High-density Hydrogen Research Articles

Organohydrogel Based Electronic Skin Reinforced by Dual-Mode Conduction and Hierarchical Collagen Fibers Skeleton.

Collagen fiber skeleton from animal skin is an ideal substrate for electronic skin (e-skin). However, the interface mismatch between conductive materials and skeleton and the monotonicity of conductive network still hinder its creation. Herein, a novel collagen fiber-based e-skin with dual-mode conduction of NaCl and conductive spheres (IECS) is accomplished by loading organohydrogel into the skeleton via "permeation and self-assembly". The resulting interpenetrating network produces a 3D continuous, conductive pathway and strong interface interaction with high-density hydrogen bonding, thus exhibiting excellent strength (24.5MPa), conductivity (14.82Sm-1), sensing performance (sensitivity of 16.64), and environmental stability. The physical structure (3D skeleton, interpenetrating network) and chemical interaction (interface interaction, salting-out) achieve energy dissipation. Meanwhile, the sensitivity is enhanced by dual-mode conduction, conductive sphere array, and deformation amplification induced by collagen fibers. Additionally, the strong bonding ability between glycerin and collagen fibers with water molecules provides anti-freezing and moisture-retention characteristics. Thus, the strategic synergy of compositional and structural design makes IECS a promising force-sensing part of piezoresistive sensor for human movement, pulse frequency, cipher transmission, and pressure distribution. In short, IECS presents a multifunctional platform for the invention of high-performance e-skin with on-demand property, which offers great application potential in wearable electronics.

Unveiling the incorporation of dual hydrogen-bond-donating squaramide moieties into covalent triazine frameworks for promoting low-concentration CO2 fixation

The development of multi-functional materials for low-concentration CO2 fixation into organic carbonates remains a significant challenge. Herein, we constructed several covalent triazine frameworks modified with squaramide moieties (SCTF-R; R = H, F, CF3) using a facile ZnCl2-mediated trimerization approach. The as-prepared SCTFs possess high surface areas (605–833 m2/g) and incorporate high-density hydrogen bond donors as well as CO2-affinity sites. They demonstrate good CO2 adsorption capacity of up to 2.5 mmol/g at 273 K and 1.0 bar CO2 pressure. Notably, the SCTF-CF3 combined with KI exhibits excellent performance in converting low-concentration CO2 into bromopropene carbonate with a yield of 96 % and selectivity of 99 % under mild and metal-/solvent-free conditions. Furthermore, the SCTF-CF3/KI system demonstrates outstanding reusability and versatility. By combining in-situ FT-IR monitoring with DFT calculations, we elucidate the significant contribution of squaramide moieties and reaction mechanism. This work provides an innovative approach for clean and efficient utilization of low-concentration CO2.

Dynamically reshaping high density hydrogen bonds enhanced polyurethane used as artificial heart valves with enhanced fatigue resistance, anti-calcification and blood compatibility

Injury to cardiac valves is a major contributor to mortality associated with cardiovascular diseases. Artificial valves are preferred for their mimicry of natural valve efficiency in optimizing hemodynamics and minimizing associated complications. To endure the substantial pressures of the cardiovascular system, these valves require exceptional fatigue resistance, calcification resistance, and blood compatibility. To address these demands, we have designed and synthesized a silane uniformly integrated polyurea-polyurethane elastomer (PSCU). The PSCU features a highly responsive hydrogen bond network, conferred by the integration of oxygen-containing spirochemical rings and polyurethane urea segments, which forms orientation to prevent material fatigue damage. Concurrently, PSCU has almost no adverse effects on the blood due to the uniform integration of silane, and long-term use will not cause calcification. In vivo evaluations have confirmed PSCU’s exceptional biocompatibility and stability, with no observable tissue inflammation or material accumulation. Moreover, fluid dynamics studies have demonstrated PSCU’s superior mechanical attributes, maintaining effective unidirectional blood flow under a sustained 60 mmHg pressure gradient. This breakthrough material represents a significant advancement in the field of cardiovascular medicine, offering enhanced durability and reliability for artificial heart valves.

Ion-Conducting Polymers with Intermolecularly Interacting Groups for Improved Cell Performance and Durability of Anion Exchange Membrane Water Electrolysis

Green hydrogen production technology has drawn much interest due to its high energy density and eco-friendly energy production of hydrogen. In particular, anion exchange membrane water electrolysis (AEMWE) have been at the core of recent research because of the low cost of hydrogen production by using a non-precious metal catalyst and non-fluorinated ion-conducting polymer electrolyte membranes. Nevertheless, the poor durability and low performance of AEMWE, due to chemical degradation of AEMs in alkaline conditions and the low diffusivity of OH-, need to be addressed for practical use of AEMWE. In this study, we developed a novel ion-conducting polymers with intermolecularly interacting groups as novel AEMs. This newly developed polymer-based AEMs, exhibited high ion conductivity and excellent alkaline stability, and showed good WE cell performance and durability when applied to AEMWE. The use of this polymer as an ionomer in AEMWE application also showed a promising result. The details of the synthesis, characterization of the new polymers, and AEMWE cell performance will be detailed.

Pressurizing the Fuel Cell in a Direct Hybrid System for Airborne Applications

The push towards achieving emission-free aviation is intensifying. The number of demonstrator aircraft like the HY4 form H2FLY or the ATR72 from Universal Hydrogen taking flight and gaining experience in electric aviation is increasing. One existing approach for the realization of an all-electric aircraft is a direct hybrid system comprising a fuel cell and a battery. During high-power phases of a mission, such as takeoff and climb, both the battery and the fuel cell contribute power. However, during cruise, power is solely supplied by the fuel cell to leverage the high energy density of hydrogen. In a direct hybrid system, the power share of the fuel cell and the battery is determined by the size and the operating conditions of both.The low ambient pressures at high altitude negatively affect the performance of fuel cells. This is not only important in fuel cell only propulsion systems but also when operating a direct hybrid system. The impact of low pressures on the behavior of a direct hybrid system, linking a fuel cell and a battery without a DC/DC converter, is demonstrated. The effects of a non-pressurized PEM-fuel cell in a direct hybrid with a lithium-ion battery in a low-pressure environment was analyzed previously (see attached figure).However, since weight and volume are crucial factors in an aircraft, the fuel cell reactants can be pressurized to increase the power density of the system. Pressurization improves the fuel cells performance and therefore reduces weight and volume of the system, but the pressurization of the ambient air to the desired inlet pressure of the fuel cell cathode requires energy. The pressurization of a fuel cell also changes its voltage power behavior, which in turn affects the operation of the direct hybrid system.In order to examine and analyze the influence of pressurization on the overall system performance, an open-source two-phase model of a fuel cell is used and compared to experimental measurement data to gain fuel cell data at different pressure levels.The behavior of the direct hybrid system at different operating conditions will be presented, where the net power of the pressurized PEM-fuel cell system is combined with a battery to form a direct hybrid system. At lower state of charge (SOC) levels, the share of the fuel cell increases due to the lower voltage level of the battery over all power levels. In a pressure-driven fuel cell system, we take advantage of the fact that the pressure of the reactants can be controlled. By adjusting the pressure, the power share of the fuel cell and battery can be actively controlled. Lower operating pressure results in a higher battery share, due to the lower fuel cell voltage. By increasing the pressure, the voltage level provided by the fuel cell increases and therefore the power share of the fuel cell also increases.In addition, a realistic flight mission is analyzed with a constant compression ratio for the fuel cell air supply resulting in variable operating pressures of the fuel cell during flight, due to the different environmental pressures. The performance of the pressurized fuel cell direct hybrid under those varying ambient conditions will be presented. Figure 1

Investigating the Effect of Alkali Metal Cations on Electrochemical Ammonia Oxidation Reaction on Polycrystalline Platinum Electrode

It is widely recognized that hydrogen is an appropriate fuel for the sustainable energy system because it can be utilized as an energy storage material of intermittent renewable energy sources, and it generate no environmentally harmful products after combustion. However, in region where green hydrogen production cannot follow the need, import is necessary. In this case, transportation and storage of pure hydrogen can be a problem because of the high cost of maintaining liquefied state and low amount of hydrogen in compressed gas. In this regard, ammonia has received much attention as a hydrogen carrier with advantageous properties of relatively mild condition for liquefaction, high volumetric density of hydrogen, and no carbon content. Electrochemical ammonia oxidation reaction (AOR) to extract the hydrogen has been researched as much less energy is required for electrolysis when replacing oxygen evolution reaction to the AOR in aqueous alkaline condition. But high overpotential even when the most active electrocatalyst, platinum, is used and rapid poisoning by strongly adsorbed N species inhibit the practical application. To deal with these problems, there are a lot of on-going researches with various methods and perspectives. In this study, we investigated the effect of alkali metal cations on electrochemical AOR on polycrystalline platinum electrode. With same concentration but different alkali metal cations, measured the activity of platinum was different for the AOR peak (K+ > Na+ > Li+ ≈ Cs+). The reaction kinetics were also affected, supported by the electrochemical impedance spectroscopy and Tafel slope. Also, we checked that the alkali metal cation promotes the AOR by comparing the cyclic voltammetry results with and without the cation in ammonia solution. These kinds of cation effects are also demonstrated in other electrochemical reactions including the hydrogen evolution reaction, carbon dioxide reduction reaction, nitrogen reduction reaction, and oxygen evolution reaction. Mainly, there are two explanations i) the degree of interaction between cations and water structure and reaction intermediates at the interface, ii) the local electric field between electrode and hydrated cation in electric double layer. We will present and discuss the effect of alkali metal cations on the AOR in this point of view and competitive adsorption of water, proton, hydroxide and ammonia on the platinum surface in aqueous alkaline electrolyte.

(Digital Presentation) Catalytic Nanoparticles and Sustainable Carbon-Based Supports for Efficient Hydrogen Production for Advancing Hydrogen Energy

One promising approach to hydrogen storage is the use of hydrogen feedstock materials such as sodium borohydride (NaBH4) [1-19]. Sodium borohydride is particularly noteworthy due to its high hydrogen content, containing 10.8% hydrogen by weight. This high hydrogen density makes it an attractive candidate for efficient storage. NaBH4 can release hydrogen gas when it reacts with water, a process that, although slow, can be enhanced through the use of catalysts. Catalysts are crucial in increasing the rate of hydrogen production, making the process more viable for practical applications.This comprehensive study aims to explore the catalytic efficacy of metal nanoparticles when paired with environmentally sustainable catalyst support materials derived from fused carbon microspheres and graphene-like materials [1-19]. The choice of support materials is critical, as they not only stabilize the metal nanoparticles but also enhance their catalytic performance. These support materials, sourced from renewable origins, are combined with a spectrum of metal nanoparticles, including gold, silver, platinum, palladium, and copper nanoparticles. The synergy between the nanoparticles and the support materials is expected to catalyze the expedited release of hydrogen from sodium borohydride, thereby contributing to the streamlined and efficient production of this clean and abundant energy source.One of the challenges in using nanoparticles as catalysts is their tendency to agglomerate into larger particles over time. This agglomeration significantly diminishes their catalytic efficiency, as the surface area available for catalytic reactions is reduced. To address this issue, recent research within our team has focused on incorporating carbon-based materials as support structures for nanoparticles. These carbon materials facilitate better nanoparticle dispersion, preventing agglomeration and maintaining high catalytic activity.Composite materials that combine silver, gold, platinum, palladium, and copper nanoparticles with carbon nanotubes have demonstrated competitive catalytic activity in the hydrolysis of NaBH4 [1-19]. The introduction of carbon nanotubes as a support material enhances the dispersion of nanoparticles and improves their stability, leading to more efficient hydrogen production [1-19].In conclusion, the integration of metal nanoparticles with sustainable carbon-based support materials offers a promising pathway for advancing hydrogen production technologies. References Biehler, E.; Quach, Q.; Abdel-Fattah, T.M. Catalysts 2024, 14, 423.Biehler, E.; Quach, Q.; Abdel-Fattah, T.M. Energies 2024, 17, 3327.Biehler, E.; Quach, Q.; Abdel-Fattah, T.M. J. Compos. Sci. 2024, 8, 270.Abdel-Fattah, T.M.; Biehler, E. Review. Adv. Carbon J. 2024, 1, 1–19.Biehler, E.; Quach, Q.; Abdel-Fattah, T.M. ECS J. Solid State Sci. Technol. 2023, 12, 081002. Quach, Q.; Biehler, E.; Elzamzami, A.; Huff, C.; Long, J.M.; Abdel-Fattah, Catalysts. 2021, 11, 118.Huff, C.; Quach, Q.; Long, J.M.; Abdel-Fattah, T.M. ECS J. Solid State Sci. Technol. 2020, 9, 101008.Huff, C.; Dushatinski, T.; Barzanji, A.; Abdel-Fattah, N.; Barzanji, K.; Abdel-Fattah, T.M. ECS J. Solid State Sci. Technol. 2017, 6, M69.Huff, C.; Long, J.M.; Aboulatta, A.; Heyman, A.; Abdel-Fattah, T.M. ECS J. Solid State Sci. Technol. 2017, 6, 115–118.Huff, C.; Long, J.M.; Heyman, A.; Abdel-Fattah, T.M. ACS Appl. Energy Mater. 2018, 1, 4635–4640.Huff, C.; Dushatinski, T.; Abdel-Fattah, T.M.; International Journal of Hydrogen Energy 2017, 42 (30), 18985-18990.Dushatinski, T., Huff, C.; Abdel-Fattah, T.M. Applied Surface Science 2016, 385, 282-288Huff, C.; Long, J.M.; Abdel-Fattah, F.M. Catalysts 2020, 10, 1014.Huff, C.; Biehler, E.; Quach, Q.; Long, J.M.; Abdel-Fattah, T.M. Colloid Surf. A 2021, 610, 125734Quach, Qui, Erik Biehler, and Tarek M. Abdel-Fattah. Journal of Composites Science, 7, 279 (2023).Biehler, Erik, Qui Quach, and Tarek M. Abdel-Fattah Materials 16, 4779 (2023).Quach, Qui, Erik Biehler, and Tarek M. Abdel-Fattah Catalysts 13, 1117 (2023). Biehler, Erik, Qui Quach, and Tarek M. Abdel-Fattah Nanomaterials 13, 1994 (2023). Biehler, Erik, Qui Quach, and Tarek M. Abdel-Fattah Energies 16, 5053 (2023).

Enhanced hydrolysis of MgH₂ by transition metal oxides and NaH: Performance, mechanisms, and optimization

MgH₂ is recognized as a promising material for hydrogen production due to its high hydrogen density, abundant availability, and non-polluting hydrolysis by-products, making it a viable hydrogen source for fuel cells. This study, for the first time, investigates the hydrogen production performance of the MgH₂-MOx-NaH (M = Ti, Zr, Mo, Fe, V, Bi) system, which exhibits remarkable hydrolysis properties in aqueous solutions. A series of MgH₂-MOx-NaH composite powders were synthesized via mechanical ball milling. The results revealed that V₂O₅-NaH and Bi₂O₃-NaH significantly enhanced the hydrolysis performance of MgH₂ for hydrogen production. Specifically, Bi₂O₃-NaH and V₂O₅-NaH effectively refined MgH₂ particles and mitigated agglomeration during the milling process. Hydrolysis tests demonstrated that the conversion rate and the hydrogen generation rate (mHGR) of composites initially increased with ball milling time and then decreased. The maximum hydrolysis hydrogen production yield and conversion rate for MgH₂-Bi₂O₃-NaH and MgH₂-V₂O₅-NaH composites occurred at a ball milling duration of 10 hours, and reached up to 1354.1 mL g⁻¹ (88.5 %) and 1273.5 mL g⁻¹ (81.8 %), respectively, within 8 minutes. Kinetic tests of hydrolysis hydrogen production showed that the reaction rate and hydrogen conversion increased with elevated hydrolysis temperatures. The activation energies for the hydrolysis of MgH₂-MOx-NaH (M = Ti, Zr, Mo, Fe, V, Bi) were calculated from the hydrolysis-hydrogen production curves using the Arrhenius formula, yielding values of 41.32, 37.66, 36.40, 34.60, 30.80, and 27.17 kJ mol⁻¹, respectively. The lower activation energies for hydrolysis indicate improved reaction kinetics, suggesting that the incorporation of transition metal oxides and sodium hydride effectively enhances both the hydrolytic conversion and reaction rate of MgH₂.

Dynamic stable Pt13 clusters anchored on isolated ZnOx nanorafts for efficient cycloparaffin dehydrogenation

Methylcyclohexane (MCH) has attracted wide attention as liquid organic hydrogen carriers for safe alternative and high gravimetric hydrogen density. Pt13 cluster with its fascinating structure exhibits excellent performance in cycloalkane dehydrogenation reactions accompanied by balanced C-H cleavage capability. However, the controllable synthesis of stable Pt13 clusters under reaction conditions remains challenging. Herein, we successfully synthesized low-coordinated Pt13 clusters anchored by isolated ZnOx nanorafts on silanol-rich self-pillared zeolite nanosheets (SP-S-1). In situ XAFS spectra combined with theoretical calculations revealed that Pt13 clusters exhibited strong interfacial Pt-Zn bonds and reduced d-band center through orbital hybridization (Zn 3d - Pt 5d), facilitating C-H bond cleavage and toluene desorption. The optimized catalyst exhibited superior MCH dehydrogenation activity and durability, achieving a hydrogen production rate of 3457.9 mmolH2 gPt−1 min−1 at 400 ˚C and maintaining stable for over 100 hours. This study precisely synthesizes dynamic stable Pt13 clusters and provides valuable insights into the dehydrogenation mechanism.

Healable, Recyclable, and Ultra-Tough Waterborne Polyurethane Elastomer Achieved through High-Density Hydrogen Bonding Cross-Linking Strategy.

With the increasing popularity of elastomers in industry and daily life, their high performance and functionality have attracted widespread attention. However, it is a great challenge for them to possess both high mechanical properties and excellent healing and recovery capabilities due to the limitations of the preparation methods and the intrinsic microstructure of the elastomers. In this study, a strategy of ice-controlled interfacial stepwise cross-linking was proposed to prepare the waterborne polyurethane-based elastomers with ultrahigh-density hydrogen bonding interaction achieved by enhancing the utilization rate of phenol hydroxyl groups of tannic acid to the maximum extent. The elastomers have incredible mechanical properties, including ultrahigh toughness of 1.03 GJ m-3 (which represents the highest level among polyurethane elastomers prepared through common processing techniques to date), extremely high true fracture stress of ∼1.9 GPa, world-record fracture energy of 520 kJ m-2, and exciting multiple functional characteristics, such as highly efficient self-healing ability of 10 min, high resistance to physical damage and chemical corrosion, broad temperature and frequency damping effects, good shape memory effect, and excellent melt-processing recyclability and solvent recyclability. These robust multifunctional elastomers represent considerable potential in various fields, from defense and military industry and civil transportation to precision manufacturing, etc.

Polymerization-Induced Self-Assembly Providing PEG-Gels with Dynamic Micelle-Crosslinked Hierarchical Structures and Overall Improvement of Their Comprehensive Performances.

Polymer gels are fascinating soft materials and have become excellent candidates for wearable electronics, biomedicine, sensors, etc. Synthetic gels usually suffer from poor mechanical properties, and integrating good mechanical properties, adhesiveness, stability, and self-healing performances in one gel is more difficult. Herein, polymerization-induced self-assembly (PISA) providing PEG-gels with an overall improvement in their comprehensive performances is reported. PISA synthesis is carried out in PEG (solvent) to efficiently produce various nanoparticles, which are used as the nanofillers in the subsequent synthesis of PEG-gels with dynamic micelle-crosslinked hierarchical structures. Compared to hydrogels, PEG-gels show excellent long-term stability due to the nonvolatile feature of PEG solvent. The hierarchical PEG-gels (with nanofillers) exhibit better mechanical and adhesive properties than the homogeneous-gels (without nanofillers). The energy dissipation mechanism of the PEG-gels is analyzed via stress relaxation and cyclic mechanical tests. High-density hydrogen bonds between the micelles and PAA matrix can be broken and reformed, endowing better self-healing properties of the dynamic micelle-crosslinked PEG gels. This work provides a simple strategy for producing hierarchical structural gels with enhanced properties, which offers fundamentals and inspirations for the designing of various advanced functional materials.

Achieving superior hydrogen sorption kinetics of MgH2 by addition of Ni-doped TiO2 catalysts

MgH2 is a high-density hydrogen storage material but requires an efficient catalyst to improve its poor kinetics and reduce high operating temperature. TiO2 is a widely used photocatalyst for water splitting and hydrogen production, and has also demonstrated catalytic ability in the gas-solid reaction of MgH2. In this study, we synthesize the Ni-doped TiO2 nanoparticles, which significantly reduce the hydrogen absorption temperature down to subzero temperatures. The milled composite of MgH2 with 10 wt% Ti(5Ni)O2 can absorb 5.25 wt% H2 within 30 s at 25 °C, 4.30 wt% H2 within 50 s at 0 °C, and 3.94 wt% H2 within 50 s even at a low temperature of −30 °C. This composite can release 6.04 wt% of hydrogen in 3 min at 250 °C, and the dehydrogenation activation energy is reduced to 74.57±1.36 kJ/mol, a notable reduction in comparison to that observed in pure MgH2. This study demonstrates the potential of the modified TiO2 as an important kind of catalyst for solid-state hydrogen storage materials.

Prospects for Long-Distance Cascaded Liquid—Gaseous Hydrogen Delivery: An Economic and Environmental Assessment

As an important energy source to achieve carbon neutrality, green hydrogen has always faced the problems of high use cost and unsatisfactory environmental benefits due to its remote production areas. Therefore, a liquid-gaseous cascade green hydrogen delivery scheme is proposed in this article. In this scheme, green hydrogen is liquefied into high-density and low-pressure liquid hydrogen to enable the transport of large quantities of green hydrogen over long distances. After long-distance transport, the liquid hydrogen is stored and then gasified at transfer stations and converted into high-pressure hydrogen for distribution to the nearby hydrogen facilities in cities. In addition, this study conducted a detailed model evaluation of the scheme around the actual case of hydrogen energy demand in Chengdu City in China and compared it with conventional hydrogen delivery methods. The results show that the unit hydrogen cost of the liquid-gaseous cascade green hydrogen delivery scheme is only 51.58 CNY/kgH2, and the dynamic payback periods of long- and short-distance transportation stages are 13.61 years and 7.02 years, respectively. In terms of carbon emissions, this scheme only generates indirect carbon emissions of 2.98 kgCO2/kgH2 without using utility electricity. In sum, both the economic and carbon emission analyses demonstrate the advantages of the liquid-gaseous cascade green hydrogen delivery scheme. With further reductions in electricity prices and liquefication costs, this scheme has the potential to provide an economically/environmentally superior solution for future large-scale green hydrogen applications.

Influence of dislocation cells on hydrogen embrittlement in wrought and additively manufactured Inconel 718

Hydrogen embrittlement (HE) is a major issue for the mechanical integrity of high-strength alloys exposed to hydrogen-rich environments, with diffusion and trapping of hydrogen being critical phenomena. Here, the role of microstructure on hydrogen diffusion, trapping and embrittlement in additively manufactured (AM) and wrought Inconel 718 is compared, revealing the key role played by dislocation cells. Trapping behaviour in hydrogen-saturated alloys is analysed by thermal desorption spectroscopy and numerical simulations. A high density of hydrogen traps in cell walls, attributed to dense dislocations and Laves phases, are responsible for the local accumulation of hydrogen, causing significant loss in strength, and triggering cracking along dislocation cell walls. The influential role of dislocation cells alters fracture behaviour from intergranular in the wrought alloy to intragranular for the AM alloy, due to the large proportion of dislocation cells in AM alloys. In addition, the cellular network of dislocations accelerates hydrogen diffusion, enabling faster and deeper penetration of hydrogen in the AM alloy. These results indicate that the higher HE susceptibility of nickel superalloys is intrinsically associated with the interaction of hydrogen with dislocation walls.

Ultrafine Pd nanoparticles confined in naphthalene-based covalent triazine frameworks for efficient and stable hydrogen production from formic acid

Formic acid (FA) is considered as a kind of promising hydrogen storage materials due to its economic feasibility, safety, stability and high hydrogen density. Nevertheless, it is a challenge to design a high-performance catalyst with high activity, selectivity and stability for the dehydrogenation of FA to generate hydrogen (H2). Herein, a range of covalent triazine frameworks (CTFs including 1,8-CTF, 1,5-CTF and 2,3-CTF) with abundant nitrogen atoms are developed to support palladium nanoparticles for efficiently catalyzing FA dehydrogenation. Ultrasmall palladium nanoparticles with a size of 1.2 ± 0.3 nm showed near 100 % H2 selectivity and high catalytic activity in FA dehydrogenation supported by 1,8-CTF. The activation energy of FA dehydrogenation catalyzed by Pd/1,8-CTF reaches 26.17 kJ·mol−1. In addition, Pd/1,8-CTF exhibits high stability and easy recyclability, and the catalytic activity is maintained even after 6 cycles. This work gives a feasible strategy to develop high-efficiency and selective nanocatalysts for H2 production from FA dehydrogenation.

Supercooling-Driven Homogenization and Strengthening of Hydrogel Networks.

By leveraging principles from metal grain refinement, we introduce a transformative technique for fabricating poly(vinyl alcohol) (PVA) hydrogels via supercooling-coupled wet annealing, significantly enhancing their mechanical robustness and isotropy while maintaining their exceptionally high water content. Our methodology involves the dissolving PVA in water at elevated temperatures, mirroring the homogeneity achieved with a molten metal, in order to ensure a uniform distribution of polymer chains. This uniformity facilitates a rapid cooling phase that generates ultrafine ice crystals, setting the stage for a crucial solvent exchange with ethylene glycol (EG). The EG-mediated supercooling technique ensures the polymer homogeneity and structure integrity and induces the PVA chains to aggregate and form high-density hydrogen bonds, leading to a uniformly distributed, interconnected PVA network with high crystallinity. The process is further strengthened by EG-enabled wet annealing, which promotes the formation of densely packed crystalline domains within the polymer network. This rigorous process yields PVA hydrogels with superior mechanical properties, including a tensile strength of 13.65 MPa and a fracture toughness of 35.39 MJ m-3, alongside remarkable water content nearing 80%. These advances not only surpass the capabilities of conventional hydrogels but also broaden their application potential, highlighting the innovative integration of supercooling principles in polymer science.

Tannic acid one-step induced quaternized chitin-based edible and easy-cleaning coatings with multifunctional preservation for perishable products

The development of biomass hydrogel coatings is significant for fruit preservation. This paper presents the facile development of a multifunctional polysaccharide-based hydrogel produced from quaternized chitin (QC) and tannic acid (TA) by in situ rapid cross-linking with high-density hydrogen bonding using the sample mixing method. The Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) spectra, and thermogravimetric analysis (TGA) proved that QC-TA hydrogel was formed by physical interactions (hydrogen bonding, electrostatic interaction, etc.). Moreover, the cross-linking density of the QC-TA hydrogels was analyzed by rheological property measurements and scanning electron microscope (SEM) morphology observations. This polysaccharide-based hydrogel, QC-TA, was evaluated as an edible coating for perishable food items, demonstrating significant improvements in physic-chemical properties, oxidation resistance, and antimicrobial activity against key pathogens (E. coli, S. aureus, and C. albicans). Notably, the hydrogel formed a protective film that effectively shields fruits from mechanical damage, maintaining freshness and extending shelf life, and also featuring with easy cleaning. Applied to cherry tomatoes, the QC-TA coating ensured a smooth, uniform surface, reducing dehydration and flavor loss while inhibiting microbial growth. These findings underscore the potential of employing polyphenol induced polysaccharide forming green hydrogel coatings as an economical, efficient strategy for enhancing the quality and safety of perishable foods, representing an advancement in the field of sustainable food packaging.

The study of design and performance improvement of catalysts for the stepwise production of bicyclohexane from benzene and cyclohexene

Bicyclohexane is a hydrogen storage reagent with high hydrogen density and low boiling point. Compared with the hydrogenation of biphenyl, the alkylation of benzene and cyclohexene to cyclohexylbenzene and hydrogenation is a promising way to prepare cyclohexane on a large scale. The research and development of high-efficiency cyclohexyl benzene hydrogenation catalyst should be further developed based on mature alkylation technology. This paper used an acidified USY molecular sieve to catalyze the alkylation of benzene and cyclohexene to cyclohexylbenzene, which achieved 100% conversion and selectivity. Furthermore, Pt/TiO2/γ-Al2O3 catalyst is prepared by pre-deposition TiO2 film of different thicknesses on γ-Al2O3 surface and then supported with platinum particles by Atomic layer deposition (ALD). The role of TiO2 film in improving the cyclohexylbenzene hydrogenation performance of the catalyst is studied. TEM, CO pulse chemisorption, CO-DRIFTs, quasi-in situ XPS, H-D exchange, and H2-TPR characterization show that compared with Pt/γ-Al2O3, TiO2 thin films on Pt/TiO2/γ-Al2O3 do not change the dispersion of Pt particles, but can form new Pt-TiO2 interactions. The hydrogenation performance of cyclohexylbenzene was improved by increasing the electron density and the proportion of planar active sites on the surface of platinum and reducing the energy barrier of hydrogen spillover. The research provides theoretical support for further bicyclohexane organic liquid hydrogen storage reagent development. The relevant metal-support interaction regulation strategy can be applied to the development of efficient catalysts for other aromatic molecules hydrogenation.

Facile synthesis of high-performance and self-healing polyurethane-urea nanocomposites reinforced with graphene

In this study, a facile method was employed to synthesize strong, yet highly elastic polyurethane-urea (PUU) with typical characteristics and 94 ​% optical transmittance. Graphene platelets (GNPs) were prepared and modified via a scalable and eco-friendly mechanochemical approach. The produced GNPs is at 1.6-nm thickness with high electrical conductivity of ∼950 ​S/m. The structure-property relations of PUU/GNP nanocomposites were comprehensively investigated through morphology and mechanical properties measurements. The strong interface and high-density hydrogen bonds between modified GNPs (M-GNPs) and PUU significantly enhanced the mechanical properties of the PUU nanocomposite. The PUU composite showed 66.7 ​% and 36.2 ​% increments in tensile and impact strengths, respectively, at 0.2 ​wt% M-GNPs. The reversible hydrogen bond between M-GNPs and PUU endowed the nanocomposite with self-healing properties achieving 97.8 ​% healing efficiency of the strength after 5 ​h at 120 ​°C. This study demonstrates the importance of surface modification and provides a simple yet robust approach for preparing high-performance and functional PUU/graphene composites.

Self-healing cellulose nanocrystals/fluorinated polyacrylate with double dynamic interactions of coumarin groups and multiple hydrogen bonds

In this work, self-healing cellulose nanocrystals/fluorinated polyacrylate with dual dynamic networks of photoreversible crosslinking network and high-density hydrogen bonds was prepared by Pickering emulsion polymerization. The main work was to study the effects of 7-(2-methacryloyloxy)-4-methylcoumarin (CMA) and 2-ureido-4[1H]-pyrimidinone methyl methacrylate (UPyMA) monomer dosage on emulsion polymerization and latex film properties. The monomer conversion increased first and then decreased as the CMA and UPyMA monomer dosage increased, while a reverse trend was noted for the particle size and particle size distribution. Incorporating UPyMA allowed the rapid formation of hydrogen bonds at the crosslinking sites, which increased the interaction force between the healing surfaces. Besides, reversible photocrosslinking reaction of coumarin groups provided another support for self-healing performance. Moreover, the influence of self-healing temperature, self-healing time and UV irradiation on the self-healing ability was also systematically investigated The tensile strength of the prepared cellulose nanocrystals/fluorinated polyacrylate latex film exhibited a self-healing efficiency of 91.4 % under 365 nm UV irradiation and 80 °C for 12 h. The latex film had excellent thermal stability as was shown by TG and DTG analyses. The outstanding self-healing capability of latex film was attributed to the reversible photodimerization of coumarin groups and multiple hydrogen bonds. In addition, the water-oil repellent and mechanical properties of the latex films were improved as the CMA and UPyMA monomer dosage increased.