Proton antagonist membrane towards exclusive CO₂ reduction

Membrane electrode assembly reactor offers great promise toward practical CO₂ electrolysis. Unfortunately, traditional proton exchange membrane possesses strong acidic chemical environment, which facilitates undesired hydrogen evolution reaction. Here we report a proton antagonist strategy, through which the proton diffusion pathways have been severely impeded by Na⁺ cation to produce an alkaline-rich environment. With this new membrane electrode assembly, we can significantly suppress the hydrogen evolution and achieve a Faradaic efficiency of 95.7% for CO with 51.5% energy efficiency. In addition, our proton antagonist membrane outperforms the commercial anion exchange membrane in both conductivity and oxidation resistance lifetime, which are crucial for large scale electrolysis of carbon neutral chemicals.