Carbon-black-supported NiFeP as cost-effective and high-performance OER catalysts for alkaline electrolysis

Green hydrogen production through water electrolysis can help address challenges in renewable energy storage and transportation. However, sluggish kinetics and high overpotentials of the oxygen evolution reaction (OER) restrict the efficiency of large-scale hydrogen generation. This work focuses on the development of a carbon-black-supported nickel-iron phosphide nanoparticle electrocatalyst for OER in an alkaline medium. A cost-efficient and straightforward hydrothermal method, followed by phosphorization, is utilized to prepare nanostructured NiFeP/CB supported by carbon black to enable uniform dispersion and enhance interfacial electron transport. The synthesized catalyst shows a remarkably low overpotential, Tafel slope, and charge transfer resistance. The stability test demonstrates long-term durability, even at higher current densities. Density functional theory (DFT) calculations identify the transition step of ∗[jls-end-space/]-O to ∗[jls-end-space/]-OOH as the rate-determining step. Compared to NiP and FeP, NiFeP exhibits the lowest free energy barrier. Furthermore, total and partial density of states (DOS and PDOS) analysis reveals that NiFeP exhibits a broad and delocalized 3d-band profile, resulting from the synergistic contributions of Ni and Fe. These electronic structure properties, combined with the optimal free energy profiles, are consistent with the excellent OER performance and the experimentally observed activity trend, which shows that NiFeP/CB is better than FeP/CB and NiP/CB.