Sustainable Carbons and Fuels: Recent Advances of CO₂ Conversion in Molten Salts

The massive release of the greenhouse gas CO₂ has resulted in numerous environmental issues. In searching for advanced technologies for CO₂ capture/conversions, recent advances in electrochemical reduction of CO₂ in molten salts shed a light on potential solutions to CO₂ mitigation. Electro-reduction of CO₂ in molten salts exhibits features like high selectivity and efficiency towards sustainable carbons and fuels, low toxicity, and possibility to combine with in situ CO₂ capture. In this Minireview, we highlight the tuning of the products in this process and mainly discuss two categories of electrolyte, carbonate-based molten salts (CMS) and those based on halides (HMS). Depending on the synthetic conditions, fuels such as CO or hydrocarbons (in the presence of hydrogen source, i. e., LiOH, NaOH, or KOH in the electrolyte) as well as high-value nanostructured carbons including carbon nanotubes, carbon nanofibers, carbon nano-onions, and graphene can be obtained with high efficiency. The synthesis parameters are compared, and the applications of as-obtained carbons are briefly summarized. Additionally, some perspectives on this technology are also discussed.