Interfacial Electronic and Structural Reorganization in Mn₂Co₂C/MnO for Enhancing Oxygen Evolution Kinetics and Active Sites

Interface electronic and structural reorganization in metal-based/support catalysts will unlock great potential for realizing their high efficiency electrocatalytic activities. Herein, we employ Mn2Co2C/MnO as a model catalyst to highlight the important role of charge distribution and atomic disorder at the interface for realizing high-performance water splitting. Mn2Co2C/MnO with abundant atomic interfaces was first prepared by the carbonization of Mn3[Co(CN)6]2·9H2O/polyvinyl pyrrolidone via a one-step pyrolysis strategy. Ultraviolet photoelectron spectroscopy in combination with X-ray photoelectron spectroscopy discloses a negative charge transfer from MnO to Mn2Co2C, thus endowing MnO with a high oxidation state, and meanwhile, extended X-ray absorption fine structure further confirms that there also exist disordered Mn/O atoms and/or dangling bonds in the interface region. On the one hand, MnO with a high oxidation state is more electrophilic, which is particularly favorable for initial electrochemical adsorption of OH- for achieving accelerated oxygen evolution reaction (OER) kinetics. On the other hand, the disordered Mn/O atoms and/or dangling bonds in the interface region could act as extra active sites for adsorption and catalysis. Benefiting from the electronic and structural advantages, Mn2Co2C/MnO displays excellent OER performances in terms of a small overpotential (320 mV at 10 mA cm-2), fast kinetics, and robust stability. This work opens the door for deep understanding of the atomic interface-performance relationship in water splitting, and meanwhile, this concept can be extended to design other energy-related electrode materials.