When amine-based conducting polymers meet Au nanoparticles: suppressing H2 evolution and promoting the selective electroreduction of CO2 to CO at low overpotentials

Abstract

The electrochemical reduction of CO₂ is a promising method to produce reusable carbon forms from renewable resources. Herein, we propose a facile strategy for improving CO selectivity by designing an amine-based conducting polymer for supporting Au nanoparticles (Au/PANI) that is then used as an electrocatalyst for the electrochemical CO₂ reduction reaction. The oxidized quinonoid imine (QI) units and reduced benzenoid amine (BA) units in polyaniline (PANI) offer a possible approach for combining with metal ions. The size and distribution of Au NPs on PANI can be controlled by adjusting the concentration of Au ions. Au/PANI prepared with 1.0 mM Au ions shows a maximum CO faradaic efficiency (FE_CO) of 90.32% at −0.7 V vs. RHE when compared with Au NPs coupled with PANI-derived N-doped carbon nanofibers (Au/NCNFs) (FE_CO of 33.85% at −0.7 V vs. RHE); this result suggests that PANI plays a significant role in improving CO selectivity. Moreover, Raman spectroscopy and the temperature programmed desorption of CO₂ (CO₂-TPD) indicate that the N–H groups of PANI can catch CO₂ and suppress H₂ evolution.