PHOTOCHEMICAL WATER OXIDATION TO OXYGEN AT THE SOLID GAS INTERFACE OFAGCL ON ZEOLITE-A/

Silver chloride supported on zeolite A evolves oxygen when irradiated with light of wavelength shorter than about 550 nm in the presence of water-saturated argon. The amount of Ag+ adsorbed on the surface of Ag Cl correlates with the photoreactivity of the system. The concentratio n of Ag+ in the Ag+/Na+ zeolite A cages influences the rate at which o xygen is produced and determines the total amount formed. The reaction depends on the water partial pressure and the system shows self-sensi tisation of the photochemical oxidation of water to oxygen, which mean s that new photoactive colour centres are formed under near UV illumin ation. A mechanism explaining the above findings is discussed. (C) 199 7 Elsevier Science S.A.