Fe-doped promotes phosphorization and dispersibility of Ni catalysts for efficient and stable HER and OER

Abstract

Developing efficient, stable, and cost-effective catalysts is crucial for hydrogen production through electrolysis of water. In this study, a comprehensive work was conducted on the electrocatalytic hydrogen and oxygen evolution performance of nickel-based phosphides doped with metallic iron. The Ni5P4/Ni2P/Fe2P catalysts with heterostructure were synthesized via a simple two-step synthetic route: (i) NaBH4 pretreatment and in situ hydrolysis, (ii) low-temperature phosphating. It was found that iron doping not only improves the dispersibility but also increases the valence state of nickel in phosphating products. The Ni5P4/Ni2P/Fe2P-2 catalyst prepared with a molar ratio of 3 between Ni and Fe exhibits the best performance for HER and OER. In detail, only 185 and 190 mV overpotentials in acidic and alkaline electrolytes are required when the current density of hydrogen production is 10 mA cm−1, respectively. To achieve the same current density under alkaline conditions, an overpotential of 215 mV is required for oxygen evolution, which is superior to IrO2. This work would enlighten the construction of more advanced bifunctional catalysts (HER and OER) via metal Fe doping.