The reconstruction of equal-mole bimetal organic framework to heterostructure for effective oxygen evolution reaction

Abstract

Oxygen evolution reaction (OER) is one of the most important issues for hydrogen production from water splitting. During the OER process, electrochemical reconstruction is widely observed for the majority of electrocatalysts, which is strongly related to the formation and evolution of real active species. Herein, bimetal metal-organic framework (MOF) with an equal ratio of Co and Fe sites is screened to exhibit the superior OER property. An obvious reconstruction is observed to transform single MOF phase into the heterostructure composed of active CoOOH and FeOOH. Meanwhile, the generation of Co3+ species is more reliant on the blessing of electricity and electrolyte than that of Fe3+ species. As a result, the optimal electrocatalyst shows the overpotential of 267 mV at 10 mA/cm2 and ultra-low Tafel slope of 24.7 mV/dec with a stable OER performance.