High-Performing Anion Exchange Membrane Water Electrolysis Using Self-Supported Metal Phosphide Anode Catalysts and an Ether-Free Aromatic Polyelectrolyte

Anion exchange membrane water electrolysis (AEMWE) is going through a critical transition phase from the laboratory scale to scale-up prospects owing to the development of highly durable ether-free aromatic anion exchange membranes. The next important step is processing competent nonprecious metal catalysts as scalable electrodes. Here, we fabricated an iron-integrated self-supported nickel phosphide (Ni2P–Fe/NF) catalyst for the sluggish oxygen evolution reaction (OER). It was demonstrated that this catalyst could work as a high-performing anode electrode in an AEMWE system when combined with a durable ether-free aromatic polyelectrolyte. The noble metal-free Ni2P–Fe/NF electrode, developed employing a simple and scalable strategy demonstrated higher performance as an anode electrode in water electrolysis with a cell voltage of 1.73 V for 1 A/cm2 with an excellent energy conversion efficiency (86%) in 1 M KOH and the MEA is also found to be stable for 24 h at 200 mA/cm2. Electrochemical and spectroscopic investigations over the Ni2P–Fe/NF metal electrode surface during and post-OER disclosed the beneficial synergistic interaction of the metal species, leading to lattice alterations, formation of oxy-hydroxide active species, and improved electron charge transfer as crucial factors responsible for the excellent performance and stability. This work involves scalable processing of catalyst structures over a nickel foam surface, insights into the thickness variation of the substrate for catalyst processing, and identifying the OER characteristics under water electrolysis conditions, which are significant in the application direction of applying noble metal-free electrodes for green hydrogen generation in AEMWE.