Interstitial Manganese-Tuned Nickel-Iron Diselenide Anode for Efficient and Durable Anion Exchange Membrane Water Electrolysis

Anion exchange membrane water electrolysis (AEMWE) employing Ir/Ru-free anodes emerges as a bright prospect for green hydrogen society. Here, a Ni0.8Fe0.2Mn0.1Se2 nanosheet electrocatalyst is reported, in situ grown on stainless-steel paper, as an efficient and durable self-supporting AEMWE anode for oxygen evolution reaction (OER). The interstitial [MnSe4] tetrahedra elevate the Fermi level and narrows the band gap of the electrocatalyst, thereby expediting electrode reaction kinetics and increasing the electrical conductivity. In addition, the interstitial Mn atoms attenuate the electron density of Ni and Fe and motivate phase transition to actual active (Mn, Fe)-doped gamma-NiOOH species. The downward d-band center of Ni active center facilitates the rate-limiting *OOH desorption step, refreshing the active center, and reducing the free energy barriers for OER. Accordingly, the Ni0.8Fe0.2Mn0.1Se2 electrode achieves OER overpotentials of 149 and 232 mV at 10 and 100 mA cm-2 in 1 m KOH. The AEMWE cell incorporating Ni0.8Fe0.2Mn0.1Se2 anode demonstrates high performance (1.0 A cm-2 at 1.68 Vcell) and durability (at 1 A cm-2 for 300 h), surpassing most AEMWE cells that use NiFe-based anodes. This work highlights the potential of noble-metal-free anodes for efficient and durable AEMWE.