Structural and mechanistic studies of tunable, stable, fast multi-cobalt water oxidation catalysts

Abstract

New multi-cobalt-containing polyoxometalates (POMs) are soluble, fast and tunable water oxidation catalysts (WOCs). We report additional studies of [Co4(H2O)2(PW9O34) 2]10- (1), a very fast, soluble and oxidative stable WOC: new kinetics data further indicate that Co2+ is not kinetically important in water oxidations catalyzed by 1. Second, we report a new WOC, [{Co4(μ-OH)(H2O)3}(Si2W 19O70)]11- that coexists in a 1:1 ratio in the solid state (2a and 2b), and while it is oxidatively stable, it is not hydrolytically stable, rearranging to [Co(H2O)SiW11O 39]6- in aqueous solution. All these studies provide insights relating structural, electronic and other features of these WOCs to their reactivity and stability. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).