Aspects of photocatalysis on semiconductors: Photoelectrocatalysis

An overview is given of the essential processes governing heterogeneous photocatalysis on semiconductor surfaces. It is shown that the reactions on the surface of the catalyst are of electrochemical nature and can be described using electrochemical principles. This leads to a quantitative description of the processes. In combination with measurements of charge collection yields and Faradaic efficiencies, or product quantum yields, the reaction rates can be calculated when the spectral dependence of the intensity of the light source is known. Examples are given for transition metal oxide semiconductors such as titanium dioxide and tungsten trioxide.