Electronic Modulation and Surface Reconstruction of NiS2 for Enhanced Alkaline Oxygen Evolution Reaction Activity and Durability

Why It Matters

The breakthrough provides a low‑cost, durable OER anode that can replace precious‑metal catalysts in alkaline membrane electrolyzers, accelerating the economics of green‑hydrogen production.

Key Takeaways

• Fe substitution reduces NiS2 band gap by ~0.44 eV, enhancing conductivity
• Alkaline pretreatment creates NiFe (oxy)hydroxide shell, boosting OER activity
• NFS‑15‑AT delivers 1 A cm⁻² at 1.65 V, surpassing IrO₂ benchmark
• Catalyst remains stable >200 h, with suppressed metal leaching and rapid bubble release

Pulse Analysis

Alkaline‑membrane water electrolysis (AEMWE) is emerging as a cost‑effective pathway to green hydrogen, but its commercial viability hinges on non‑noble‑metal oxygen‑evolution catalysts that can survive harsh alkaline conditions. Traditional transition‑metal oxides often degrade quickly, prompting researchers to explore sulfide‑derived frameworks that combine intrinsic conductivity with structural robustness. By introducing iron into the NiS₂ lattice, the team achieved electronic modulation that narrows the band gap, facilitating charge transfer and lowering the kinetic barrier for the key *O → *OOH step, as confirmed by DFT calculations.

The innovative alkaline pretreatment (AT) step converts the Fe‑doped sulfide surface into an amorphous NiFe (oxy)hydroxide layer while preserving the conductive sulfide core. This core‑shell architecture acts as a confined reconstruction zone: the outer shell provides abundant active sites for the OER, improves wettability for rapid bubble detachment, and physically restrains further dissolution of metal ions. Spectroscopic evidence of a higher average Ni oxidation state corroborates the formation of a highly active oxyhydroxide phase, translating to an overpotential of just 286 mV at 10 mA cm⁻².

When deployed in a single‑cell AEMWE, the NFS‑15‑AT/NF anode reaches 1 A cm⁻² at 1.65 V, outpacing commercial IrO₂ under identical conditions and sustaining performance for more than 200 hours without significant leaching. This durability, coupled with the use of earth‑abundant materials, positions the technology as a viable alternative for large‑scale electrolyzer stacks. As the hydrogen economy scales, such advances in catalyst design could lower cap‑ex and op‑ex for green‑hydrogen projects, driving broader adoption across industrial and utility sectors.