First-Principles Mechanistic Insights into the Hydrogen Evolution Reaction on Ni2P Electrocatalyst in Alkaline Medium

Nickel phosphide (Ni₂P) is a promising material for the electrocatalytic generation of hydrogen from water. Here, we present a chemical picture of the fundamental mechanism of Volmer–Tafel steps in hydrogen evolution reaction (HER) activity under alkaline conditions at the (0001) and (10-10) surfaces of Ni₂P using dispersion-corrected density functional theory calculations. Two terminations of each surface (Ni₃P₂- and Ni₃P-terminated (0001); and Ni₂P- and NiP-terminated (10-10)), which have been shown to coexist in Ni₂P samples depending on the experimental conditions, were studied. Water adsorption on the different terminations of the Ni₂P (0001) and (10-10) surfaces is shown to be exothermic (binding energy in the range of 0.33−0.68 eV) and characterized by negligible charge transfer to/from the catalyst surface (0.01−0.04 e⁻). The activation energy barriers for the dissociation of water on each termination of the Ni₂P (0001) and (10-10) surfaces are determined. The Gibbs free energy of hydrogen adsorption (ΔG_H*) at different surface sites is also predicted.

The density functional theory (DFT) theoretical simulation datasets are available in the .xlsx format (can be viewed either by MS Office or Libre Office) comprising 8 datasheets which gives information about the bulk-Ni2P structure; DOS of Ni2P; H₂O molecular and dissociative adsorption structures adsorption (0001) and (10-10) surfaces; and the transition state structures for H2O dissociation. Data for the optimized structures are available in CONTCAR format of the VASP simulation program. The CONTCAR files consist of lattice parameter and atomic positions and can be viewed either by MS Office or WordPad. The density of states (DOS) data are in 2 columns: first column been the Energy (eV) and second column been the intensity of the DOS (arb. units). This DOS data can be plotted using any plotting software, e.g., xmgrace, excel.

Research results based upon these data are published at https://doi.org/10.3390/catal10030307