Nitrogen Plasma Activates CoMn-Layered Double Hydroxides for Superior Electrochemical Oxygen Evolution.

Abstract

Bimetallic layered double hydroxide is considered an ideal electrocatalytic material. However, due to the poor electrical conductivity of the bimetallic layered structure, obtaining highly active and stable catalysts through facile regulation strategies remains a great challenge. Herein, we use a simple corrosion strategy and nitrogen plasma technology to convert cobalt-based metal-organic frameworks into nitrogen-doped CoMn bimetallic layered double hydroxides (CoMn-LDH). Under the condition of regulating the local coordination environment of the catalytic active site and the presence of rich oxygen vacancy defects, N@CoMn-LDH/CC generates a low overpotential of 219 mV at 10 mA cm-2, which exceeds that of the commercial RuO2 catalyst. Density functional theory calculation shows that nitrogen doping improves the adsorption energy of the Mn site for oxygen evolution intermediates and reduces the reaction energy barrier of the Co site. Meanwhile, experiments and theoretical calculations verify that the mechanism of nitrogen doping regulating the oxygen evolution reaction (OER) follows the lattice oxygen oxidation mechanism, avoiding the collapse of the structure caused by catalyst reconstruction, thus improving the stability of oxygen evolution. This work provides a new simple strategy for the preparation of catalysts for a superior electrocatalytic oxygen evolution reaction.