Dynamic self-optimizing reconstruction of Heterostructured FeOOH/Al doped Ni3S2 for efficient anion exchange membrane water electrolysis.

Although the availability of many nickel-based sulfides oxygen evolution reaction (OER) electrocatalysts with excellent intrinsic activity, very few of them perform well in anion exchange membrane water electrolysis (AEMWE). Their poor stability remains the core challenge in large-scale alkaline water electrolysis. In this work, the use of amorphous FeOOH nanoparticles is proposed as a modifier of Al doped Ni3S2 (FeOOH/NiAlS) to develop robust OER electrode suitable for AEMWE. Under operation conditions, FeOOH protect the bulk sulfides from further corrosion, in turn effectively improves the catalyst utilization due to highly conductive property. Meanwhile, surface reconstructed Al-NiFeOOH serves as the actual active phase, monitored by in situ Raman and EIS. Density functional theory (DFT) reveals that Fe doping optimize their adsorption property, elongates the NiO bond, and act as a new active site to augment OER activity. Specifically, the reconstructed FeOOH/NiAlS shows an ultra-low overpotential of 316 mV at 1 A cm-2 and high stability at 0.5 A cm-2 over 400 h. The corresponding AEMWE requires a cell voltage of only 1.72 V to reach 1 A cm-2, while maintaining stable operation for 1400 h at 0.5 A cm-2, providing a promising prospect for practical applications.