Modifying redox properties and local bonding of Co(3)O(4) by CeO(2) enhances oxygen evolution catalysis in acid

Developing efficient and stable earth-abundant electrocatalysts for acidic oxygen evolution reaction is the bottleneck for water splitting using proton exchange membrane electrolyzers. Here, we show that nanocrystalline CeO(2) in a Co(3)O(4)/CeO(2) nanocomposite can modify the redox properties of Co(3)O(4) and enhances its intrinsic oxygen evolution reaction activity, and combine electrochemical and structural characterizations including kinetic isotope effect, pH- and temperature-dependence, in situ Raman and ex situ X-ray absorption spectroscopy analyses to understand the origin. The local bonding environment of Co(3)O(4) can be modified after the introduction of nanocrystalline CeO(2), which allows the Co(III) species to be easily oxidized into catalytically active Co(IV) species, bypassing the potential-determining surface reconstruction process. Co(3)O(4)/CeO(2) displays a comparable stability to Co(3)O(4) thus breaks the activity/stability tradeoff. This work not only establishes an efficient earth-abundant catalysts for acidic oxygen evolution reaction, but also provides strategies for designing more active catalysts for other reactions.