Controlled assembly of nitrogen-doped iron carbide nanoparticles on reduced graphene oxide for electrochemical reduction of carbon dioxide to syngas

Abstract

The electrocatalytic CO2 reduction reaction (CO2RR) decreases the amount of greenhouse gas in the atmosphere while enabling a closed carbon cycle. Herein, iron oleate was used as a precursor to produce oleic acid-coated triiron tetraoxide nanoparticles (Fe3O4@OA NPs) by pyrolysis, which was then assembled with reduced graphene oxide (rGO) and doped with dicyandiamide as a nitrogen source to obtain nitrogen-doped iron carbide nanoparticles assembled on rGO (N-Fe3C/rGO NPs). The catalyst prepared by nitrogen doping at 800 °C with an Fe3O4@OA NPs to rGO weight ratio of 20:1 showed good activity and stability for the CO2RR. At −0.3 to −0.4 V, the H2/CO ratio of the product from the catalyzed CO2RR was close to 2; thus, the product can be used for Fischer-Tropsch synthesis. The results of a series of experiments and X-ray photoelectron spectroscopy analysis showed that the synergy between the CN and FeN groups in the catalyst can promote the reduction of CO2 to CO. This work demonstrates a facile method for improving the catalytic reduction of CO2.