Electronic structure regulation of Fe-doped Ni2P nanocrystals towards durable electrocatalytic oxygen evolution

The inherent electrocatalytic potential of transition metal phosphides (TMPs) for oxygen evolution is influenced by the reduced efficiency of electron transfer resulting from the interaction between electronegative phosphorus atoms and transition metals. Here, we introduce Fe into Ni₂P nanocrystals by thermal injection synthesis method, and anchor them on nickel foam (NF) by facile spraying to prepare self-supporting oxygen evolution reaction (OER) electrocatalyst. Promisingly, the optimized electrode of Ni₂P-Fe-2/NF demonstrates low overpotentials of 212 mV with 10 mA·cm⁻² and a 0.9% decay within 300 h test of 50 mA·cm⁻². Notably, when electrode size was expanded to 600 cm² and applied to a larger electrolyzer, its 9 h decay rate at 6 A current was only 1.69%. Characterization results show that Fe doped NiOOH is generated during OER reaction as actual catalyst. Results from density functional theory (DFT) computations suggest that Fe doping shifts NiOOH d-band center to Fermi level, lowering critical *OOH intermediates formation energy barrier during the OER reaction. These findings inform the large-scale industrial application of TMPs as robust electrocatalysts.

Graphical abstract