Ultrafast Preparation Research Articles

Preparation and slow-release properties of nanocellulose composite hydrogels

Nanocellulose (CNF) was obtained from carrots using a combination of chemical treatment, mechanical milling, and ultrasonic treatment. Ultrafast preparation of maleic anhydride esterified nanocellulose was achieved by a hydrated hydrogen ion-driven dissociation, chemical cross-linking strategy based on a “one-pot” reaction method. Esterification modification with maleic anhydride reduced the crystallinity of nanocellulose and enhanced its thermal stability. High-strength drug-carrying hydrogels (MACNF/SA) with different drug loading capacities were prepared using cefixime (CFX) as a drug model and maleic anhydride esterified nanocellulose (MACNF) and sodium alginate (SA) as the main raw materials. The compressive strength of MACNF/SA hydrogels made from MACNF reached a maximum of 80.3 kPa when the mass ratio of CNF to MA was 2.5:12. Rheological property tests showed that the MACNF/SA hydrogels were pseudoplastic fluids with shear thinning. The drug release from the drug-carrying hydrogels followed non-Fickian diffusion.

Lignin sulfonate induced ultrafast fabrication of polypyrrole-based conductive organohydrogel for high performance flexible strain and temperature sensor

The ultrafast preparation of electrically conductive hydrogels to endow high sensing performance and temperature tolerance remains a critical challenge. Herein, lignosulfonate sodium-templated polypyrrole (LS-PPy) nanofillers were rapidly introduced into polyacrylic acid (PAA) hydrogel through ultrafast free radical polymerization in a glycerol/water binary solvent system. The resultant LS-PPy/PAA electrically conductive organohydrogel possesses satisfactory mechanical performance (strength of 56 kPa at a tensile strain of 800 %), strong adhesion, and a desirable low freezing point (−35 °C). Furthermore, this organohydrogel exhibits high strain sensitivity (gauge factor = 2.65), fast response time (~160 ms), low signal hysteresis, and excellent cyclic stability (over 1200 cycles). And the wearable LS-PPy/PAA organohydrogel sensor could accurately and real-time monitor various intense or subtle human movements, such as joint bending, facial expression and hand writing. Besides, the developed LS-PPy/PAA temperature sensor can respond to environmental temperature variations over a wide range of −20–100 °C. High resolution of 0.5 °C with remarkable sensitivity (−0.80 %/°C and linearity of R2 = 0.99) and repeatability were achieved within 36.5–40 °C, which makes it suitable for human body temperature monitoring. All these results demonstrate the substantial prospective value of the LS-PPy/PAA hydrogel in wearable sensors and other associated fields.

Ultrafast Preparation of Defective Nitrogen-Doped Carbon by Carbon Thermal Shock Method with Efficient Oxygen Reduction Reaction Activity for Zn-Air Battery

Ultrafast Preparation of Defective Nitrogen-Doped Carbon by Carbon Thermal Shock Method with Efficient Oxygen Reduction Reaction Activity for Zn-Air Battery

Sub-minute carbonization of polymer/carbon nanotube films by microwave induction heating for ultrafast preparation of hard carbon anodes for sodium-ion batteries

Hard carbons (HCs) are excellent anode materials for sodium-ion batteries (SIBs). However, the carbonization and granulation of HC powders involve complex processes and require considerable energy. Here, we developed a facile method for manufacturing HC anodes for SIBs via a novel microwave induction heating (MIH) process for polymer/single-walled carbon nanotube (SWCNT) films. Numerical simulations solving electromagnetic field and heat transfer problems revealed the MIH mechanism; the electric current induced by the applied microwave enables direct Joule heating of the SWCNT networks in the composite film. Consequently, the composite films could be heated to the target temperatures (800–1400 °C) and free-standing HC/SWCNT anodes could be prepared by applying MIH for only 30 s. Comparative analyses confirmed that ultrafast MIH is a reliable technique for producing HC anodes and can replace conventional carbonization processes which require a high-temperature furnace. Moreover, the HC/SWCNT anodes prepared by the ultrafast MIH were successfully applied to the SIB full cells. Finally, the feasibility of MIH for scalable roll-to-roll production of HC anodes was verified through local heating tests using a circular sheet larger than a resonator.

Ultra-fast preparation of UO2 fuel pellets by high pressure spark plasma sintering

A new sintering technique as a combination of ultra-fast spark plasma sintering and high-pressure sintering was employed to densify UO2 fuel pellets. UO2 pellets with a relative density of 97.5 % and inhibited grain growth were fabricated at 1000 °C under 150 MPa within only 4.5 min. Both short sintering time and high pressure might explain the inhibited grain growth and hence finer microstructures. UO2 fuel pellets prepared in this work exhibit excellent mechanical properties.

Ultra-Fast Preparation of High-Strength Polymer Concrete via Frontal Polymerization at Room Temperature.

Concrete, in particular application scenarios, such as crack repair, disaster rescue and relief, and 3D printing, needs to be cured quickly. In this work, a novel synthesis strategy, UV-initiated frontal polymerization (FP), for fast preparation of high-strength polymer concrete at room temperature is proposed, and the whole fabrication progress within several minutes, in which coarse aggregates and a small amount of short carbon fibers (CF) are used to enhance mechanical properties and heat conduction and reduce the amounts of chemical adhesives. SEM, DSC, MIP, Ultra depth of field microscope, and Rheometer are employed to characterize the properties of chemical adhesives, polymer concrete, and polymerization process. In addition, the finite element method is used to investigate the internal temperature field status of the FP process. The results indicate that the compressive and flexural strengths of the polymer concrete with 1.0wt%-1mm-CF-50vol.%-quartz sand exceeded 70 and 20MPa, respectively, in which the average self-propagation velocity reached 58mmmin-1. The investigation provides a promising approach for the rapid construction of structural facilities, emergency repair after disasters, 3D printing concrete, etc.

Ultrafast preparation of ruthenium nanoparticle/molybdenum oxide/nitrogen-doped carbon nanocomposites by magnetic induction heating for efficient hydrogen evolution reaction

Synergetic interactions between ruthenium and molybdenum oxide weaken H adsorption on ruthenium active sites and hence enhance the electrocatalytic activity towards hydrogen evolution reaction.

Ultrafast preparation and detection of entangled atoms.

Atoms can form a molecule by sharing their electrons in binding orbitals. These electrons are entangled. Is there a way to break a molecular bond and obtain atoms in their ground state that are spatially separated and still entangled? Here, we show that it is possible to prepare these spatially separated, entangled atoms on femtosecond time scales from single oxygen molecules. The two neutral atoms are entangled in the magnetic quantum number of their valence electrons. In a time-delayed probe step, we use nonadiabatic tunneling, which is a magnetic quantum number-sensitive ionization mechanism. We find a fingerprint of entanglement in the measured ionization probability as a function of the angle between the light's quantization axis and the molecular axis. This establishes a platform for further experiments that harness the time resolution of strong-field experiments to investigate spatially separated, entangled atoms on femtosecond time scales.

Role of the Coordination of Metal Ions by Ammonia for the Anodic Electrosynthesis of MOF Films

Metal-organic frameworks (MOFs), consisting of inorganic nodes coordinated by organic ligands, have received tremendous attention in the past decades due to their high surface area, high porosity, designable pore-aperture shape/size, and tunable building units (including metal centers and functional ligands). For most of their applications, such as separation, catalysis, sensors, and energy storage/conversion devices, MOFs in the form of films/membranes are desired. Anodic electrodeposition is a promising and cost-effective method to in-situ prepare metal-organic framework (MOF) films on metal substrates. However, the anodic synthesis of continuous zeolitic imidazolate framework (ZIF) films, an important subclass of MOF materials, has been proved challenging. Here, we report a facile anodic deposition method that enables the ultra-fast preparation of uniform and continuous ZIF-8 films with tunable thickness from the aqueous solution at room temperature by using the ammonia hydroxide-assisted deprotonation strategy (AHADS). The growth rate of the MOF films is flexibly controlled by the applied current densities, the concentration of the linkers, and the amount of added ammonia hydroxide. The roll-to-roll deposition of the ZIF-8 films on the zinc foils shows the possibility of this method for large-scale industrial synthesis. The control experiments and theoretical calculations reveal that the formation of Zn(NH3)4 2+ complex by adding excessive ammonia hydroxide is crucial to promote the coordination of 2-Methylimidazole (Hmim) with Zn2+. Afterward, the Zn2+ cation attracts electrons of Hmim and thus weakens the N-H bond, which decreases the free energy for the deprotonation of Hmim. As a result, the ZIF-8 films can be aqueously deposited at low pH under room temperature. Various pure ZIF films (ZIF-4, ZIF-7, and ZIF-67) with different metal nodes or organic linkers were successfully deposited via this strategy. In addition, ZIF-8 films deposited on the zinc foil show ability to decrease the overpotential for the zinc plating and stripping, suggesting its possibility for use in reversible zinc metal batteries. This work broadens the applicability of anodic deposition and indicates the potential applications of metal-supported MOF films in energy storage and conversion fields

Ultrafast Strategy to Fabricate Sulfur Cathodes for High-Performance Lithium-Sulfur Batteries.

Based on the different dielectric properties of materials and the selective heating property of microwaves, the ultrafast (30 s) preparation of S-NiS2@SP@Bitu as a cathode material for lithium-sulfur batteries was achieved using bitumen, sulfur, Super P, and nickel naphthenate as raw materials for the first time, under microwave treatment. NiS2@SP@Bitu forms Li-N, Li-O, Li-S, and Ni-S bonds with polysulfide, which contributes to promoting the adsorption of polysulfide, reducing the precipitation and decomposition energy barrier of Li2S, and accelerating the catalytic conversion of polysulfide, as result of inhibiting the "shuttle effect" and improving the electrochemical performance. S-NiS2@SP@Bitu as the sulfur cathode material demonstrates outstanding rate performance (518.6 mAh g-1 at 4C), and stable cycling performance. The lithium-sulfur battery with a sulfur loading of 4.8 mg cm-2 shows an areal capacity of 4.6 mAh cm-2. Based on the advantages of microwave selective and rapid heating, this method creatively realized that the sulfur carrier material was prepared and sulfur was fixed in it at the same time. Therefore, this method would have implications for the preparation of sulfur cathode materials.

Ultrafast microfluidic preparation of highly dispersed Ru/TiO2 catalyst for the hydrodeoxygenation of lignin-derived phenolic compounds

An ultrafast preparation method that coupled the photochemical method with the microfluidic technology to synthesize the highly dispersed Ru/TiO2 catalyst within only 1 min was proposed. This method had an enhanced electron excitation and a high electron transfer efficiency during the preparation process due to the small dimension of the microchannel, which enabled to shorten the preparation time greatly. Much higher metal reduction efficiency was obtained than that of the single photochemical method, and a high Ru metal dispersion on the TiO2 surface can be achieved. Moreover, a strong interaction between the metal site and the support was formed, resulting in more spillover hydrogen. This Ru/TiO2 catalyst presented a high activity on the HDO of phenolic compounds. Guaiacol was converted into cyclohexane with 97.6 % selectivity at 260 °C. The raw lignin-oil also can be upgraded efficiently, with the hydrocarbon content increased from 6.7 % to 69.4 %.

Ultra-fast synthesis and thermodynamic analysis of MoAlB by self-propagating high-temperature combustion synthesis

MoAlB as a typical member of MAB phases has attracted much-growing attention due to its unique properties. However, the low production of MoAlB powders limits its further development and potential applications. In the present work, the ultra-fast preparation of high-purity MoAlB powders in a few seconds is achieved by self-propagating high-temperature synthesis (SHS) using a raw powder mixture at an atomic ratio of Mo : Al : B = 1 : 1.3 : 1. SHS reaction mechanism is obtained by analyzing the corresponding composition changes of starting materials. Furthermore, the thermodynamic prediction for the SHS reaction is consistent with the present experiments, where the preparation of MoAlB also conforms to two common self-propagating conditions of the SHS. The enthalpy vs. temperature curve shows that the adiabatic temperature of the reaction decreases with the amount of excuse Al increasing but increases when pre-heating the reactants. Also, this thermodynamic calculation provides a new idea for the preparation of other MAB phases by the SHS.

Ultrafast synthesis of cobalt/carbon nanocomposites by magnetic induction heating for oxygen evolution reaction

Metal/carbon nanocomposites have shown great potential as high-performance, low-cost electrocatalysts owing largely to their unique metal-support interactions. These nanocomposites are typically prepared by conventional pyrolysis that is tedious and energy-intensive. Herein, we report the ultrafast preparation of cobalt/carbon nanocomposites by magnetic induction heating (MIH) of metal organic frameworks within seconds under an inert atmosphere. The resulting samples consist of cobalt nanoparticles encapsulated within defective carbon shells, and effectively catalyze oxygen evolution reaction (OER) in alkaline media. Among the series, the sample prepared at 400 A for 10 s exhibits the best OER performance, needing a low overpotential of +308 mV to reach the current density of 10 mA cm−2, along with excellent stability, and even outperforms commercial RuO2 at high overpotentials. This is ascribed to the charge transfer between the carbon scaffold and metal nanoparticles. Operando X-ray absorption spectroscopy measurements show that the electrochemically produced CoOOH species is responsible for the high electrocatalytic performance. The results highlight the unique potential of MIH in the development of effective nanocomposite catalysts for electrochemical energy technologies.

Ultrafast and continuous synthesis of phase change nanocapsules using salt-accelerated microwave-assisted polymerization

Using a microwave-assisted polymerization method for the continuous and ultrafast preparation of nanoencapsulated phase change materials (NanoPCMs) for energy storage.

Ultrafast preparation of NiFe nanocluster/graphene heterojunction catalysts for oxygen evolution reaction and urea oxidation reaction

Developing low-cost and highly efficient oxygen evolution reaction (OER) and urea oxidation reaction (UOR) electrocatalysts is critically important for hydrogen production through electrochemical water splitting.

Ultrafast Preparation of Metal/Carbon Nanocomposite Electrocatalysts by Magnetic Induction Heating toward Efficient Hydrogen Evolution Reaction

Hydrogen, which can be readily produced by electrochemical water splitting, has been hailed as one of the most promising green energy sources. In a water electrolyzer, catalysts are needed for the hydrogen evolution reaction (HER) at the cathode, which are traditionally based on platinum-based materials. Recently, carbon-based nanocomposites have emerged as viable alternatives, which are mostly prepared by pyrolysis or wet chemistry methods, which are time- and energy-consuming. We have exploited magnetic induction heating (MIH) for ultrafast and green preparation of high-performance HER electrocatalysts. A novel MIH method was developed for the ultrafast and green preparation of carbon-supported Ru NPs toward HER in alkaline media, where the size and morphology of the Ru NPs can be readily manipulated by the heating current and duration. It is expected that MIH can be exploited for the design and engineering of high-performance nanocomposite catalysts for important electrochemical energy technologies.

Ultrafast preparation of amorphous hydroxide on 3D carbon cloth for efficient oxygen evolution reaction

Ultrafast preparation of amorphous hydroxide on 3D carbon cloth for efficient oxygen evolution reaction

Ultrafast Synthesis of Layered Transition-Metal Oxide Cathodes from Metal-Organic Frameworks for High-Capacity Sodium-Ion Batteries.

Layered transition-metal oxides are promising candidate cathode materials for sodium-ion batteries due to their abundant raw materials and high theoretical capacity. Nevertheless, a long-time high-temperature heat treatment is required in traditional preparation methods, leading to low synthesis efficiency and waste of energy. Herein, an ultrafast preparation method of layered transition-metal oxides was proposed through minute calcination of metal-organic frameworks (MOFs). The homogeneous distribution of different atoms in MOFs allows fast phase transition during the calcination process. P'2-phase layered sodium manganese oxide was successfully obtained and demonstrated excellent electrochemical performance, with a high reversible capacity of 212 mA h g-1 and a cycling performance of 84% capacity retention after 100 cycles. Furthermore, this method can be expanded to a wide variety of MOF precursors and oxide electrode materials for different types of batteries. Our findings provide an efficient and cost-effective synthesis method for high-performance layered transition-metal oxide cathodes.

Redox-activity of polydopamine for ultrafast preparation of self-healing and adhesive hydrogels

The high adhesive property of polydopamine (PDA) has spurred various hydrogels for biological and medical applications. Herein, a dual-catalytic redox system was constructed by using the inner dynamic redox-activity of PDA and free radical initiator ammonium persulfate (APS) to initiate the polymerization of acrylic acid (AA) monomer to obtain Fe-PDA hydrogels within 2 h at room temperature. Fe-PDA NPs functions as both initiator to activate APS to generate free radicals and promotes the formation of the hydrogel and dynamic cross-linking mediator between the polymer chains. The tensile strength and ductility of the obtained hydrogels vary with the content of Fe-PDA NPs. Hydrogel with 0.15 wt% of Fe-PDA NPs has the highest tensile strength (~0.62 MPa) and hydrogel with 0.6 wt% of Fe-PDA NPs has the highest elongation, about ~650%. The introduction of PDA NPs imparts PAA hydrogel with reproducible adhesive properties and self-healing ability. The doped iron ion further endows hydrogel enhanced photothermal properties (up to 160 ℃ with 808 nm laser irradiation for 120 s) and conductivity.

Ultra-fast preparation of multifunctional conductive hydrogels with high mechanical strength, self-healing and self-adhesive properties based on Tara Tannin-Fe3+ dynamic redox system for strain sensors applications

Flexible wearable devices are drawing a lot of interest from researchers because of their enormous potential for applications in human-computer interaction, e-skin and disease diagnosis. In particular, hydrogel-based flexible electronic devices with good bio-friendliness, excellent mechanical properties (tensile and compressive), self-adhesion, self-healing, and high electrical conductivity are the hot topics of research. Herein, we built up a dynamic redox system using Tara tannin and Fe3+ combined with the Fenton reaction to prepare a multifunctional conductive dual-network interpenetrating hydrogel (Tara-Fe3+-PAA-CSMA), which was fast prepared (1–5 min), low-cost and energy saving (reaction at room temperature). Poly(acrylic acid) (PAA) formed the first layer of the network and CSMA (chitosan modified by methacrylic acid) constructed the second layer. The obtained hydrogel has high transmittance and strong UV absorption, excellent tensile properties (900%, 0.75 MPa) and adhesion to a wide range of materials (metals, wood, skin, plastic, etc.). Meanwhile, its good self-healing ability, reliable conductivity and high sensitivity (GF = 5.33, 80% tensile strain) provided the possibility for its application as a conductive strain sensor. The hydrogel sensor can accurately capture several motion signals, such as walking, arm shaking and swallowing. What's more, it can also sharply monitor the vibration of the larynx during vocalization and distinguish different sound information according to the graph obtained. In summary, this work innovatively proposed a Tara tannin-Fe3+ based dynamic redox system that makes it possible to quickly prepare conductive hydrogels at room temperature. It is expected to advance the industrial production of wearable flexible electronic devices.