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.

Most organic commodity chemicals are derived from fossil carbon resources. The dependency is so immense that it is difficult to compensate for the accompanying carbon footprint with current technology and chemical infrastructure. To mitigate the future fossil fuel usage, it is crucial to explore alternative chemical pathways, which are both sustainable and suitable for large-scale productions. Here we demonstrate a closed-loop carbon-neutral chemical route, using standard coin catalyst, to produce high concentrated formate and formic acid. The catalyst’s Faradaic efficiency (FE) of formate is ~ 95.3% with great durability. The chemicals are not only synthesized but also purified and utilized in zero-carbon scenarios. We successfully harvested 45% formate salt and 86.2% formic acid, for applications like anti-freezing reagent and green liquid fuel to power the fuel-cell vehicles.