Breaking the Scaling Relationship on Single-Atom Embedded MBene for Selective CO 2 Electroreduction.

Highly active and selective electrochemical CO 2 reduction reaction (CO 2 RR) to chemicals and fuels is crucial for clean energy production and environmental remediation. Although transition metals and their alloys are widely used to catalyze CO 2 RR, their activity and selectivity are generally unsatisfactory, hindered by energy scaling relationships among the reaction intermediates. Herein, we generalize the multisite functionalization strategy to single-atom catalysts in order to circumvent the scaling relationships for CO 2 RR. We predict that single transition metal atoms embedded in two-dimensional Mo 2 B 2 could be exceptional catalysts for CO 2 RR. We show that the single-atoms (SAs) and their adjacent Mo atoms can only bind to carbon and oxygen atom, respectively, thus enabling dual site functionalization to circumvent the scaling relationships. Following extensive first-principles calculations, we discover two SA-Mo 2 B 2 single-atom catalysts (SA = Rh and Ir) that can produce methane and methanol with an ultralow overpotential of -0.32 and -0.27 V, respectively.