Facet engineering of α-MnO2 for directly electrocatalytic oxygen atom transfer from water toward epoxidation

Electrocatalytic epoxidation, utilizing sustainable water and electricity as clean oxygen source and chemical oxidant surrogates respectively, represents an attractive approach toward industrial applications. However, the low yield and selectivity of epoxides are still a formidable challenge in satisfying industrial demand. Herein, we demonstrated a crystal facet engineering strategy over α-MnO2 catalysts for enhancing electrocatalytic epoxidation. Compared with α-MnO2-110 and α-MnO2-100, the α-MnO2 exposed with (3 1 0) facet exhibited excellent activity. Furthermore, a 21-fold yield increase was obtained compared with the reported superior Mn-based electrocatalyst. These results revealed that crystal facet engineering could induce the formation of more oxygen vacancies and weaken the interaction of Mn-O band to regulate oxygen atom transfer capacity. In addition, the reactive intermediate (MnOOH) was observed in an organic electrolyte, which was confirmed by in situ Raman spectra and isotope labeling experiment.