The free-standing nanoporous palladium for hydrogen isotope storage

Herein, we present hydrogen isotope storage properties of the free-standing monolithic nanoporous palladium (NP–Pd) with different microstructure feature sizes. The NP-Pd samples fabricated by dealloying from Pd–Al alloy and the samples possess high surface area with all of the open pores and ligaments both at nanoscale, which provide the large quantities of reaction sites. The NP-Pd exhibits efficient hydrogen (H₂) separation property from deuterium (D₂) with distinguishable absorbing and desorbing plateau pressures. The samples own high and reversible H₂ and D₂ storage capacities with the absorption values up to 0.61 and 0.595 at room temperature. The hydrogen isotope storage capacities increase with the ligament sizes of the NP-Pd samples, which have been high temperature annealed with the larger ligament size more than 10 nm. While for the fresh dealloyed NP-Pd samples with rough surface and ligament size much smaller than 10 nm, the capacity does not follow this behavior. Therefore, a theoretical model based on the existence of the different storage sites at subsurface and interior region is established, which can be used to predict the hydrogen absorption capacity of nanoporous Pd with different structure size. This work reveals both fundamental insights and practical guidance for nanoporous materials design and fabrication, which can be applied in hydrogen isotope separation and storage applications in green energy fields.