CoOOH Nanosheets with High Mass Activity for Water Oxidation

Endowing transition-metal oxide electrocatalysts with high water oxidation activity is greatly desired for production of clean and sustainable chemical fuels. Here, we present an atomically thin cobalt oxyhydroxide (-CoOOH) nanosheet as an efficient electrocatalyst for water oxidation. The 1.4nm thick -CoOOH nanosheet electrocatalyst can effectively oxidize water with extraordinarily large mass activities of 66.6Ag(-1), 20 times higher than that of -CoOOH bulk and 2.4 times higher than that of the benchmarking IrO2 electrocatalyst. Experimental characterizations and first-principles calculations provide solid evidence to the half-metallic nature of the as-prepared nanosheets with local structure distortion of the surface CoO6-x octahedron. This greatly enhances the electrophilicity of H2O and facilitates the interfacial electron transfer between Co ions and adsorbed -OOH species to form O-2, resulting in the high electrocatalytic activity of layered CoOOH for water oxidation.