- Lucas, Éowyn;
- Bui, Justin C;
- Stovall, Timothy Nathan;
- Hwang, Monica;
- Wang, Kaiwen;
- Dunn, Emily R;
- Spickermann, Ellis;
- Shiau, Lily;
- Kusoglu, Ahmet;
- Weber, Adam Z;
- Bell, Alexis T;
- Ardo, Shane;
- Atwater, Harry A;
- Xiang, Chengxiang
Bipolar membranes (BPMs) enable isolated acidic/alkaline regions in electrochemical devices, facilitating optimized environments for electrochemical separations and catalysis. For economic viability, BPMs must attain stable, high current density operation with low overpotentials in a freestanding configuration. We report an asymmetric, graphene oxide (GrOx)-catalyzed BPM capable of freestanding electrodialysis operation at 1 A cm-2 with overpotentials <250 mV. Use of a thin anion-exchange layer improves water transport while maintaining near unity Faradaic efficiency for acid and base generation. Voltage stability exceeding 1100 h with an average drift of 70 μV/h at 80 mA cm-2 and 100 h with an average drift of −300 μV/h at 500 mA cm-2 and implementation in an electrodialysis stack demonstrate real-world applicability. Continuum modeling reveals that water dissociation in GrOx BPMs is both catalyzed and electric-field enhanced, where low pKa moieties on GrOx enhance local electric fields and high pKa moieties serve as active sites for surface-catalyzed water dissociation. These results establish commercially viable BPM electrodialysis and provide fundamental insight to advance design of next-generation devices.