Bifunctional Nitrogen and Cobalt Codoped Hollow Carbon for Electrochemical Syngas Production.

Abstract

Electrochemical conversion of CO2 and H2O into syngas is an attractive route to utilize green electricity. A competitive system economy demands development of cost‐effective electrocatalyst with dual active sites for CO2 reduction reaction (CO2RR) and hydrogen evolution reaction (HER). Here, a single atom electrocatalyst derived from a metal–organic framework is proposed, in which Co single atoms and N functional groups function as atomic CO2RR and HER active sites, respectively. The synthesis method is based on pyrolysis of ZnO@ZIF (zeolitic imidazolate framework). The excess in situ Zn evaporation effectively prevents Co single atoms (≈3.4 wt%) from aggregation and maintains appropriate Co/N ratio. The as‐prepared electrocatalyst is featured with high graphitic degree of carbon support for rapid electron transport and sponge‐like thin carbon shells with hierarchical pore system for facilitating active site exposure and mass transport. Therefore, the electrocatalyst exhibits a nearly 100% Faradic efficiency and a high formation rate of ≈425 mmol g−1 h−1 at 1.0 V with the gaseous product ratio (CO/H2) approximating ideal 1/2. With the assistance of an extensive material characterization and density functional theory (DFT) calculations, it is identified that Co single atoms are uniformly coordinated in the form of Co–C2N2 moieties, and act as the major catalytic sites for CO2 reduction.