Stainless Steel-Supported Amorphous Nickel Phosphide/Nickel as an Electrocatalyst for Hydrogen Evolution Reaction

Recently, nickel phosphides (Ni-P) in an amorphous state have emerged as potential catalysts with high intrinsic activity and excellent electrochemical stability for hydrogen evolution reactions (HER). However, it still lacks a good strategy to prepare amorphous Ni-P with rich surface defects or structural boundaries, and it is also hard to construct a porous Ni-P layer with favorable electron transport and gas-liquid transport. Herein, an integrated porous electrode consisting of amorphous Ni-P and a Ni interlayer was successfully constructed on a 316L stainless steel felt (denoted as Ni-P/Ni-316L). The results demonstrated that the pH of the plating solution significantly affected the grain size, pore size and distribution, and roughness of the cell-like particle surface of the amorphous Ni-P layer. The Ni-P/Ni-316L prepared at pH = 3 presented the richest surface defects or structural boundaries as well as porous structure. As expected, the as-developed Ni-P/Ni-316L demonstrated the best kinetics, with eta(10) of 73 mV and a Tafel slope of ca. 52 mV dec-1 for the HER among all the electrocatalysts prepared at various pH values. Furthermore, the Ni-P/Ni-316L exhibited comparable electrocatalytic HER performance and better durability than the commercial Pt (20 wt%)/C in a real water electrolysis cell, indicating that the non-precious metal-based Ni-P/Ni-316L is promising for large-scale processing and practical use.

Automated summary

Recently, amorphous nickel phosphides (Ni-P) have been identified as potential catalysts for hydrogen evolution reactions (HER) due to their high intrinsic activity and excellent electrochemical stability. However, there is a lack of effective strategies for preparing amorphous Ni-P with surface defects or structural boundaries, as well as constructing porous Ni-P layers with favorable electron and gas-liquid transport properties. In this study, an integrated porous electrode consisting of amorphous Ni-P and a Ni interlayer was successfully fabricated on a 316L stainless steel felt (Ni-P/Ni-316L). The pH of the plating solution significantly influenced the properties of the amorphous Ni-P layer, including grain size, pore size, distribution, and surface roughness. The Ni-P/Ni-316L prepared at pH = 3 exhibited the richest surface defects or structural boundaries as well as a porous structure. The Ni-P/Ni-316L demonstrated superior kinetics, with a low overpotential (eta(10) = 73 mV) and a small Tafel slope (ca. 52 mV dec-1) for the HER compared to other electrocatalysts synthesized at different pH values. Moreover, the Ni-P/Ni-316L showed comparable electrocatalytic performance and better durability than commercial Pt (20 wt%)/C in a real water electrolysis cell, indicating its promising potential for large-scale processing and practical use.