Local spin-state tuning of cobalt-iron selenide nanoframes for the boosted oxygen evolution

Hydrogen economy by water splitting is the indispensable cornerstone for sustainable energy yet it is impeded by sluggish anodic water oxidation. Hence, the rational design of highly efficient electrocatalysts for oxygen evolution is the key to unlocking its wider use. Herein, cobalt-iron selenide nanoframes are reported for the efficient water oxidation, which need only 270 mV overpotential to give a 10 mA cm-2 current density and outperforms most cobalt-based catalysts, and even the benchmarked commercial ruthenium oxides (RuO2). More profoundly, iron doping regulates the local spin state of cobalt species, which further accelerates charge transfer and formation of oxygenated intermediates, and consequently contributes to the enhanced oxygen evolution. This work demonstrates a highly efficient oxygen evolution electrocatalyst and may pioneer a promising approach which involves tuning the local electronic structure to achieve the improved electrocatalysis activities in energy conversion technologies.