Diaphragm-based carbon monoxide electrolyzers for multicarbon production under alkaline conditions

Transforming waste carbon into valuable fuels and chemicals is a key step toward sustainable manufacturing. One promising approach is the electrochemical conversion of carbon monoxide (CO), a product of CO₂ recycling, into energy-rich multicarbon (C₂₊) compounds. However, current CO electrolyzers rely on anion exchange membranes (AEMs) that degrade over time when exposed to organic intermediates, limiting their practical use. Here we show that low-cost diaphragm materials, such as Zirfon, can serve as robust alternatives to AEMs in alkaline CO electrolysis. We evaluate a range of diaphragms and identify candidates that match or exceed the performance of commercial AEMs across a wide range of operating conditions (50 to 400 mA cm^-2). At 60 °C, Zirfon-based cells maintain 45% Faradaic efficiencies for acetate over 250 hours, while state-of-the-art AEMs fail within 150 hours. Moreover, a 100 cm² Zirfon cell operates stably for 700 hours at 200 mA cm^-2. These findings demonstrate that diaphragms offer a scalable and durable pathway for CO electrolysis, helping reduce system costs and enhance compatibility with renewable energy inputs.