Tuning core-shell interactions in tungsten carbide-Pt nanoparticles for the hydrogen evolution reaction

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Platinum (Pt) is a key electrocatalyst for the hydrogen evolution reaction (HER), crucial for fossil-free hydrogen production.
• Reducing platinum loading while maintaining catalytic activity is essential for cost-effectiveness.
• Core-shell nanoparticles offer a strategy to achieve this by using transition-metal carbides as supports.

Purpose of the Study:

• To investigate the suitability of alpha (α) and beta (β) phases of tungsten carbide (WC) as core materials for platinum (Pt) shells.
• To analyze the thermodynamic stability and electronic structure of Pt layers on WC supports.
• To explore the impact of alloying β-WC with titanium (Ti) on the stability and HER activity of core-shell nanoparticles.

Main Methods:

• Density-functional theory (DFT) calculations were employed.
• Thermodynamic stability of 1-2 layers of Pt on α- and β-WC surfaces was examined.
• Epitaxial mismatch strains and core-shell chemical bonding were considered.
• Electronic structures of Pt overlayers on α-WC and Ti-alloyed β-WC (β-TixW1-xC) were compared.
• Hydrogen binding energy was used as a descriptor for HER catalytic activity.

Main Results:

• Moderate Ti doping of the metastable β-WC phase enhances its stability.
• Core-shell structures with only two layers of Pt loading achieved HER activity comparable or superior to Pt(111).
• Ti alloying modulates the electronic structure, improving catalytic performance.

Conclusions:

• Ti-doped β-WC provides a stable and effective core for Pt shells in HER electrocatalysis.
• The β-TixW1-xC@Pt core-shell nanoparticles demonstrate excellent stability and high catalytic activity.
• These findings offer insights into experimental observations and guide the design of advanced electrocatalysts.