Recently, the Research group of Prof. Shiqiang Wei from National synchrotron Radiation Laboratory, University of Science and Technology of China has made great progress in the investigation of structure and performance correlations of two-dimensional CoOOH photocatalytic functional materials by means of synchrotron radiation X-ray absorption spectroscopy technique. This work has been published on Angew. Chem. Int. Ed. (2015, 54, 8722) with the title of “CoOOH Nanosheets with High Mass Activity for Water Oxidation”.
Water splitting to generate hydrogen and oxygen assisted by electricity or sunlight has long been studied as a potential means of clean, large-scale fuel production. To complete the complex four-electron half reaction of water oxidation, noble metal oxides of IrO₂ and RhO₂ are usually employed as the oxygen evolution electrocatalysts, but the practical application is limited by their scarcity and expensiveness. Therefore, finding a high efficient and low cost transition-metal oxide (TMO) based electrocatalyst for water oxidation is urgently important and becomes a key theme of current renewable energy research. In this work, we present an atomically thin cobalt oxyhydroxide (γ-CoOOH) nanosheet as an efficient electrocatalyst for water oxidation. The 1.4 nm thick γ-CoOOH nanosheet electrocatalyst can effectively oxidize water with extraordinarily large mass activities of 66.6 A/g, 20 times higher than that of γ-CoOOH bulk and 2.4 times higher than that of the benchmarking IrO₂ electrocatalyst. X-ray absorption spectroscopy and first-principles calculations provide solid evidence to the half metallic nature of the as-prepared nanosheets with local structure distortion of the surface CoO_6−x octahedron. This greatly enhances the electrophilicity of H₂O and facilitates the interfacial electron transfer between Co ions and adsorbed –OOH species to form O₂, resulting in the high electrocatalytic activity of layered CoOOH for water oxidation. Our γ-CoOOH nanosheets results provide prospective insights into the design of high performance electrocatalysts for water oxidation electrocatalysis.
This work was supported by the National Natural Science Foundation of China, the National Basic Research Program of China, and the Foundation for Innovative Research Groups of the National Natural Science Foundation of China.