Graphene oxide prompted double-crosslinked Poly(vinyl alcohol)/Poly(diallyldimethylammonium chloride) Anion-exchange membrane for superior CO2 electrochemical reduction

Electrochemical CO2 reduction reaction is a promising way to mitigate the greenhouse effect and convert CO2 into high value-added fuels and chemicals. However, perusing of ion-conducting membrane for maximizing the performance of a CO2 electrolyzer is still a big challenge. Here, we report an anion-exchange membrane based on polymer composites of poly(vinyl alcohol) (PVA) and poly(-diallyldimethylammonium chloride) (PDDA) for use in CO2 electrolysis. Specifically, graphene oxide (GO), as a promoter, was introduced to improve the efficiency, selectivity and stability of CO2 electroreduction system. Coupled with double-crosslinking strategy, the PVA/[email protected]– membrane enables a high conductivity of 43.46 mS cm−1 at room temperature with largely inhibited water uptake. As a result, the membrane with 2 wt% GO exhibits considerable current density (30 mA cm−2), high faraday efficiency (90%) and good stability at the optimal potential of −0.96 V vs RHE, which is superior to commercial anion-exchange membrane A201 and cation-exchange membrane Nafion 117 (Faraday efficiency is 80% and 58%, respectively). The improved efficiency of hydroxide-conductive membrane is attributed to GO microregulation of 3D inner-porous structure of the membrane, which can provide more sites and long-range continuous channels for OH– transport, thus efficiently improves the “trade-off” between hydroxide conductivity/mechanical property and the water absorption behavior.