Triggering the Direct C-C Coupling of Gaseous CO into C2 Oxygenates by Synergizing Interfacial Interactions and Reversible Spatial Dynamic Confinement

Controllable C-C coupling is the key to the transformation of Cl molecules into high-value multicarbon (C2+) chemicals. Herein, we report a synergistic mechanism of interfacial metal-support interactions and reversible spatial dynamic confinement that triggers the direct C-C coupling of gaseous CO and further electrical reduction to C-2 products over graphene-coating copper-base Gr/Cu(111) electrodes. The interfacial interaction and spatial distance of Gr/Cu(111) dynamically changed by making the interfacial C-Cu bonds between graphene and Cu substrate and breaking these bonds. Such dynamic and synergetic effects enabled not only exceptionally high stability in the hydrogenation of the key intermediate O*C*CO but also led the active sites to become highly adaptable toward both reactant adsorption and product desorption, thus boosting the direct C-C coupling of gaseous CO and selectivity of C-2 products. The Gr/Cu(111) electrode surface was favorable for the formation of two-carbon-chemisorbed key intermediate O*C*CO that was formed from two gaseous CO monomers via a metastable intermediate of O*CCO with an energy barrier of 0.94 eV. The O*C*CO and O*CCO configurations chemisorbed on Gr/Cu(111) exhibited a negative univalent [C2O2](-), which was more stable than neutral C2O2. The electroreduction pathway of O*C*CO indicates that the formation of acetaldehyde (CH3CHO) was preferred due to the lowest formation free energy of 0.20 eV, while CH2CH2 and CH3CH2OH were considerably competitive products because their formation free energies were only similar to 0.04 eV higher than that of acetaldehyde. The results revealed that such an interfacial dynamic effect granted high catalytic performance, providing an avenue to rationally design novel catalysts and controllable C-C coupling for the electroreduction of CO2 or CO.

Automated summary

This study reports a synergistic mechanism involving interfacial metal-support interactions and reversible spatial dynamic confinement for the direct C-C coupling of gaseous CO and subsequent electrical reduction to C-2 products over a graphene-coating copper-base electrode. The dynamic change in the interfacial interaction and spatial distance between graphene and copper substrate enables high stability in the reaction and promotes the formation of C-2 products. These findings provide insights for the rational design of novel catalysts for the electroreduction of CO2 or CO.