Insoluble films of metal oxide or metal salt frequently are formed on the surface of metals immersed in aqueous solutions. These insoluble films, which often have semiconductor properties, play an important role in corrosion reactions. Since semiconductors exhibit photoeffects as a result of electron-hole pair generation, it seems reasonable to expect that photoeffects also would be observed for semiconductor films naturally formed on metals immersed in solutions.
The influence of illumination in the corrosion of copper has been observed by Kruger1 who reported that white light retards the formation of cuprous oxide on copper in air-saturated water. Photopotentials, the Becquerel effect, generated as a result of the illumination of copper-cuprous oxide electrodes in aqueous solutions have been observed by a number of investigators.2 Photoinduced electrode reactions (such as observed by Kruger1 ) and the Becquerel effect of binary semiconductors have been related by Williams.3 His theory...
