  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 activates
the MoSi2N4 inert basal-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.
