Ni _x Co _x P/Ni ₃ S ₂ Heterojunction for Electrocatalytic Hydrogen Evolution Reaction in Alkaline Solution

Abstract Traditional single‐component electrocatalysts designed for the hydrogen evolution reaction (HER) no longer meet the requirements of several industrial applications. This necessitates the fabrication of more advanced and state‐of‐the‐art electrocatalysts. In this work, we synthesize a new nickel foam (NF)‐supported Ni _x Co _x P/Ni ₃ S ₂ @NF heterojunction by a two‐step hydrothermal process and low‐temperature phosphorization, requiring a straightforward technique. By creatively adjusting the Co ratio to optimize its active surface area, we modify the morphology of Ni _x Co _x P/Ni ₃ S ₂ @NF. In accordance with most of the non‐precious metal HER electrocatalysts, the leading to a “ball‐like surface with rough edges and a porous structure.” Ni _2.3 CoP/Ni ₃ S ₂ @NF nanostructure shows a lower overpotential of 23.1 mV at a current density of 10 mA cm ⁻² , a Tafel slope of 52 mV dec ⁻¹ , and high activity with long‐term stability of 24‐hours at constant current density in an alkaline medium of 1.0 M KOH. Also, density‐functional theory (DFT) demonstrates that Ni _x Co _x P/Ni ₃ S ₂ @NF heterojunction exhibits no bandgap, indicating high electron mobility, which is typically associated with enhanced catalytic activity. This work highlights the novel nature of Ni _x Co _x P/Ni ₃ S ₂ @NF heterojunction as a significant advancement in the study of bifunctional electrocatalysis for HER, offering a promising path for the use of renewable energy for water splitting.