Hot-pressed, mechanically stable bipolar membranes for water electrolysis and CO2 reduction
- 1University of Liverpool
- 2Keele University
Abstract
Bipolar membranes (BPM), composed of a cation exchange layer and an anion exchange layer, can enable steady-state operation at different pHs at the cathode and anode in electrolyzers. This enables the independent optimization of the cathode and anode catalysts for acidic and alkaline environments, respectively, which increases the scope for low-cost materials. Commercially available BPMs are operational only in a limited current range, therefore we aimed to develop custom BPMs for higher currents that are easily fabricated, mechanically stable, and suitable for storage in dry form. We used commercial single membranes combined with TiO 2 as the water dissociation catalyst in the junction, and have developed a hot-pressing method to prepare self-standing membranes that are mechanically robust, without a loss in electrochemical performance. Electrochemical Impedance Spectroscopy (EIS) was used to deconvolute the water dissociation resistance from other processes, leading to better understanding of the parameters that determine BPM performance. We demonstrate that the higher-performance BPMs surpass commercial BPMs for use in water electrolyzers, primarily due to a large decrease in the water dissociation overpotential to < 400 mV at 0.5 A cm -2 at 60 °C compared to ~1.3 V for the benchmark material. We also show how the membranes can be employed for high current density CO 2 electrolysis in a device structure that enable high CO 2 utilization efficiency, with the hot-pressed membranes achieving lower cell voltage and higher CO Faradaic efficiency compared to our previous reports with a custom BPM.
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BibTeX
@misc{siritanaratkul2026hotpressed,
title = {{Hot-pressed, mechanically stable bipolar membranes for water electrolysis and CO2 reduction}},
author = {Bhavin Siritanaratkul and Dora Alicia Garcia-Osorio and Veronica Hanna and Alexander Cowan},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv-2025-c9n8r/v2},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv-2025-c9n8r/v2},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Hot-pressed, mechanically stable bipolar membranes for water electrolysis and CO2 reduction
AU - Bhavin Siritanaratkul
AU - Dora Alicia Garcia-Osorio
AU - Veronica Hanna
AU - Alexander Cowan
PY - 2026
DA - 2026/09/10
PB - ChemRxiv
DO - 10.26434/chemrxiv-2025-c9n8r/v2
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv-2025-c9n8r/v2
AB - Bipolar membranes (BPM), composed of a cation exchange layer and an anion exchange layer, can enable steady-state operation at different pHs at the cathode and anode in electrolyzers. This enables the independent optimization of the cathode and anode catalysts for acidic and alkaline environments, respectively, which increases the scope for low-cost materials. Commercially available BPMs are operational only in a limited current range, therefore we aimed to develop custom BPMs for higher currents that are easily fabricated, mechanically stable, and suitable for storage in dry form. We used commercial single membranes combined with TiO 2 as the water dissociation catalyst in the junction, and have developed a hot-pressing method to prepare self-standing membranes that are mechanically robust, without a loss in electrochemical performance. Electrochemical Impedance Spectroscopy (EIS) was used to deconvolute the water dissociation resistance from other processes, leading to better understanding of the parameters that determine BPM performance. We demonstrate that the higher-performance BPMs surpass commercial BPMs for use in water electrolyzers, primarily due to a large decrease in the water dissociation overpotential to < 400 mV at 0.5 A cm -2 at 60 °C compared to ~1.3 V for the benchmark material. We also show how the membranes can be employed for high current density CO 2 electrolysis in a device structure that enable high CO 2 utilization efficiency, with the hot-pressed membranes achieving lower cell voltage and higher CO Faradaic efficiency compared to our previous reports with a custom BPM.
ER -