Dependence of the rate of water oxidation on the support of a molecularly-derived Ir-oxide catalyst

The design of efficient and stable heterogeneous water oxidation catalysts requires a comprehensive understanding of the material properties that determine water oxidation activity. It has been recognized that the accumulation of oxidative charges (holes) on catalytically active sites and the chemical structure of these sites collectively determine activity. However, the hole distribution dynamics and the structure of the active sites are typically correlated; it has been challenging to independently change them, impeding the development of a deeper understanding of their relative importance. To address this challenge, we studied the oxidation of water on a heterogenized dinuclear Ir catalyst supported on different metal oxide supports. We found that the rate of water oxidation exhibits a remarkable dependence on the identity of the support. We rationalize this observation with the distinct abilities of the supporting substrates to redistribute surface holes. Our findings shine light on the key role that the support plays in determining the turnover at the active sites of heterogeneous water oxidation catalysts.