Hydrogen embrittlement is a serious issue faced by structural metal materials in hydrogen infrastructures. The development of protective coatings as efficient hydrogen permeation barriers is urgently needed. Here, we report a new nanocrystalline CeO₂ coating with a thickness of ~40 nm successfully fabricated via the coordination-assisted deposition method. By optimizing the annealing conditions, the resultant CeO₂ coating has a uniform and dense structure, albeit with a high density of dislocations and grain boundaries. Its hydrogen permeation barrier performance was evaluated by a gas-driven deuterium permeation test, achieving an ultralow permeability of 1.64×10⁻¹⁵ mol·s⁻¹·m⁻¹·Pa^−1/2 at 500 °C, which is three orders of magnitude lower than that of stainless steel. The corresponding hydrogen permeation reduction factor (PRF) reaches an ultrahigh value of 2355, which is 4–75 times that of the other oxide nanocoatings, such as ZrO₂, Al₂O₃, Cr₂O₃, and Er₂O₃. The intrinsic hydrogen diffusion mechanism in the single-crystal coating is revealed by first-principles calculations. In the polycrystal coating, the dense dislocation and boundary-containing nanocrystalline structure not only provides abundant hydrogen traps but also prolongs the diffusion pathway to effectively impede hydrogen permeation. This study demonstrates the great potential of CeO₂ as a new type of hydrogen-resistant material and, most importantly, the roles of microstructure in the design of ultrathin hydrogen permeation barriers with high performance.

Ceramic coatings with high hydrogen permeation resistance are highly important for protecting metal components from hydrogen attack. In this work, we fabricated an ultrathin (AlCrZr)O nanofilm with superior hydrogen barrier efficiency via a facile sol‒gel technique. This novel ternary oxide nanofilm with an overall thickness of only 100 nm has a high hydrogen permeation reduction factor (PRF) of up to 2364 at 773 K, decreasing the hydrogen permeability by three orders of magnitude compared to that of the steel substrate. The permeation cycling performance and thermal shock resistance of the nanofilm were further evaluated, which demonstrated good stability, with its PRF consistently remaining at a level of 10³. These excellent performances of the (AlCrZr)O nanofilm were attributed to its uniquely layered structure, consisting of an amorphous Al‒Zr‒O layer at the top and a crystalline Cr₂O₃ layer underneath. The amorphous layer without grain boundaries complicated the hydrogen diffusion pathways and effectively increased the hydrogen resistance. Moreover, the crystalline Cr₂O₃ layer could help mitigate the thermal expansion mismatch between the nanofilm and the steel substrate, ensuring good stability of the barrier performance under thermal conditions. These findings underscore the significant potential of the (AlCrZr)O nanofilm for hydrogen embrittlement protection and provide a new framework for designing highly efficient hydrogen permeation barriers that combine superior performance with extended lifespans.

Conductive fiber networks have both high transparency and high electrical conductivity, and thus is a new type of promising alternative for replacing In doped SnO₂ (ITO) used as transparent electrodes. Even though metal fibers possess high electrical conductivity, their properties sharply deteriorate when suffering oxidation or corrosion, which severely limits their applications. In this work, novel tungsten nitride (WN) fibers were firstly fabricated by electrospinning together with nitridation treatment. Patterning of WN fibers was further achieved by near-field direct writing method, and WN fiber based transparent electrodes were successfully assembled with high transparency, high electrical conductivity, as well as anti-oxidation and-corrosion ability. The electrical conductivity of WN fibers increased with the nitridation temperature, which reached 2189 S/cm at 900 ℃. Transparency and electrical conductivity of the WN fiber transparent electrode could be optimized through regulating its network structure. A high transparency above 94% and low sheet resistance of 6.0 Ω/sq was achieved when the spacing of the WN fiber network was 200 μm. This performance even exceeds that of the metal fiber transparent electrodes as previously reported. Furthermore, as compared with metal fibers, the WN fiber transparent electrode also exhibited outstanding anti-oxidation and -corrosion ability. Its sheet resistance only increased by 8% after oxidation at 160 ℃ for 16 h, and just 3% increase in the sheet resistance happend after corrosion in a solution with pH ranging from 1 to 13 for 1 min.

Hydrogen isotope permeation through structural materials is a key issue for developing nuclear fusion energy, which will cause fuel loss and radioactive pollution. Developing ceramic coatings with high thermal shock and hydrogen resistance is an effective strategy to solve this issue. In this work, a layer-structured Cr/Cr_xN coating was successfully fabricated by a facile electroplating-based nitridation technique, which is easy, facile, and applicable to coating complex-shaped substrates. The Cr/Cr_xN coating, composed of a bottom Fe/Cr interdiffusion zone, a middle Cr layer, and a top Cr_xN layer, exhibits high bonding strength, high anti-thermal-shock ability, and high deuterium permeation resistance. Its bonding strength achieves 43.6 MPa. The Cr/Cr_xN coating remains intact even after suffering 300 thermal shock cycles under a 600 ℃–water condition. Through optimizing the nitridation temperature, the Cr/Cr_xN coating achieves a deuterium permeation reduction factor (PRF) as high as 3599 at 500 ℃. Considering its scalable fabrication technique and considerable properties, the developed Cr/Cr_xN coating may serve as a novel high-performance hydrogen permeation barrier in various fields.

To promote the energy density of symmetric all-solid-state supercapacitors (SCs), efforts have been dedicated to searching for high-performance electrode materials recently. In this paper, vanadium nitride (VN) nanofibers with mesoporous structure have been fabricated by a facile electrospinning method. Their crystal structures and morphology features were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The mesoporous structure of VN nanofibers, which can provide short electrolyte diffusion routes and conducting electron transport pathways, is beneficial to their performance as a supercapacitor electrode. Under a stable electrochemical window of 1.0 V, VN nanofibers possess an excellent mass specific capacitance of 110.8 F/g at a scan rate of 5 mV/s. Moreover, the VN nanofibers were further assembled into symmetric all-solid-state SCs, achieving a high energy density of 0.89 mW·h/cm³ and a high power density of 0.016 W/cm³ over an operating potential range from 0 to 1.0 V. These results demonstrate that VN nanofibers could be potentially used for energy storage devices.