Construction of Ni/N Co-doped Self-supported Carbon Foam Electrodes for Electrocatalytic CO2 Reduction

A series of nickel/nitrogen co-doped self-supported carbon foam electrodes were prepared by impregnation, curing and carbonization using asphalt as the carbon source and polyurethane foam as the template, and then characterized by scanning electron microscopy, transmission electron microscopy, N-2 adsorption-desorption analysis, Raman spectroscopy and X-ray photoelectron spectroscopy. The results show that the prepared carbon foam electrodes possess a three-dimensional macroporous skeleton structure. Moreover, their surface is abundant in defect sites and Ni-N coordination structures. The content of N species can be regulated by varying the carbonization temperature, thereby enabling the regulation of the content of Ni-N-x active sites. The carbon foam electrodes were directly used as a self-supported electrode for the electroreduction of CO2, and a syngas with a stable and controllable H-2/CO molar ratio could be obtained. The H-2/CO molar ratio can be tuned from 1/2 to 2/1 within the potential window of -0.9 similar to-1.3 V(vs. RHE). In addition, the current density of the carbon foam electrode obtained at the carbonization temperature of 900 degrees C can be maintained at 5.7 mA/cm(2) after a sustained reaction for 10 h, and the H-2/CO molar ratio can be maintained at about 1/1.