How 3d Transition Metal Elements Determine the Oxygen Evolution Activity in Ni(OH) 2 Matrix

Abstract

3d transition metals have been investigated as active centers in Ni(OH)2 to catalyze oxygen evolution reaction (OER), while conflicts of mechanism still exist. Herein, we studied how Ni, Co and Fe determine the OER activity in atomically thin Ni(OH)2 via experiments and theoretical calculations. The results show that both Co and Fe, with enhanced density of states near the Fermi level, decrease the overpotential by increasing the binding energy of O* and consequently exhibit higher catalytic activities than Ni. In particular, Fe, with nearly optimal O* binding energy, exhibits the lowest overpotential of 181 mV to reach 50 mA cm-2. In the case of CoFe co-doping, Co alters the electronic states of Fe, which weakens the Fe-OOH bond and slightly increases the overpotential. Based on the calculated activities, an overpotential contour plot is constructed, providing guidance for rational catalyst design via modulating electronic structures and intermediate binding energies.