Convergent paired electrosynthesis of dimethyl carbonate from carbon dioxide enabled by designing the superstructure of axial oxygen coordinated nickel single-atom catalysts

Electrochemical CO2 conversion into highly value-added dialkyl carbonate by coupling cathodic CO2 reduction reactions with anodic oxidation reactions is prospective. However, the structures of electrocatalysts should be well conquered for achieving high faradaic efficiency (FE) of dialkyl carbonate. In this work, a dual-channel superstructured Ni single-atom catalyst (SAC) with a unique site coordination configuration bonded via one axial oxygen atom and four planar nitrogen atoms was controllably constructed and is capable of providing a preeminent performance for CO2-to-CO conversion, achieving an exclusively high FE and a partial current density of CO (99% of FE, 325 mA cm(-2)@-0.6 V vs. RHE) with excellent stability. By virtue of the atomic to nano- to micro-scopic manipulation of the pentacoordinated Ni SAC for CO production, the convergent paired electrosynthesis of dimethyl carbonate (DMC) from CO2 was pioneeringly performed, achieving a high FE of DMC up to 80%. The mechanism study unveiled that such axial oxygen coordination configuration is helpful to decrease the energy barriers for the generation of a key *COOH intermediate and the dissociation of H2O and CH3OH, accelerating the convergent paired electrosynthesis. The proof of concept in the innovative convergent paired electrosynthesis could open up a new horizon in the fields of CO2 utilization.