Plasma-induced oxygen vacancies in amorphous MnOx boost catalytic performance for electrochemical CO2 reduction

Recently, oxygen vacancy engineering represents a new direction for rational design of high-performance catalysts for electrochemical CO2 reduction (CO2RR). In this work, a series of amorphous MnOx catalysts with different concentrations of oxygen vacancies, namely, low (a-MnOx-L), pristine (a-MnOx-P), and high oxygen vacancy (a-MnOx-H), have been prepared by simple plasma treatments. The resultant a-MnOx-H catalyst with a larger amount of oxygen vacancy on the catalyst surface is able to preferentially convert CO2 to CO with a high Faradaic efficiency of 94.8% and a partial current density of 10.4 mA cm−2 even at a relatively lower overpotential of 510 mV. On the basis of detailed experimental results and theoretical density functional theory (DFT) calculations, the enhancement of CO production is attributable to the abundant oxygen vacancies formed in the amorphous MnOx which should favor CO2 adsorption/activation and promote charge transfer with the catalyst for efficient CO2 reduction.