Electrografting amines onto silver nanoparticle-modified electrodes for electroreduction of CO2 at low overpotential

Abstract

Reducing carbon dioxide (CO₂) to value-added synthons in a selective and efficient manner remains a sizable challenge to CO₂ conversion research. Although many electrocatalysts have been reported to date, those with both high selectivity and high activity have continued to elude us. In this project, successful electroreduction of CO₂ to carbon monoxide (CO) and formate was achieved at low overpotential through a facile and green one-step immobilization of p-phenylenediamine (PPD) onto a bare glassy carbon electrode (GCE) and a silver nanoparticle modified GCE surface (AgNPs/GCE). The faradaic efficiency (FE) and current density (j) of PPD were significantly improved from FE: 17% and j: −0.86 mA cm⁻² to FE: 91% and j: −6.5 mA cm⁻² after immobilizing PPD onto the AgNPs/GCE electrode support. The PPD–AgNPs/GCE system was observed to suppress the hydrogen evolution reaction and reduce CO₂ to CO and formate with 4-fold more positive potentials (−0.2 V vs. RHE) in an alkaline environment. This work provides an effective strategy for the improvement of electrocatalytic performance which could inspire the future design of heterogeneous molecular catalysts for CO₂ conversion and shines more light on the potential of electrografting onto a variety of electrode surfaces.