are not changed. From these results and those on the effects of other metals (Pd, Ni or Cu), it is concluded that the above‐mentioned shifts are due to the catalytic actions of the deposited metals on the hydrogen evolution reaction at the semiconductor electrodes. A tentative model explaining this effect is presented.