Graphitic-N highly doped graphene-like carbon: A superior metal-free catalyst for efficient reduction of CO2

Abstract

For metal-free nitrogen(N)-doped carbon catalysts, diverse N-bearing species embedded in the carbon framework are generally regarded as chemical promoters that can upgrade their catalytic performance for CO2 electroreduction reaction (CO2RR). However, it is still a controversy as to which N species plays a dominant role. Herein, a type of large surface area (371 m2/g), N-rich (11.0 wt%) graphene-like carbon electrocatalyst (NG-1000) is fabricated via facile pyrolysis from a precursor composite of dicyandiamide and phthalocyanine. The N-species in the NG-T (T = 700–1000 °C) can be fine-tuned, thus facilitating differentiating functions of the various N-species. Based on the comprehensive analysis of original Pc/CNTs and NG-T catalysts, we identified that the C atoms next to the graphitic-N species in NG-1000 serves as the main active species for CO2RR. In addition, such a non-metal based electrocatalyst is capable of achieving an excellent selectivity of 95.0 % at −0.72 V versus RHE to convert CO2 into CO, with a CO current density of 9.07 mA cm−2, comparable to the state-of-the-art metal-based electrocatalysts.