Catalysis performance comparison for electrochemical reduction of CO2 on Pd–Cu/graphene catalyst†
Abstract
A Pd–Cu/graphene catalyst for the electrochemical reduction of CO2 was prepared by means of sodium borohydride reduction in a graphite oxide suspension with metal precursor salts, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), linear sweep voltammetry (LSV), cyclic voltammetry (CV), and current–time (I–t) scans technologies. The formation of Pd–Cu catalysts was investigated by changing the precursors and the Pd–Cu ratio. The results indicated that graphene with a d-spacing of 3.82 Å was fabricated and Pd–Cu metal nanoparticles whose size ranges from 8 to 10 nm were highly dispersed on the graphene sheets with amorphous structure. Additionally, sharp increase of the reduction current under CO2 compared to that under N2 could be observed which contributed to the catalytic reaction of CO2 reduction on the Pd–Cu/graphene electrode. The best catalytic performance of the metal/graphene catalysts was achieved on 1 wt% Pd–2 wt% Cu/graphene, which had a relative positive peak potential and reduction current were −1.3 V (vs. Ag/AgCl) and −2.8 mA, respectively. The Pd–Cu/graphene electrode effectively suppressed the reaction process of hydrogen and showed stable CO2 reduction activity. Finally, the reaction pathway for the CO2 reduction on the Pd–Cu/graphene electrode was proposed.