Se Doping Inducing the Lattice Contraction of NiP₃ for a Highly Efficient Hydrogen Evolution Reaction

Doping cations into transition metal phosphides consistently proves intriguing and significant due to their capacity to fine-tune both the crystal and electronic structures. Herein, we present a simple method for synthesizing Se-doped NiP₃ crystals (Se/NiP₃) on nickel foam (Se/NiP₃-NF) for efficient and stable hydrogen evolution reaction (HER) performance in both alkaline and acidic solutions. Various characterizations indicate that Se doping leads to a reduction in the cell volume of the Se/NiP₃ crystal lattice, thereby causing lattice contraction. Theoretical calculations reveal that Se doping not only induces lattice contraction but also increases the electron cloud density around the P atoms while decreasing it around the Ni atoms. These charges significantly enhance both H₂O adsorption/dissociation and H desorption, thereby accelerating the Volmer and Heyrovsky steps during the HER process. The optimized Se/NiP₃-NF exhibits excellent HER performance, with overpotentials of 138 and 109.2 mV required to drive a current density of 100 mA cm^-2 in 1.0 M KOH and 0.5 M H₂SO₄ solutions, respectively. This work will inevitably promote the development of advanced non-noble metal electrocatalysts.