Hydrogen evolution descriptors of 55-atom PtNi nanoclusters and interaction with graphite

Area of Science:

• Materials Science
• Catalysis
• Computational Chemistry

Background:

• The hydrogen evolution reaction (HER) is crucial for sustainable energy production.
• Developing efficient and cost-effective electrocatalysts for HER is a key research area.
• Platinum-based materials are highly active but expensive.

Purpose of the Study:

• To investigate the catalytic properties of platinum-nickel (PtNi) clusters for the hydrogen evolution reaction (HER).
• To explore the effect of varying Pt:Ni ratios on HER activity using density functional simulations.
• To understand hydrogen adsorption energetics and electronic descriptors in PtNi clusters.

Main Methods:

• Density functional theory (DFT) simulations were employed.
• PtNi clusters of varying compositions (Pt55-nNIn, n=0,12,20,28,42,55) were studied.
• Hydrogen adsorption, electronic d-band, and magnetic properties were analyzed.

Main Results:

• PtNi clusters exhibit HER activity comparable to pure platinum (Pt55).
• Optimal differential adsorption free energies (|ΔGH|<0.1 eV) were observed.
• PtNi clusters accommodate substantial hydrogen loading (3-4 H atoms per facet).
• Magnetism in uncovered clusters is suppressed by hydrogen adsorption, leading to cluster expansion.
• Adsorption sites vary with composition: Pt-Pt bridge for Pt-rich, Ni-hollow for Pt-poor.
• Spontaneous H2 dissociation occurs on Pt-rich clusters.
• Interaction with carbon support has minor effects on cluster properties.

Conclusions:

• PtNi clusters are promising electrocatalysts for HER, offering activity comparable to Pt.
• The electronic and adsorption properties suggest efficient hydrogen turnover.
• PtNi alloys present a viable alternative to pure platinum for HER catalysis.
• The findings are applicable to PtNi supported on carbon materials.