One-pot Polymerization Research Articles

Vertically Expanded Covalent Organic Frameworks for Photocatalytic Water Oxidation into Oxygen.

Covalent organic frameworks with unique π architectures and pores could be developed as photocatalysts for transformations. However, they usually form π-stacking layers, so that only surface layers function in photocatalysis. Here we report a strategy for developing vertically expanded frameworks to expose originally inaccessible active sites hidden in layers to catalysis. We designed covalently linked two-dimensional cobalt(II) porphyrin layers and explored coordination bonds to connect the cobalt(II) porphyrin layers with bidentate ligands via a three-component one-pot polymerization. The frameworks expand the interlayer space greatly, where both the up and down faces of each cobalt(II) porphyrin layer are exposed to reactants. Unexpectedly, the vertically expanded frameworks increase skeleton oxidation potentials, decrease exciton dissociation energy, improve pore hydrophilicity and affinity to water, and facilitate water delivery. Remarkably, these positive effects work collectively in the photocatalysis of water oxidation into oxygen, with an oxygen production rate of 1155 µmol g-1 h-1, a quantum efficiency of 1.24% at 450 nm, and a turnover frequency of 1.39 h-1, which is even 5.1-fold as high as that of the π-stacked frameworks and ranks them the most effective photocatalysts. This strategy offers a new platform for designing layer frameworks to build various catalytic systems for chemical transformations.

Rational design of alginate-derived network binder for high-performance silicon-based anodes in Li-ion batteries

This study developed a novel alginate-derived network binder, SAH, to enhance the performance and stability of silicon-based anodes in lithium-ion batteries. Integrating acrylic acid and 2-hydroxyethyl acrylate with sodium alginate through a one-pot polymerization and in-situ cross-linking method, SAH effectively addresses the volumetric expansion challenges associated with silicon anodes. This innovative binder maintains the structural integrity of the silicon anode through its rigid acrylic acid component, while the flexible acrylic-2-hydroxyethyl ester serves as a dynamic buffer to enhance flexibility. Sodium alginate contributes its intrinsic beneficial properties and imparts a robust three-dimensional network structure through effective coupling, allowing the binder to accommodate silicon volume changes during battery operation. Consequently, lithium-ion batteries incorporating this binder exhibited improved stability and extended cycle life, achieving an impressive capacity retention rate of 87.3 % after 100 cycles at 0.5C. This study highlights the potential of biopolymeric materials in enhancing the functionality of silicon-based anodes, contributing to the ongoing development of high-performance energy storage technologies.

Ternary polymeric beads of chitosan-based polyaniline doped iron oxide used for removal of cadmium and lead ions from water: Kinetic, isotherm and mechanism studies

ABSTRACT In this study, the binary polymeric magnetic beads were synthesized successfully by one-pot polymerization of polyaniline (PA) doped magnetic iron oxide nanoparticles (MNPs) followed by chitosan (CTS) cross-linkage. The newly fabricated ternary magnetic beads (CTS@MPA) were applied to enhance the removal of Pb(II) and Cd(II) ions from the aqueous media. The prepared nanocomposite was characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometry (VSM). Adsorption experiments were carried out under optimum conditions. To evaluate the experimental data, the isotherm and kinetic models were conducted. The behavior of adsorption was assessed, and the coefficient of determination values demonstrated that the adsorption process best fitted the Freundlich model due to high values of R2 (0.957 & 0.981). The maximum adsorption capacity was obtained at 150.82 mg.g−1 and 169.21 mg.g−1 for Pb(II) and Cd(II) ions, respectively. Kinetic studies showed that adsorption follows a pseudo-second-order model (R2 = 0.952 & 0.985). Weber-Morris claims that intraparticle diffusion plays a significant role in the adsorption kinetics. Finally, the thermodynamic study is demonstrated, and the adsorption is endothermic, and the mechanism follows a physisorption pattern.

Fabrication of Vanadium Oxide-encapsulated Hybrid Carbon Nanospheres for Enhanced Tribological Performance.

A new sulfur-containing carbon nanospheres encapsulated with vanadium oxide (V@SCN) is synthesized through a one-pot oxidation polymerization and then carbonization method. The prepared V@SCNs exhibit good dispersibility as a lubricant additive, which is owing to the inherited lipophilic organic functional groups in the sulfur-containing carbon shell derived from the carbonization of polythiophene. The agglomeration and precipitation of metals in the base oil are also avoided through the encapsulation of lipophilic carbon shells. The stress and thermal simulation results show that the vanadium oxide core bestows upon the carbon nanospheres enhanced load resistance and superior thermal conductivity, which contributes to their excellent tribological properties. Introducing 0.04M-V@SCN to the base oil leads to favorable tribological characteristics, such as a fourfold rise in extreme pressure capacity from 250 to 1050N, a reduction in friction coefficient from 0.2 to ≈0.1, and a substantial decrease in wear by 90.2%. The lubrication mechanism of V@SCNs as lubricant additive involves the formation of a robust protective film on the friction pair, which is formed via complex physical and chemical reactions with the friction pair during friction.

One-Pot Fabrication of Kinetically Inert Ultrasmall Manganese(II) Chelate-Backboned Polymer Contrast Agents for High-Performance Magnetic Resonance Imaging.

Traditional macromolecules or nanoscale Mn2+ chelate-based magnetic resonance imaging (MRI) contrast agents (CAs) suffer from complicated and laborious synthesis processes, relatively low kinetic stability and T1 relaxivity, limiting their clinical applications. Herein, we fabricated a series of kinetically inert Mn2+ chelate-backboned polymers, P(MnL-PEG), through a facile and one-pot polymerization process. Particularly, P(MnL-PEG)-3 demonstrates a significantly higher T1 relaxivity of 23.9 Mn mM-1 s-1 at 1.5 T than that of previously reported small molecules and macromolecules or nanoscale Mn2+ chelate-based CAs. Due to its high T1 relaxivity, extended blood circulation, hepatocyte-specific uptake, and kidneys metabolism, P(MnL-PEG)-3 presents significantly enhanced contrast in blood vessel, liver, and kidneys imaging compared to clinical Gd3+-based CAs (Gd-EOB-DTPA and Gd-DOTA) at a dosage of 0.05 mmol Mn/Gd kg-1 BW, and can accurately diagnose orthotopic H22 liver tumors in vivo in animal models. We anticipate that this work will promote the development of clinically relevant MRI CAs.

A one-pot strategy for modifying the surface of Ti3C2Tx MXene

Surface modification of MXenes significantly expands their potential for a wide range of applications. Here, we demonstrate a one-pot spontaneous polymerization of acrylic acid onto MXene sheet surfaces using an aryl diazonium coupling agent (nitrobenzene diazonium salt) as an approach to tune MXene interfacial properties. We use this formation of polymer coatings as a coagulation strategy for spinning fibers from liquid crystal MXene dispersions, obtaining densified free-standing fibers with tensile strength and breaking energy of ~155 MPa and ~4.5 MJ m−3. This simple method potentially offers a scalable approach for fabricating functional MXene macroarchitectures.

Capacitive behaviors for surface-sulfonated polyaniline nanofibers in different acidic electrolytes

Abstract Unique surface-sulfonated polyaniline nanofibers (PANI-S) were fabricated through one-pot polymerization to evaluate the feasibility of their applications as electrode materials for high-performance supercapacitors that can be operated in relatively weak acidic electrolytes. Benefiting from the self-doping effect and improved dispersion in aqueous solution for the nanofibers, as well as the effective buffering function of the electrolyte, the PANI-S exhibits excellent capacitive performance across a broad pH value range in acidic electrolytes. More clearly, the specific capacitance of the PANI-S remains remarkably stable, ranging from 752.4 to 754.4 F g−1 at a scan rate of 5 mV s−1 and from 575.4 to 536.8 F g−1 at a current density of 1 A g−1, as the pH value of the electrolyte varies from 0 to 6. However, the capacity retention rate of PANI-S gradually decreases from 79.2% to 37.2% as the current density increases from 1 A g−1 to 20 A g−1, with the pH of the buffered solution increasing from 0 to 6. The excellent electrochemical activity in low acidic electrolytes for PANI nanofibers can be attributed to the compensation effects of the self-doped local proton reservoir.

MXene-based self-adhesive, ultrasensitive, highly tough flexible hydrogel pressure sensors for motion monitoring and robotic tactile sensing

With the rapid development of artificial intelligence and human–computer interaction fields, wearable electronic devices represented by flexible pressure sensors have a wider range of application scenarios. In this paper, we used a composite hydrogel made by one-pot polymerization using a combination of acrylamide (AM), sodium carboxymethyl cellulose (CMC), dopamine (DA), and MXene (Ti3C2Tx). The composite hydrogel has the advantages of self-adhesion, high sensitivity, large detection range (0–500 kPa), low detection limit, high toughness (compression > 90 %), stability (more than 6700 s) and other advantages of hydrogel flexible pressure strain sensor. Sodium carboxymethyl cellulose (CMC), as a multifunctional thickener and gelling agent, significantly improves rheological properties and viscosity in hydrogels, forms crosslinked structures to enhance mechanical properties and provides reliable toughness for pressure sensors. Dopamine (DA), which is rich in catechol groups, can adhere to the material surface through oxidative polymerization to enhance bond strength. Hydrogel pressure sensors for human motion detection can accurately track joint movement, respond sensitively to changes in knocks and touches, and display specific characters such as Morse code. The technology extends to robotic systems, where pressure-activated electrical signals are used to control robot movements. Therefore, it has a very promising application in the field of human–computer interaction, human-body movement signal detection, etc. PAM/CMC/DA/MXene hydrogel pressure sensors have excellent mechanical, electrical, and adhesion properties, which provide a more reliable solution for the fields of flexible wearable e-skin, human–computer interaction, and tactile sensing.

Efficient generation of 1O2 by activating peroxymonosulfate on graphitic carbon nanoribbons for water remediation

Few-layer graphitic carbon nanoribbons (GCN) with rich defective sites were prepared by pyrolysis at 800 oC in N2 of in situ-chelated Fe-polyaniline complexes synthesized via one-pot homogeneous Fenton-like oxidative polymerization of an acidic aniline solution. A minimal amount of iron (0.47 wt%) made a pivotal role in the nanoribbon growth and graphitization of GCN, and deposited highly dispersed iron species on GCN without post-synthesis acid leaching, which greatly simplified the synthesis procedure of GCN with improved yield. GCN exhibited high activity and stability for catalytic degradation of organic pollutants with peroxymonosulfate (PMS) mainly via non-radical pathways. The influences of various operating parameters on the catalytic performance of GCN were investigated. Scavenging tests, spin-trapping electron paramagnetic resonance spectra, electrochemical analyses, and theoretical calculations unveiled that 1O2 was the main reactive oxygen species generated from synergistic activation of PMS on GCN while GCN-mediated electron transfer made a minor contribution to organic degradation.

Bentonite clay reinforced alginate grafted composite hydrogel with remarkable sorptive performance toward removal of methylene green

The rapid industrial progress in today's world has led to an alarming increase in water pollution caused by various contaminants such as synthetic dyes. To address this issue, a new hydrogel sorbent, BC-r-Na-Alg-g-p(NIPAm-co-AAc), was developed by combining bentonite clay, sodium alginate, and poly(N-isopropyl acrylamide-co-acrylic acid) through one-pot free radical polymerization at 60 °C. The developed sorbent was characterized using several analytical techniques including SEM, FTIR, TGA, UTM, and swelling studies. The swelling capacity of the sorbent was observed to increase remarkably with an increase in pH, reaching a maximum of 9664 % at pH 11. In batch mode sorption experiments, the sorbent's performance toward methylene green (MG) was investigated by analysing the effects of contact time, pH, temperature, and concentration. The experimental data were fitted to pseudo-second-order kinetic and Langmuir isotherm models, indicating chemisorption as the dominant interaction mode between the anionic sorbent and cationic MG. However, physisorption may also occur to a lesser extent, indicated by the significant R2 of the pseudo-first-order kinetic and Freundlich isotherm models. Additionally, the sorbent exhibited very little decrease (approximately 5 %) in sorptive performance for six sorption-desorption cycles. Overall, the facile fabrication, excellent swelling (9664 %), promising sorption performance (2573 mg.g−1), and good recyclability (6 cycles) make the developed sorbent a potential candidate for various industrial applications.

Nonconjugated Polyurethane Derivatives with Aggregation-Induced Luminochromism for Multicolor and White Photoluminescent Films.

A simple and effective strategy to obtain solid-state multicolor emitting materials is a particularly attractive topic. Nonconventional/nonconjugated polymers are receiving widespread attention because of their advantages of rich structural diversity, low cost, and good processability. However, it is difficult to control the molecular conformation or to obtain the crystal structure of amorphous molecules, which means it is a challenge to obtain nontraditional polymeric materials with multicolor emission. In this work, a polyurethane derivative (PUH) with red-shifted emission was synthesized by a simple one-pot polymerization reaction. By exploiting the aggregation-induced luminochromism of PUH, a series of plastic films with tunable emission from blue to orange, and white-light emission, was obtained by doping different amounts of PUH into poly(methyl methacrylate) (PMMA), thereby changing the aggregation degree of PUH. This work demonstrates the excellent promise of polyurethane derivatives for the simple fabrication of large-scale flexible luminescent films.

The robustness waterproof ionogel based on the phase separation to form soft hard heterostructures and the interaction of cation-π realizes underwater adhesion and sensing

Flexible ionic conductors hold significant promise for advancing the field of soft ion electronics in the future. However, the creation of flexible conductors that possess mechanical robustness, underwater adhesion and underwater motion monitoring remains a challenge. Drawing inspiration from the multiphase hetero structure found in biological connective tissues, such as high modulus fibers and low modulus water-rich matrices, this article proposes a one-pot polymerization in-situ design strategy to create a hydrophobic ionogel with a hetero structure of soft and hard domains. The mechanical robustness, elasticity, and toughness of the ionogel are achieved through a synergistic combination of a strong skeleton in the hard domain and an elastic matrix in the soft domain. Additionally,hydrophobic aromatic rings and quaternary ammonium cation simulated cation-π interactions in mussel foot silk protein. Upon contact with water, the hydrophobic clusters quickly aggregate, facilitating the expulsion of interfacial water and exposing salicylic acid groups and quaternary ammonium cationic groups, leading to outstanding underwater adhesion between the ionogel and various substrates. The resulting hydrophobic ionogel can be utilized in underwater wearable electronic devices for monitoring human movement and physiological information, underwater repair monitoring, and intelligent soft robotics, demonstrating its vast potential in the field of underwater sensors.

In-situ halloysite functionalization of anionic hybrid gels possessing easily implemented site-specific (alkyl)amide and carboxyl groups

Design of functional materials with tunable properties based on anionically-modified copolymer network of poly (N-isopropyl acrylamide-co-methacrylic acid) P(NIPA-co-MA) containing linear polyacrylamide and various amounts of Halloysite nanotubes (Hal) was presented using a facile route of solution casting. The organic/inorganic nanostructures based on thermo-responsive PNIPA were constructed to create hybrid materials via in situ polymerization with different Hal-loading and then used for the removal of cationic methylene blue (MB) dye from aqueous solutions. To achieve the desired mechanical property, the optimum composition of hybrids was determined following a simple and cost-effective synthesis procedure. In situ one-pot polymerization was promoted by semi-IPN formation, following a much simpler route than traditional preparation approaches for stable cross-linked hybrid formation. The swelling of hybrids decreased by 2.9-fold with loading of 5.40 % Hal, confirming the hydrogen bonding interactions between Hal and PAAm/P(NIPA-co-MA) network. The mechanical properties of Hal-doped hybrid gels showed an increase–decrease tendency with increase of Hal-content from 0.80 to 5.40 % (w/v) due to the high aspect ratio of Hal and strong secondary interactions between Hal and PAAm/P(NIPA-co-MA) chains. The effective cross-link density for Hal-doped hybrids was expressed by a cubic polynomial as a function of Hal concentration. Temperature-sensitive swelling results showed that the advantage of sustained release property of Hal can be combined with excellent controllability of PNIPA-based network. Adsorption results of MB onto Hal-doped hybrids bearing methacrylic acid moieties demonstrated their potential as efficient adsorbents for the removal of cationic dyes. A new route offered by the proposed procedure for design of hybrids containing “green” one-dimensional nanofillers creates an innovative perspective on robust hybrid structures for practical applications.

A Nanofibrous Polypyrrole Membrane with an Ultrahigh Areal Specific Capacitance and Improved Energy and Power Densities.

For conductive polymers to be competitive with carbon-based electrode materials, it is critical to increase their surface area and electroactivity. In this work, a thick nanofibrous polypyrrole (PPy) membrane with communicating interfiber spaces was prepared through one-pot interfacial polymerization for the first time. The electrochemical properties and conductivity of the membrane were studied with cyclic voltammetry, electrochemical impedance spectroscopy, and a four-point probe. Its morphology, chemistry, and thermostability were evaluated by scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The areal specific capacitances measured between 0.0 and 0.8 V at 1 mA/cm2 were 19179, 13264, 7238, and 4458 mF/cm2 for the membranes doped with docusate sodium (AOT), camphor-10-sulfonic acid (β) (CSA), Cl-, and poly(sodium 4-styrenesulfonate) (PSS), respectively. The capacity retentions after 1000 cycles were 83, 74, 67, and 61% for the AOT-, CSA-, PSS-, and Cl--doped membranes, respectively. The Coulombic efficiency was above 99% for all of the membranes. They showed energy densities of 1.7, 1.2, 0.7, and 0.4 mWh/cm2 and power densities of 0.61, 0.75, 0.66, and 0.62 mW/cm2 for the AOT-, CSA-, Cl--, and PSS-doped membranes, respectively. The ultrahigh areal specific capacitance of PPy-AOT is due to its nanofibrous structure. A mechanism has been proposed to explain how this structure is formed based on the role of AOT as the surfactant. This nanofibrous PPy membrane is easy to prepare and metal-free and offers a very high areal specific capacitance, making it an excellent candidate to construct electrodes in pseudosupercapacitors.

Dual-Temperature/pH-Sensitive Hydrogels with Excellent Strength and Toughness Crosslinked Using Three Crosslinking Methods.

Hydrogels are widely used as excellent drug carriers in the field of biomedicine. However, their application in medicine is limited by their poor mechanical properties and softness. To improve the mechanical properties of hydrogels, a novel triple-network amphiphilic hydrogel with three overlapping crosslinking methods using a one-pot free-radical polymerization was synthesized in this study. Temperature-sensitive and pH-sensitive monomers were incorporated into the hydrogel to confer stimulus responsiveness, making the hydrogel stimuli-responsive. The successful synthesis of the hydrogel was confirmed using techniques, such as proton nuclear magnetic resonance spectroscopy (1H NMR), Fourier-transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). In order to compare and analyze the properties of physically crosslinked hydrogels, physically-chemically double-crosslinked hydrogels, and physically-chemically clicked triple-crosslinked hydrogels, various tests were conducted on the gels' morphology, swelling behavior, thermal stability, mechanical properties, and drug loading capacity. The results indicate that the triple-crosslinked hydrogel maintains low swelling, high mechanical strength, and good thermal stability while not significantly compromising its drug delivery capability.

Ultra-adherable dual-network conductive hydrogel with moistening and anti-freezing as a flexible sensor

Multifunctional conductive hydrogels have shown great promise in wearable flexible sensor application. This paper reported a dual-network self-healing electrically hydrogel through simple one-pot polymerization, which initiated from Ag+- lignin nanoparticles (LNPs) -APS redox system. Owing to the reversible metal coordination and hydrogen bonding cross-linked among polymer network, the resulting conductive hydrogel-based sensor demonstrated excellent stretchable, adhesion strength, and fatigue resistance. Additionally, the complex hydrogel (PHEMA/SA/Gly/Ca) incorporating with glycerol and CaCl2 in particular exhibited strong frost resistance (−40oC) and moisturizing qualities to monitor the motion signals in the low-temperature dry state. Therefore, the fabricated wearable sensor is sufficient for detecting large and small human motions, suggesting lots of promising applications in electronic skins, information identification and encryption, and human-motion monitoring.

Improving Zn2+ migration via designing multiple zincophilic polymer electrolyte for advanced aqueous zinc ion batteries

Aqueous zinc ion batteries (AZIBs)-based on Zn metal anode face serious issues of hydrogen evolution, corrosion, and zinc dendrite growth, limiting their practical applications. Polymer-based electrolytes can effectively inhibit the above issue, but usually bring additional interfacial resistance, resulting in slow reaction kinetics. Herein, we report a poly(4-acryloylmorpholine) electrolyte with multiple zincophilic primitives for fast zinc ion transport at bulk and interface of Zn metal anode (zinc ion transfer number of 0.77) via a facile one-pot polymerization. The special electrolyte structure with multiple zincophilic primitives can adhere tightly to the Zn metal anode and induce uniform Zn deposition, resulting in low interface resistance and enhanced cycling life of batteries. Therefore, the symmetric Zn||Zn batteries assembled based on the designed and synthesized polymer electrolyte can be stably cycled for 1400 with low overpotential (∼220 mV) at 0.5 mA cm−2 with a capacity of 0.5 mAh cm−2, and the corresponding V2O5||Zn full batteries exhibit attractive reversibility, rate performance, and cycling stability. The electrolyte engineering in this work paves a new path for the construction of polymer-based electrolytes for safe and stable AZIBs.

Direct and specific detection of methyl-paraoxon using a highly sensitive fluorescence strategy combined with phosphatase-like nanozyme and molecularly imprinted polymer

Methyl paraoxon (MP) is a highly toxic, efficient and broad-spectrum organophosphorus pesticide, which poses significant risks to ecological environment and human health. Many detection methods for MP are based on the enzyme catalytic or inhibition effect. But natural biological enzymes are relatively expensive and easy to be inactivated with a short service life. As a unique tool of nanotechnology with enzyme-like characteristics, nanozyme has attracted increasing concern. However, a large proportion of nanozymes lack the intrinsic specificity, becoming a main barrier of constraining their use in biochemical analysis. Here, we use a one-pot reverse microemulsion polymerization combine the gold nanoclusters (AuNCs) with molecularly imprinted polymers (MIPs), polydopamine (PDA) and hollow CeO2 nanospheres to synthesize the bright red-orange fluorescence probe (CeO2@PDA@AuNCs-MIPs) with high phosphatase-like activity for selective detection of MP. The hollow structure possesses a specific surface area and porous matrix, which not only increases the exposure of active sites but also enhances the efficiency of mass and electron transport. Consequently, this structure significantly enhances the catalytic activity by reducing transport distances. The introduced MIPs provide the specific recognition sites for MP. And Ce (III) can excite aggregation induced emission of AuNCs and enhance the fluorescent signal. The absolute fluorescence quantum yield (FLQY) of CeO2@PDA@AuNCs-MIPs (1.41 %) was 12.8-fold higher than that of the GSH-AuNCs (0.11 %). With the presence of MP, Ce (IV)/Ce (III) species serve as the active sites to polarize and hydrolyze phosphate bonds to generate p-nitrophenol (p-NP), which can quench the fluorescent signal through the inner-filter effect. The as-prepared CeO2@PDA@AuNCs-MIPs nanozyme-based fluorescence method for MP detection displayed superior analytical performances with wide linearities range of 0.45–125 nM and the detection limit of 0.15 nM. Furthermore, the designed method offers satisfactory practical application ability. The developed method is simple and effective for the in-field detection.

Ultrahigh temperature ablation resistant HfB2-SiC composites: From liquid SiHfCB precursor synthesis to light weight bulk preparation and characterization

The current generation of ultrahigh temperature ceramic precursors typically encounters obstacles in achieving high ceramic yields (<40 wt.%) due to the challenges in integrating significant amounts of boron, which hampers their conversion into boride-based ultrahigh temperature ceramics. To tackle these challenges, a serious of pioneering liquid multi-component hafnium-containing ceramic SiHfCB precursors (with different Hf/Si ratios) have been developed. These novel precursors are featured with stable molecular structure and high ceramic yield which were successfully created through a novel one-pot polymerization process. They present in liquid form and their structure is characterized by C-C bonds forming its main chain with branched chains of O-Si-O, Si-O-Hf, Si-O-B, and B-O-Hf which have untapped advantages including uniform component dispersion, and excellent fluidity. The ceramic yield of SiHfCB precursor with Hf/Si of 0.2 is remarkably up to 68.6 wt.% at 1500 °C, and their Hf content exceeded 50 wt.%. Of particular interest, the pyrolyzed product HfB2-SiC nanopowders derived from the SiHfCB precursor with Hf/Si of 0.2, consist of nanopowders in the 40–60 nm range with a density of 5.23 g cm−3. Remarkably, this material demonstrates exceptional performance in ultrahigh temperature oxygen-containing environments at 2500 °C, showing near-zero ablation with a linear ablation rate of just 2.5 × 10−4 mm s−1. Post-ablation analysis of the microstructure reveals that the formation of a lava-like HfO2 and HfO2-SiO2 oxide layer effectively blocks oxygen penetration and provides excellent oxidation resistance. The innovative SiHfCB hafnium-containing ceramic precursor offers a groundbreaking solution for the preparation of lightweight ultrahigh-temperature ceramics. This development is poised to provide robust technical support for the use of ultrahigh temperature ceramics in non-ablative thermal protective systems, particularly in the construction of hypersonic vehicles, where ultrahigh temperature resilience is crucial.

Low-Surface-Area Nitrogen-Doped Carbon Submicrospheres as High-Coulombic-Efficiency and High-Capacity Anodes for Practical Sodium-Ion Batteries.

Nitrogen-doped carbon submicrospheres (NCSMs) are synthesized via an efficient and environmentally friendly one-pot polymerization reaction at room temperature, in which dopamine hydrochloride serves as the source for both carbon and nitrogen. Through leverage of its distinctive structure characterized by minimal surface area, fewer oxygen-containing functional groups, and a heightened presence of active nitrogen-doping sites, the synthesized NCSM showcases a noteworthy initial Coulombic efficiency (ICE) of 84.8%, a remarkable sodium storage capacity of 384 mAh g-1, an impressive rate capability of 215 mAh g-1 at 10 A g-1, and a superior cyclic performance, maintaining 83.0% of its capacity after 2000 cycles. The submicron spherical structure, with its limited surface area and scarce oxygen-containing moieties, effectively curtails the irreversible sodium-ion loss in solid-electrolyte interphase film formation, resulting in heightened ICE. The abundant nitrogen doping can expand carbon-layer spacing as well as improve the electron/ion-transport dynamics, guaranteeing a high sodium storage capacity and a strong rate capability. Crucially, the synthesis method presented here is straightforward, effective, and amenable to scaling, offering a novel avenue for the commercialization of sodium-ion batteries.