2-Chloropyridine grafted on nitrogen-doped carbon nanotubes for efficient electroreduction of CO2 to CO under high overpotentials

Nitrogen-doped carbon nanotubes for CO 2 electroreduction (CO 2 ER) to CO usually perform a low reaction activity due to weak adsorption and high activation energy of CO 2 . Herein, 2-chloropyridine molecules (2-PyCl) as co-catalysts were grafted onto nitrogen-doped carbon nanotubes (NCNT) to prepare a composite electrocatalyst (PyCl-NCNT). The structural characterization and electrochemical tests confirmed that chlorine atoms in 2-PyCl synergized with pyridine molecules, substantially enhancing the CO 2 adsorption capacity, thereby accelerating the CO 2 ER rate. PyCl-NCNT achieved a CO faradaic efficiency (FE CO ) of 91.3% and a CO partial current density (j CO ) of -26.8 mA cm -2 at -1.2 V vs. RHE, maintaining a FE CO above 90% in a wide electrochemical potential window (-0.7 ∼ -1.2 V).