Pyrrolic N-doped carbon catalysts for highly efficient electrocatalytic reduction of CO2 with superior CO selectivity over a wide potential window

Abstract

The electrocatalytic reduction of CO2 to CO is an attractive approach for converting the greenhouse gas to value-added chemicals. However, current catalysts still suffer from low catalytic reactivity and low CO selectivity. Here, we report the synthesis of a series of N-doped carbon catalysts by thermal annealing of the mixture of urea and carbon in argon under varied temperatures, enabling the rational modulation of N species in carbon. The as-prepared NC-650 catalyst with pyrrolic N as the dominant N species can preferentially reduce CO2 to CO with almost 100% CO selectivity over a broad potential range (−0.45 to −1.05 V), coupled with remarkable long-term stability for over 300 h. DFT calculations reveal that the pyrrolic N site is unsaturated (valence state), which favors the formation of the N–COOH unit geometrically and electronically via proton-coupled electron transfer while inhibit hydrogen liberation, resulting in high CO2RR reactivity and CO selectivity of the NC-650 catalyst.