Nano-polyaniline enables highly efficient electrocatalytic reduction of CO2 to methanol in supporting electrolyte-free media and the detection of free-radical signals

Abstract

Metals and metal oxides are widely used as catalysts for the electrochemical reduction of CO₂. Here, we report a low-cost catalyst based on nano-polyaniline polymerized on graphite for the electrochemical reduction of CO₂ in CO₂-saturated water free of supporting electrolytes. The nano-polyaniline electrode in this solution shows low resistance and low charge-transfer impedance (R_ct), which leads to a rather high reduction current density (−16.8 mA cm⁻²) and low overpotential (−0.44 V vs. Ag/AgCl). This solution is environment-friendly and mimics that in photosynthesis. The free radical signal of CO₂ was successfully detected during the reduction process. The ¹H NMR result demonstrates that the only product formed was methanol.