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

Abstract

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.