An investigation of non-noble metal electrodes for carbon dioxide electrolysis in molten lithium carbonate

Abstract

Carbon dioxide (CO2) emissions are a known cause of global warming, but at the same time, they constitute a potentially valuable source of carbon. Using a high-temperature electrolysis process in molten carbonate, CO2 can be transformed into carbon and oxygen. However, the corrosive ambient in molten carbonate necessitates resilient electrode material. To lower the cost, it is also important to select affordable electrodes. This study aimed to investigate the performance of non-noble metal electrodes specifically nickel, stainless steel, and Alloy X (a Ni-Cr-Fe-Mo alloy) in molten lithium carbonate (Li2CO3) at 750∘C. Electrochemical performance was measured using step-wise constant current and cyclic voltammetry, and the yield was examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The investigation revealed that nickel has a lower sum of cathodic and anodic overpotential and OER onset potential than stainless steel and Alloy X. Nickel electrodes produced spherical amorphous carbon; stainless steel electrodes generated amorphous carbon along with nanotubes; and Alloy X electrodes yielded amorphous carbon. The EDS confirmed the formation of carbon with metal contamination from Ni, Fe, and Cr. These results provide insight into the utilization of non-noble metal electrodes for CO2 electrolysis in Li2CO3.