Highly active interfaces are crucial to the hydrogen adsorption performance of nanomaterials. However, it remains challenging to conveniently and efficiently regulate atomic stacking characteristics. Here, we present a straightforward yet effective strategy for generating a high density of stepped atoms at the surface of thin films by controlling the migration behavior of sputtered atoms during deposition. Tuning sputtering power and substrate temperature yields wide-scale stepped interface structures, thus generating irregular conical columnar nanocrystals. Benefiting from the active and stable stepped atoms at the zigzag interface, the samples exhibit an excellent threshold pressure at 200 °C and a hydrogen adsorption of 110.06 cm³/g at 6 MPa, which is 2.2 times higher than that of conventional Pd thin films. Based on the control of nucleation and crystal growth during magnetron sputtering deposition, this method provides appropriate energy for surface atomic migration on columnar crystals, achieving high-density stepped interface structures. It can be readily extended to other substrates and noble metal systems, thus offering a novel strategy and guidance for the design of efficient and cost-effective hydrogen-interactive materials.

The large-scale and engineering preparation of NiPd powder with an excellent structure is crucial for promoting the development of catalytic applications and the utilization of hydrogen energy. In this study, micro-nano dual-size NiPd alloy with a flake-like microstructure was synthesized using a simple and efficient high-energy ball milling method. Micro-structural analysis was performed on samples at various stages of ball milling to investigate the atomic migration and refinement mechanisms during the process. The microstructure and elemental distribution at different stages of particle refinement were examined, and the particle size distribution of NiPd alloy at varying ball milling times was statistically analyzed. The NiPd alloy produced using this method exhibits two distinct structural features: a flake-like polycrystalline structure and a dual-size nanocrystalline structure. A flake-like polycrystalline powder was achieved using relatively short ball milling durations and characterized by a polygonal two-dimensional structure with a single particle aspect ratio of 24. After 60 h of ball milling, the NiPd alloy developed a dual-size nanocrystalline structure. Under a high ball-to-powder ratio, the average particle size of the alloy decreased to 3.6 μm, more than tenfold smaller than the initial size. The alloy particles transformed from their original elemental metals into alloy phases, with nanoscale alloy particles (approximately 158 nm) adhering to micrometer-sized alloy particles. Additionally, the influence of the ball-to-powder ratio on the refinement process and outcomes was investigated, indicating that a higher ball-to-powder ratio can effectively improve preparation efficiency by accelerating the ball milling process and reducing the final particle size of the NiPd alloy at each milling stage.

In cold fusion research, the LiOD heavy water solution has been used as electrolyte in Pd-D2O electrolytic systems for over 30 years. The conductivity of LiOD not only affects the electrical and thermal properties but also can be used to determine the LiOD concentration. In this paper, conductivities of LiOD heavy water solution (0.01409 ∼ 0.09721 mol·L−1) at 10 ∼ 70◦C were measured. Changes of conductivity κ in mS·cm−1 with concentration c in mol·L−1 and temperature T in ◦C can be expressed by the quadratic form: κ = 60.56c – 14.25c2 + 2.514cT – 0.5459c2T. This relationship can be simplified to κ = 123.41c – 27.90c2 or c=8.1031×10−3 κ+1.484×10−5 κ2 at25◦C.