Combining density functional theory and cluster expansion methods to predict H2 permeance through Pd-based binary...

Area of Science:

• Computational materials science
• Physical chemistry
• Solid-state physics

Background:

• First-principles calculations are valuable for studying hydrogen permeance in metal membranes.
• Predicting hydrogen solubility and diffusivity in disordered alloys presents a significant challenge.
• Existing lattice models have limitations in accurately describing interstitial hydrogen behavior.

Purpose of the Study:

• To develop a computational framework for predicting hydrogen permeance in Pd-based binary alloys.
• To accurately model interstitial hydrogen behavior in disordered Pd96M4 alloys (M=Ag, Cu, Rh).
• To assess the effectiveness of cluster expansion methods compared to simpler lattice models.

Main Methods:

• Density functional theory (DFT) calculations were employed.
• A cluster expansion method was utilized to describe interstitial hydrogen.
• Sieverts' law and kinetic Monte Carlo (KMC) simulations were used for solubility and diffusivity calculations, respectively.

Main Results:

• The cluster expansion approach revealed limitations of traditional lattice models.
• Hydrogen solubility and diffusivity were calculated for PdAg, PdCu, and PdRh alloys.
• Predictions for hydrogen permeability through these binary alloy membranes were generated.

Conclusions:

• The combined DFT and cluster expansion approach provides accurate predictions for hydrogen transport in alloys.
• This method overcomes challenges associated with local information from first-principles calculations.
• The findings enable the design of improved palladium-based alloy membranes for hydrogen separation.