Conductive N, S doped Copolymers as Stable Metal-Free Electrocatalysts for Water Splitting

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Noble metal and metal oxide electrocatalysts (e.g., Pt, IrO2, RuO2) are standard for alkaline water splitting but are expensive, unstable, and environmentally impactful.
• Developing cost-effective and sustainable alternatives is crucial for efficient hydrogen production.

Purpose of the Study:

• To synthesize and evaluate novel metal-free conducting polypyrrole-polythiophene (Ppy-Ptp) copolymer and polypyrrole (Ppy) materials as electrocatalysts for water splitting.
• To assess their performance in oxygen evolution reaction (OER) and hydrogen evolution reaction (HER).

Main Methods:

• Synthesis of Ppy-Ptp copolymer and Ppy materials.
• Deposition of catalysts onto nickel foam (NF) substrates.
• Electrochemical characterization of OER and HER activity, including overpotential measurements.
• Assembly and testing of an alkaline anion-exchange membrane (AEM) electrolyzer.

Main Results:

• The optimal Ppy-Ptp (1:3) catalyst on NF demonstrated superior OER performance (250 mV overpotential at 20 mAcm⁻²) compared to benchmark IrO2/NF (290 mV).
• The Ppy/NF catalyst showed excellent HER performance (72 mV overpotential at 10 mAcm⁻²).
• An electrolyzer using Ppy-Ptp and Ppy achieved lower operating potentials (1.55 V at 10 mAcm⁻²) and demonstrated stability over 50 hours.

Conclusions:

• Metal-free Ppy-Ptp and Ppy electrocatalysts are highly effective for alkaline water splitting.
• These polymer-based materials offer a promising, sustainable alternative to noble metal catalysts for industrial-scale hydrogen synthesis.