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.