A Novel Cyclized Polyacrylonitrile Binder Strategy for Efficient Oxygen Evolution Reaction Catalysts

Area of Science:

• Materials Science
• Electrochemistry
• Chemical Engineering

Background:

• Conventional polymer binders like Nafion exhibit limitations in hydroxide conductivity and interfacial properties for alkaline water electrolysis.
• Developing advanced binders is crucial for improving the efficiency of oxygen evolution reactions (OER).

Purpose of the Study:

• To introduce a thermally cyclized polyacrylonitrile (CPAN) binder system with a conjugated ladder structure for alkaline water electrolysis.
• To investigate the impact of CPAN binders on electrode performance and understand the underlying mechanisms.

Main Methods:

• CPAN binders were synthesized via controlled thermal treatment at various temperatures.
• Electrode performance was evaluated using electrochemical techniques, including overpotential and Tafel slope measurements.
• Electrode structural and chemical properties were characterized to correlate with performance.

Main Results:

• CPAN-400 demonstrated optimal pyridinic N content and provided π-conjugated pathways, leading to enhanced electronic conductivity and hierarchically porous architectures.
• The NiFe/CPAN-400 electrode achieved significantly lower overpotentials for OER compared to NiFe-Nafion and NiFe-PAN electrodes.
• Synergistic effects, including increased electrochemically active surface area, improved wettability, and optimized charge transfer, contributed to enhanced performance.

Conclusions:

• Thermally induced polymer cyclization is a versatile strategy for developing advanced binders for alkaline water electrolysis.
• The pyridinic nitrogen-enriched CPAN binder facilitates a transition in the rate-determining step, improving OER kinetics.
• CPAN binders offer a promising alternative to conventional binders for efficient and durable electrochemical applications.