Breaking the Scaling Relationship on Single-Atom Embedded MBene for Selective CO₂ Electroreduction

Highly active and selective electrochemical CO2 reduction reaction (CO2RR) to chemicals and fuels is crucial for clean energy production and environmental remediation. Although transition metals and their alloys are widely used to catalyze CO2RR, 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 CO2RR. We predict that single transition metal atoms embedded in two-dimensional Mo2B2 could be exceptional catalysts for CO2RR. 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-Mo2B2 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.