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.