Abstract: In the electrochemical carbon dioxide reduction reaction (ECO₂RR), catalytic materials face a series of challenges such as susceptibility to poisoning under complex practical application conditions. In this study, commercial multi-walled carbon nanotubes were used to prepare defect rich in graphitic carbon materials through nitrogen doping and removal methods. The morphology, crystal structure, elemental composition, and defect degree of the catalysts were analyzed and characterized by transmission electron microscopy (TEM), aberration-corrected scanning transmission electron microscopy (AC STEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectrometer. Based on the flow cell testing system, the results showed that the activity of defective carbon nanotubes is much higher than that of untreated carbon nanotubes, and the catalytic performance improved with the increase of defect degree. Among them, MWCNT-N-800 with the highest defect degree can achieve excellent electrochemical activity for carbon dioxide reduction to carbon monoxide over a broad potential range, with a maximum carbon monoxide Faraday efficiency of more than 99% and a current density of more than 200 mA cm-2. Furthermore, under the simulated flue gas conditions containing poisoning substances, the Faradaic efficiency of carbon monoxide for MWCNT-N-800 still remained above 96%, showing good poisoning resistance. This study provides ideas for the development of efficient and poison-resistant non-metallic ECO2RR catalysts.

Key words: Carbon dioxide reduction; Electrocatalysis, Carbon defects, Commercial carbon nanotubes, Poison-resistant