First-principles based modeling of hydrogen permeation through Pd-Cu alloys

TL;DR

This study combines first-principles calculations, a local cluster expansion, and kinetic Monte Carlo simulations to accurately model hydrogen permeation in Pd-Cu alloys, aligning well with experimental data and enabling rapid alloy screening.

Contribution

It introduces a linear composition-dependent cluster expansion model for hydrogen in Pd-Cu alloys that is both accurate and computationally efficient.

Findings

The model accurately predicts hydrogen solubility and permeability across the entire alloy composition range.

Local lattice relaxations significantly influence hydrogen energetics in size-mismatched alloys.

The approach can be extended to ternary and higher-order alloy systems for membrane applications.

Abstract

The solubility and diffusivity of hydrogen in disordered Pd1-xCux alloys are investigated using a combination of first-principles calculations, a composition-dependent local cluster expansion (CDLCE) technique, and kinetic Monte Carlo simulations. We demonstrate that a linear CDCLE model can already accurately describe interstitial H in Pd1-xCux alloys over the entire composition range (0\leqx\leq1) with accuracy comparable to that of direct first-principles calculations. Our predicted H solubility and permeability results are in reasonable agreement with experimental measurements. The proposed model is quite general and can be employed to rapidly and accurately screen a large number of alloy compositions for potential membrane applications. Extension to ternary or higher-order alloy systems should be straightforward. Our study also highlights the significant effect of local lattice relaxations on H energetics in size-mismatched disordered alloys, which has been largely overlooked in the literature.