No abstract

High electrochemical over‐potential and low product selectivity are regarded as the main limitations of electroreduction of CO2. Here, we proposed a new strategy to synthesize metal porphyrin‐hybridized porous and ultra‐thin carbon nanosheets (MPPCN) by the confinement function of the layered template. The layered confinement reaction protects the coordination structure of metal and nitrogen atoms during subsequent high‐temperature treatment while ensuring the formation of ultra‐thin structures. This method effectively prevents the aggregation of metal atoms, so that the metal atoms exhibit a dispersed state of a single atomic level. MPPCN exhibit unexpected catalytic activity for electroreduction of CO2, and the catalytic reaction can be carried out at an over‐potential of 0.39 V. The faradaic efficiency of CO can reach 95.9 % at the potential of −0.7 V versus the reversible hydrogen electrode.

Single-atom metal and nitrogen co-doped carbon catalysts have caused an extensive research boom for electrochemical CO 2 reduction reaction (CO 2 RR). The diversity of metal-N coordination environment at high temperature limits the accurate study of electrocatalytic active sites. In this work, Fe porphyrin is anchored on a nitrogen-doped graphene substrate through the coordination between Fe and N atoms to form atomically dispersed Fe and N co-doped graphene nanosheets. The confinement anchoring effect of the nitrogen-doped graphene substrate prevents Fe atoms from agglomerating into Fe nanoparticles. Apart from that, the different Fe-N coordination environments and their catalytic effects on CO 2 RR are investigated by temperature changes. Electrochemical tests and density functional theory (DFT) calculations indicate that the atomically dispersed saturated Fe-N coordination catalyst have excellent performance for CO2RR and the Faradaic efficiency towards CO can up to 97 % at a potential of À 0.5 V (vs. reversible hydrogen electrode, RHE).