Boosting electrocatalytic CO2 reduction over Ni/CN catalysts derived from metal-triazolate-framework by doping with chlorine

Abstract

The CO2 electrochemistry reduction (CO2ER) to valuable chemicals is one of the attractive strategies for the utilization of greenhouse gas and carbon recovery. The catalyst for the reaction is extremely important. In the present work, a carbon matrix derived from the pyrolysis of nitrogen-rich metal triazole (MET) supported Ni-metal (denoted as Ni/CN) was developed as a catalyst for the CO2ER. A catalyst with a heteroatom chlorine introduction, named the Ni/(Cl-CN), enhanced the catalytic performances remarkably. The Ni/(Cl-CN) catalyst with the Ni loading of 4.5 wt% showed the best catalytic performance with a Faradaic efficiency of CO (FECO) over 90% in a range of −0.7 to −1.1 V (vs. RHE) in 0.1 M KCl solution, and the highest formation activity reached 137.1 mmol∙gcat−1·h−1. Besides, the highest total current density reached 21.4 mA cm−2 (FECO>90%) in an H-type cell at −1.1 V (vs. RHE). The catalyst was characterized by diverse technologies, and the results indicated that it contains Ni NPs and homogenous dispersed Ni sites, and both of them are active for the reaction. The introduction of Cl atom indeed promotes the catalytic performance probably via the stabilization of Ni+ species and enhances the CO2 adsorption and activation. The present work not only provides an efficient heteroatom-doped metal-NC catalyst in CO2ER to CO but also sheds light on tuning catalytic performances by doping halogen atoms.