Selenium vacancy triggered atomic disordering of Co0.85Se nanoparticles towards a highly-active electrocatalyst for water oxidation

Abstract

Selenium vacancy engineering has been realized in Co_0.85Se nanoparticles via an anoxic melting strategy, where the vacancy content can be continuously controlled to modulate atomic disordering. The resulting Co_0.85Se-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 (j_Co = 6.49 A g⁻¹ at η = 270 mV) and lowest apparent activation energy (42.43 kJ mol⁻¹).