Molecular scaffolding strategy with synergistic active centers to facilitate electrocatalytic CO₂ reduction to hydrocarbon/alcohol

Abstract

A major impediment to the electrocatalytic CO₂ reduction reaction (CRR) is the lack of electrocatalysts with both high efficiency and good selectivity toward liquid fuels or other valuable chemicals. Effective strategies for the design of electrocatalysts are yet to be discovered to substitute the conventional trial-and-error approach. This work shows that a combination of density functional theory (DFT) computation and experimental validation of molecular scaffolding to coordinate the metal active centers presents a new molecular-level strategy for the development of electrocatalysts with high CRR selectivity toward hydrocarbon/alcohol. Taking the most widely investigated Cu as a probe, our study reveals that the use of graphitic carbon nitride (g-C₃N₄) as a molecular scaffold allows for an appropriate modification of the electronic structure of Cu in the resultant Cu-C₃N₄ complex. As a result, the adsorption behavior of some key reaction intermediates can be optimized on the Cu-C₃N₄ surface, which greatly benefits the activation of CO₂ and leads to a more facile CO₂ reduction to desired products as compared with those on the Cu(111) surface and other kinds of Cu complexes formed on nitrogen-doped carbons. Remarkably, different from the most studied elementary metal surfaces, an intramolecular synergistic catalysis with dual active centers was for the first time observed on the Cu-C₃N₄ complex model, which possesses a unique capability to generate C₂ products. A good agreement between electrochemical measurements and the DFT analysis of the CRR has been achieved on the basis of the newly designed and synthesized Cu-C₃N₄ electrocatalyst.