Dynamic chromium dopant promotes interfacial water activation on cobalt spinel oxide for efficient oxygen evolution in acid.

Although cobalt spinel oxide-based catalysts have demonstrated promising performance for the oxygen evolution reaction in acid, strategies reported have largely focused on manipulating the binding energies of reaction intermediates through tailoring the inherent electronic structures. The role of interfacial water structures on the electrode surface in promoting the acidic oxygen evolution reaction performance through controlled water activation has been largely overlooked. Here we show that introducing chromium dopant into cobalt spinel oxide can simultaneously increase the activity and stability by promoting interfacial water dissociation and dynamic electron transfer. The chromium dopant can not only dynamically regulate the electronic structure of cobalt and mitigate the over-oxidation of active cobalt sites at high overpotential, but also enhance the coverage of hydroxyl species on the catalyst surface, thereby optimizing the interfacial water structure, accelerating the reactant free-water supply and promoting subsequent interfacial water dissociation. Consequently, the obtained catalyst demonstrates enhanced performance in both solution electrocatalysis and device electrocatalysis. This work provides a comprehensive understanding of enhancing the acidic oxygen evolution reaction performance by promoting interfacial water dissociation.