A new scientific publication from the Membrane Materials & Processes group at Eindhoven University of Technology (TU/e), a key scientific partner in the DRIVE project, presents a breakthrough in the field of bipolar membranes (BPMs). Published in the Journal of Materials Chemistry A, the study “Manipulating interlayer morphology in electrospun bipolar membranes: A key to overcome the trade-off between perm-selectivity and resistance” (Wang et al., 2025) demonstrates, for the first time, a viable pathway to simultaneously achieve low membrane resistance and high perm-selectivity.
Traditionally, BPMs suffer from a fundamental performance trade-off:
- Thinner membranes offer low resistance but lose selectivity.
- Thicker membranes maintain selectivity but introduce high resistance, limiting efficiency and scalability.
This new research disrupts that paradigm.
What the Study Achieves
1. A novel catalytic layer based on a phytic acid–Fe³⁺ complex
The research introduces, for the first time, a phytic acid and Fe³⁺ complex as a catalyst for water dissociation. Using a Layer-by-Layer method, the catalyst was embedded within the interfacial layer (IL), significantly boosting water dissociation efficiency and improving perm-selectivity at the same time .
2. Precision control of membrane thickness using electrospinning
By adjusting the number of electrospun mats in each layer – cation exchange layer (CEL), IL, and anion exchange layer (AEL) – the fabricated BPMs exhibit finely tuned thicknesses ranging from 40 to 90 μm. Notably, both conductivity and perm-selectivity of the BPMs improved as the membranes became thinner, contradicting conventional trade-off barrier between resistance and perm-selectivity.
3. Revealing the real mechanism behind improved performance
The work shows that performance is governed not simply by membrane thickness, but by the degree of interpenetration between the layers during hot-pressing.
The key finding:
Penetration of the AEL into the catalytic IL improves selectivity and reduces resistance.
This enhanced interlayer morphology creates more effective catalytic area and suppresses unwanted proton crossover.
4. A new generation of high-performance BPMs
Based on these insights, the researchers developed an ultra-thin BPM composed of just:
- 1 catalytic IL, and
- 1 AEL,
without the need for a CEL.
This BPM achieved:
- 1.0 V at 100 mA/cm²,
- 95% perm-selectivity,
- and performance comparable to commercial BPMs — but with superior selectivity and reduced water transport limitations.
Why This Matters for DRIVE
This innovation directly supports the DRIVE project’s mission to develop next-generation CO₂ capture and regeneration technologies. Improved BPMs unlock:
- Higher energy efficiency of organic acid and base regeneration in Zero-Emissions Ultra-Stripping (ZEUS) technique
- Lower operational costs, thanks to reduced resistance and improved ion management
- Optimized water management at high current densities — critical for industrial scalability
The electrospun BPM design demonstrated in this study provides a blueprint for producing membranes that are more conductive and selective, aligning perfectly with DRIVE’s objectives for the deep removal of CO₂.
Full Paper Access
The full open-access article is available through the Royal Society of Chemistry:
DOI: 10.1039/D5TA08242K