Copper and cobalt loading carbon as an efficient catalyst for the electroreduction CO2 to CO and hydrocarbons

Electrocatalytic reduction of carbon dioxide to syngas and hydrocarbons is a promising way to reduce CO2 emissions. In this work, Cu2+ was introduced into the synthesis process of ZIF-67, and a series of CoCu-N-C composites were synthesized by adjusting the molar ratio of Co/Cu and calcination temperature. X-Ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) tests showed that the metal mainly loaded on the carbon matrix in the form of metallic Co/Cu, and a part metal was doped into the carbon matrix in the form of MN. Transmission Electron Microscopy (TEM) showed that the metallic Co/Cu uniformly distributed on the carbon matrix because of the wrapping by carbon matrix. Linear Sweep Voltammetry (LSV) test displayed that CoCu-N-C composites exhibited higher electrocatalytic activity than Co-N-C for CO2 reduction. The Faradic efficiency (FE %) of CH4, CO and H-2 of CoCu(1:3)-N-C-900 at-0.53 V(vs. RHE) was 21%, 35% and 30%, respectively. Then the effect of Co/Cu, calcination temperature and reduction potential on the FE% of CH4, CO and H(2 )was investigated. A wider range of CO/H2 ratio from 0.29 to 1.17 can be obtained by adjusting Co/Cu. Mechanism was explored through the acid etching experiments, KSCN solution dipping and XPS spectra analysis. Results indicated that the introduction of metallic Cu greatly promoted the shift of electron in CoCu(1:3)-N-C-900 and its adsorption capacity towards CO2, ultimately improving its electrocatalytic activity. This work provided a refined paradigm for designing earth-abundant electrocatalysts used to effectively catalytic CO2 to CO and hydrocarbons.