Gaining mechanistic insights into the active site is essential to rational design of a high-performance cathode catalyst for the electrochemical CO2 reduction reaction (CO2 RR). Here, by means of density functional theory and computational hydrogen electrode methods, we investigated synergy of a metallic NiCo dimer anchored on a C2N graphene matrix for promoting the CO2 RR. It is found that heterometallic NiCo@C2N (U L = −0.25 V) outperforms homometallic Co2@C2N (U L = −0.30 V) and Ni2@C2N (U L = −0.67 V) for catalyzing the CO2 RR toward CH4 formation owing to its synergy within the dimer. We emphasize the impact of co-adsorbed *H, *OH, and *CO intermediates on the CO2 RR, revealing that multiple competing reaction channels are accessible from viable co-adsorbates. Moreover, strongly-bound *H, *OH, and *CO intermediates are predicted not to deactivate metallic dimer sites for a continuous cycle of the CO2 RR. Our study could provide a theoretical basis for optimizing a metallic dimer anchored on a N-doped graphene matrix for achieving a more advanced CO2 RR cathode with enhanced activity and selectivity.

No abstract

The mechanistic understanding of hydrogenolysis of asymmetric C aryl −O−C alkyl bonds is key to the rational design of high-performance catalysts for bio-oil upgrading. Herein, we theoretically explore hydrodeoxygenation (HDO) of anisole, a prototypical model compound for lignin-derived bio-oils, over homogeneous NiFe(111)-and PtFe(111)-alloyed surfaces within the framework of density functional theory. Our results demonstrate that hydrogenation (HY)/dehydrogenation serves as a molecular mediator for weakening/strengthening the electron delocalization of C aryl /C alkyl atom in a contradicted fashion, which consequently enables facile C aryl −O/O−C alkyl bond cleavage. Especially, the partial HY followed by deoxygenation (PHDO) via a C alkyl −OCH 3 bond scission dominates in demethoxylation kinetics toward benzene formation over direct deoxygenation via a C aryl −OCH 3 bond scission. Indirect demethylation of anisole via the C aryl O−CH 3−x bond scission (x = 1 and 2) is kinetically nearly equivalent to PHDO, leading to comparable formation of phenol and benzene on NiFe(111), but is kinetically more competitive than PHDO, leading to more phenol than benzene formation on PtFe(111). Our results highlight the importance of unbalanced measures that are essential for enhancing asymmetric C aryl −O−C alkyl bond scissions populated in bio-oil upgrading, whereby the implication for catalyst design is generated.