Single-Atom-Anchored Two-Dimensional MoSi2N4 Monolayers for Efficient Electroreduction of CO2 to Formic Acid and Methane

Efficient and selective CO2 electroreduction into value-added chemicals and fuels emerged as a significant approach for CO2 conversion; however, it relies on catalysts with controllable product selectivity and reaction paths. In this work, by means of first-principles calculations, we identify five catalysts (TM@MoSi2N4, TM = Sc, Ti, Fe, Co, and Ni) comprising transition-metal atoms anchored on a MoSi2N4 monolayer, whose catalytic performance can be controlled by adjusting the d-band center and occupation of supported metal atoms. During CO2 reduction, the single metal atoms function as the active sites that activate the MoSi2N4 inert base plane, and as-designed electrocatalysts exhibit excellent activity in CO2 reduction. Interestingly, HCOOH is the preferred product of CO2 reduction on the Co@MoSi2N4 catalyst with a rate-determining barrier of 0.89 eV, while the other four catalysts prefer to reduce CO2 to CH4 with a rate-determining barrier of 0.81-1.24 eV. Moreover, MoSi2N4 is an extremely air-stable material, which will facilitate its application in various environments. Our findings provide a promising candidate with high activity, catalysts for renewable energy technologies, and selectivity for experimental work.