Electrochemical reduction of gaseous CO2 with a catechol and polyethyleneimine co-deposited polypropylene membrane

•A polypropylene membrane based solid electrolyte was developed for CO2 reduction.•The membrane was developed by deposition of bio-inspired polyphenolic coatings.•High CO production rate and the Faradaic efficiency were achieved.•The novel composite SPE may have great potential in industrial application.

A novel solid polymer electrolyte was developed by co-deposition of catechol (CCh) and polyethyleneimine (PEI) on a polypropylene membrane for electrochemical reduction of CO2 (ERC) in gas phase. ERC performance was both investigated in a gas-gas mode and a gas-liquid mode. The maximum CO production rate was 121 μmol/h and the faradaic efficiency was 51% in the gas-liquid mode, which were much higher than those obtained with AM-7001 under the same condition. The high loading rate of quaternary ammonium ions on the membrane and the large surface area provided by the porous nano-structure of the membrane contribute to the high ERC efficiency. Furthermore, the cost of the CCh/PEI-Q membrane was much lower than commercial Nafion membranes, endowing this novel composite SPE with great potential in industrial application.