Actualizing Anion-Cation Dual Active Sites in a Single Substance for Hydrogen Evolution

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Single-site catalysts often limit hydrogen evolution reaction (HER) activity due to disparate metallic and nonmetallic site kinetics.
• Nickel phosphide (Ni2P) typically functions as a single-active-site catalyst.

Purpose of the Study:

• To simultaneously activate both anionic (P) and cationic (Ni) sites in Ni2P.
• To enhance HER electrocatalytic activity by creating synergistic dual active sites.
• To investigate the role of NiS2-NiS heterogeneous structures as a substrate for activating Ni2P.

Main Methods:

• Fabrication of Ni2P electrocatalyst supported on NiS2-NiS heterogeneous structures.
• In situ Raman spectroscopy to probe the catalyst's electronic structure.
• Density Functional Theory (DFT) calculations to understand reaction mechanisms and charge distribution.

Main Results:

• The NiS2-NiS substrate effectively modulated charge distribution, concentrating it around the P atom.
• Synergistic Ni and P dual active sites were generated, facilitating water adsorption, dissociation, and H* adsorption.
• The resulting Ni2P/NiS2-NiS electrocatalyst achieved a low overpotential of 75 mV at 10 mA cm-2 in alkaline media.

Conclusions:

• Simultaneous activation of anion and cation sites via substrate engineering is a viable strategy to boost electrocatalyst performance.
• The NiS2-NiS substrate plays a critical role in creating dual active sites for efficient HER.
• This approach offers a pathway for developing cost-effective, high-performance electrocatalysts based on single metal/intermetallic compounds.