High-purity and high-concentration liquid fuels through CO2 electroreduction

Liquid fuels generated from the electrochemical CO2 reduction reaction (CO2RR) are of particular interest due to their high energy densities and ease of storage and distribution. Unfortunately, they are typically formed in low concentrations and mixed with impurities due to the current limitations of traditional CO2 electrolysers as well as CO2RR catalysts. In this Perspective, we emphasize that while the declining renewable electricity price can greatly lower the formation cost of liquid fuels, the downstream purification process will add an extra layer of cost that greatly harms their economic feasibility for large-scale applications. Different strategies in reactor engineering and catalyst improvement are proposed to realize the direct and continuous generation of high-purity and high-concentration liquid fuels from CO2RR electrolysers, allowing this electrochemical route to become more competitive compared with the traditional chemical engineering industry in the future. Liquid fuels produced by electrocatalytic CO2 reduction are costly to separate from liquid electrolytes in a conventional cell. This Perspective identifies the need for novel cell designs that can directly produce high-concentration and high-purity products and discusses the progress towards this goal using porous solid electrolytes.