Activating HfX₂ (X = S, Se and Te) for the hydrogen evolution reaction by introducing defects: a first-principles...

Area of Science:

• Materials Science
• Computational Chemistry
• Electrochemistry

Background:

• An ideal catalyst for the hydrogen evolution reaction (HER) should exhibit a relative hydrogen adsorption Gibbs free energy (ΔG_H) near zero.
• Most existing catalysts fall short of this ideal benchmark, necessitating the search for superior materials.

Purpose of the Study:

• To computationally investigate the HER catalytic performance of pristine and defect-engineered hafnium disulfide (HfS₂) and hafnium diselenide (HfSe₂) structures.
• To identify novel catalyst materials with ΔG_H values approaching the theoretical ideal.

Main Methods:

• First-principles calculations were employed to simulate and evaluate the catalytic properties.
• The study focused on analyzing the ΔG_H for various pristine and defect structures, including vacancies and heteroatom doping.

Main Results:

• Co-doped HfS₂ and P-doped HfSe₂ exhibited ΔG_H values exceptionally close to zero, surpassing even those of Pt (111).
• The enhanced HER performance of Co-doped HfS₂ was attributed to the reduction of electron accumulation at the active sulfur (S) atom site.

Conclusions:

• Co-doped HfS₂ and P-doped HfSe₂ emerge as promising candidates for ideal HER catalysts.
• This research offers valuable insights and guidance for experimental efforts in discovering and synthesizing efficient electrocatalysts.