Selenium vacancy triggered atomic disordering of CoSe nanoparticles towards a highly-active electrocatalyst for water oxidation.

Selenium vacancy engineering has been realized in Co0.85Se nanoparticles via an anoxic melting strategy, where the vacancy content can be continuously controlled to modulate atomic disordering. The resulting Co0.85Se-30 catalyst requires a super low overpotential of 243 mV to achieve 10 mA cm-2 for the OER with a Tafel slope of 45.5 mV dec-1 and 70 h stability. In-depth electrochemical analysis finds that the outstanding properties are chiefly attributed to the dynamic Co-centers, giving the highest intrinsic activity (jCo = 6.49 A g-1 at η = 270 mV) and lowest apparent activation energy (42.43 kJ mol-1).