TOWARDS THE CONSTRUCTION OF A COMPLETE CYCLIC WATER DECOMPOSITION SYSTEM, DESIGN AND OPERATION OF AN OXYGEN PRODUCING HALF CELL

Oxygen is generated when aqueous solution of iron (III) tris(2,2′‐bipyridyl), Fe(bipy) 33+, are brought in contact with catalytic amounts of powdered or colloidal RuO2. The oxygen yield depends strongly on the pH, reaching a maximum between pH 7 and 8 where it corresponds to the stoichiometry of the reaction: (Formula Presented.) The rate of the reaction is so fast that it occurs practically upon dissolution of Fe(bipy) 33+ in the aqueous phase. In acidic media (pH 4), no O2 evolution is observed. Instead, Fe(bipy) 33+ is converted to an intermediate which in the presence of RuO2 yields O2 upon neutralization. The pH profile of the O2 evolution occuring upon illumination of Ru(bipy) 32+ in the presence of the cobalt complex [Co(NH3)5Cl]2+ was also investigated. The surprisingly low energy losses (160 mV) in reaction (1) makes the construction of four quanta water splitting systems feasible. Copyright © 1979 Verlag GmbH & Co. KGaA, Weinheim