Freestanding Bipolar Membranes with an Electrospun Junction for High Current Density Water Splitting

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Bipolar membranes (BPMs) are crucial for electrochemical processes like water splitting.
• Developing efficient and stable BPMs with enhanced water splitting junctions is an ongoing challenge.

Purpose of the Study:

• To fabricate freestanding BPMs with an extended-area water splitting junction using electrospinning.
• To investigate the effect of junction composition, ion-exchange capacity, and catalyst on water splitting performance.

Main Methods:

• Electrospinning of sulfonated poly(ether ether ketone) (SPEEK) and quaternized poly(phenylene oxide) (QPPO) to form a mixed fiber mat.
• Incorporation of water splitting catalyst nanoparticles within the fiber mat.
• Fabrication of a trilayer BPM by sandwiching the junction mat between SPEEK and QPPO films, followed by hot pressing.

Main Results:

• The best performing BPMs utilized a graphene oxide catalyst.
• Achieved a low transmembrane voltage drop of approximately 0.82 V at 1000 mA/cm².
• Demonstrated stable water splitting operation for 60 hours at 800 mA/cm².

Conclusions:

• Electrospun freestanding BPMs with extended-area junctions show promise for efficient water splitting.
• Optimization of catalyst and polymer composition is key to achieving low voltage drops and long-term stability.