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

Nitrogen-doped carbon nanotubes (NCNT) for CO2 electroreduction (CO2ER) to CO usually perform a low reaction activity due to weak adsorption and high activation energy of CO2. Herein, 2-chloropyridine molecules (2-PyCl) as co-catalysts were grafted onto 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 CO2 adsorption capacity, thereby accelerating the CO2ER rate. PyCl-NCNT achieved a CO faradaic efficiency (FECO) of 91.3 % and a CO partial current density (jCO) of −26.8 mA cm−2 at −1.2 V vs. RHE, maintaining a FECO above 90 % in a wide electrochemical potential window (−0.7 ∼ −1.2 V).