Sulfur-Doped Nickel Phosphide Nanoplates Arrays: A Monolithic Electrocatalyst for Efficient Hydrogen Evolution...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Developing cost-efficient electrocatalysts for hydrogen generation is crucial for advancing energy technologies.
• Nickel phosphide and nickel sulfide are explored as potential electrocatalysts but often face limitations in activity and stability.

Purpose of the Study:

• To report high-performance hydrogen evolution reaction (HER) electrocatalysts based on sulfur-doped Ni5P4 nanoplate arrays grown on carbon paper.
• To investigate the catalytic activity, stability, and mechanism of these novel electrocatalysts for water electrolysis.

Main Methods:

• Synthesis of sulfur-doped Ni5P4 nanoplate arrays on carbon paper (S-Ni5P4 NPA/CP).
• Electrochemical characterization including onset potential, overpotential, Tafel slope, and turnover frequency measurements.
• Density functional theory (DFT) calculations to understand hydrogen adsorption free energy and doping effects.

Main Results:

• S-Ni5P4 NPA/CP exhibited remarkable HER performance with an onset potential of 6 mV and overpotentials of 56 mV and 104 mV at 10 and 100 mA cm-2, respectively.
• The turnover frequency of S-Ni5P4 NPA/CP was significantly higher (ca. 10-40 times) than undoped Ni5P4 and NiS2 counterparts.
• DFT calculations revealed a favorable hydrogen adsorption free energy (0.04 eV) for S-Ni5P4 NPA/CP, indicating enhanced catalytic activity.

Conclusions:

• Sulfur doping in Ni5P4 nanoplate arrays enhances electrocatalytic activity and stability for hydrogen evolution reaction.
• The synergistic effect of sulfur and phosphorus tunes electronic properties, creating an active phase for HER.
• This work provides a new strategy for designing efficient transition metal phosphide composite electrocatalysts for energy applications.