A highly efficient and durable self-standing iron-cobalt-nickel trimetallic phosphide electrode for oxygen evolution reaction

The development of cost-effective, highly efficient, and durable oxygen evolution reaction (OER) electrocatalysts is both a necessity and challenge for large-scale water electrolyzers, which is crucial for future sustainable and clean energy systems. Here we report a self-standing trimetallic phosphide (FeCoNi-P/NF) electrode prepared by the electroreduction of Fe2O3 and Co3O4 on the Ni foam in molten salts and the subsequent phosphorization process. In the electroreduction process, the Ni source provided by Ni foam participates in the alloying process as a solvent phase, which leads to the strong bonding between the substrate and the active material. In addition, the alloys grown by co-reduction and alloying on the three-dimensional skeleton of the Ni foam can expose more active sites by increasing the surface areas through the phosphorization process. Benefiting from the synergistic effects and strong electronic coupling from the Fe, Co, and Ni trinary phosphides, the FeCoNi-P/NF shows excellent OER activity and stability with an overpotential of only 239.5 mV at 10 mA cm−2 and a long-term stability of more than 200 h at 50–300 mA cm−2 in 1.0 M KOH. Overall, this paper offers a straightforward method to prepare low-cost and durable muti-component transition metal-based self-standing OER electrodes.