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

Abstract

Recently, oxygen vacancy engineering represents a new direction for rational design of high-performance catalysts for electrochemical CO 2 reduction (CO 2 RR). In this work, a series of amorphous MnO x catalysts with different concentrations of oxygen vacancies, namely, low (a-MnO x -L), pristine (a-MnO x -P), and high oxygen vacancy (a-MnO x -H), have been prepared by simple plasma treatments. The resultant a-MnO x -H catalyst with a larger amount of oxygen vacancy on the catalyst surface is able to preferentially convert CO 2 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 MnO x which should favor CO 2 adsorption/activation and promote charge transfer with the catalyst for efficient CO 2 reduction. • A class of oxygen vacancies-engineered amorphous MnO x via plasma treatments has been developed for CO 2 RR. • The high concentrations of oxygen vacancies endow a-MnO x -H catalysts with high catalytic performance. • Detailed experimental results and DFT calculations prove the greatly enhanced CO 2 RR performance of a-MnO x -H.