Tuning Pd–Ag–Based Alloy Membranes for Efficient Hydrogen Separation: Insights from First-Principles and Molecular Dynamics Simulations

As the demand for clean energy continues to rise, hydrogen has attracted significant attention due to its high energy density and conversion efficiency. Efficient hydrogen separation and purification technologies are crucial for its industrial application. In this study, density functional theory (DFT) calculations, combined with molecular dynamics (MD) simulations, are employed to systematically investigate the hydrogen separation performance and elucidate the underlying mechanisms of Pd–Ag-based alloy membranes (Pd–Ag–Y and Pd–Ag–Ni). Our results indicate that doping with Y and Ni significantly enhances the structural stability of the alloy membranes and effectively reduces the hydrogen diffusion energy barrier. Notably, the Pd–Ag–Y membrane demonstrates the highest hydrogen permeability. Further analysis reveals that the incorporation of Y and Ni substantially improves the hydrogen selectivity of the alloy membranes over other gases, including N2, CO, CO2, CH4, and H2S. In most cases, their selectivity exceeds industrial thresholds, further enhancing the efficiency of hydrogen separation. The MD simulation results are in excellent agreement with the DFT calculations, validating the superior performance of the alloy membranes in hydrogen separation. This study demonstrates that judicious dopant selection, especially the incorporation of yttrium (Y), can simultaneously enhance hydrogen permeability and suppress impurity transport in Pd–Ag-based membranes, offering a promising pathway for designing high-performance ternary alloy membranes for gas separation.