<i>In Situ</i> Growth of Nickel Phosphide on Carbon Felt as a Promising Electrocatalyst for the Alkaline Hydrogen Evolution Reaction

One of the key challenges in scaling up sustainable hydrogen production is the need for efficient electrocatalysts based on abundant elements for the hydrogen evolution reaction (HER). This study introduces a simple and scalable method for producing a binder-free NiP supported on carbon felt (NiP@CF) electrocatalyst through a hydrothermal route followed by phosphorization. The three-dimensional (3D) conductive structure of carbon felt, resembling a sponge, is crucial for immobilizing electroactive materials within its fibrous framework. The as-prepared NiP@CF electrocatalyst demonstrates remarkable performance, requiring only a low overpotential of 134 mV to achieve a current density of 10 mA cm–2 in a 1 M KOH electrolyte. Moreover, the catalyst exhibits impressive stability, maintaining its superior performance for at least 60 h without noticeable deterioration. The good performance of the NiP@CF catalyst can be attributed to several factors: the formation of electroactive Ni5P4 and NiP2 phases on the porous carbon felt, the interconnected 3D network of the substrate, which enhances electron and mass transport and improves electrolyte contact and reaction rates, and the increased electrochemical surface area, providing abundant active sites for electrochemical reactions.