Photogeneration of hydrogen

Abstract

Water-soluble derivatives of benzophenone are readily reduced to the pinacol or alcohol upon irradiation with near-ultraviolet light in aqueous solution. The hydrogen donor can be a simple organic compound (e.g. methane, alcohol, aldehyde, amine, amide, sulphide, ether, carboxylic acid etc.) but not water. In most cases the photochemistry proceeds rapidly with high quantum yield. If an active Pt colloidal catalyst is added to the solution, the intermediary radicals can be used to reduce water to H₂ on the metallic surface. Thus the organic substrate is effectively dehydrogenated under ambient conditions. In some cases the reaction can be used for synthesis of useful organic materials.