Constructing single-atomic nickel sites in carbon nanotubes for efficient CO2 electroreduction

Electrochemical CO2 reduction (ECR) has been considered as the most promising route to convert CO2 into fuels, but suffers inferior conversion efficiency and product selectivity due to the lack of effective electrocatalysts. Herein, the N-coordinated single-atomic Ni active sites embedded in porous carbon nanotubes (Ni/N-CNTs) are constructed through one-pot pyrolysis strategy as an efficient ECR electrocatalyst. The Zn source in pyrolysis plays a key role in the formation of bamboo-like CNTs, and increased concentrations of surface defects and single-atomic Ni sites of the electrocatalyst. All these benefits endow the electrocatalyst with excellent ECR performance, achieving a large CO Faradaic efficiency (FECO) up to 98% and turnover frequency up to 304.5 h−1 at a relatively low potential of −0.65 V vs. RHE. Furthermore, over 80% FECO can be maintained in a wide potential range from −0.57 to −0.81 V. In addition, the electrocatalyst also shows high operation stability for 20 h without obvious FECO and jCO decay. We believe this study will shed a new light on the design of highly efficient M/N–C catalyst for ECR systems.