Materials Horizons最新文献

The appearance of carbon spheres, chemical nanostructures, and physical spheres on the surface of carbon wires demonstrates the ability to overcome the optical weaknesses of carbon wires. Carbon dots (CDs) present far superior advantages over these structures in terms of excellent optical properties, and the transfer of these advantages from CDs to carbon wires would improve the specificity of the optical properties of carbon wires, but has been challenging to date. Here, a novel strategy for the fabrication of CDs on nanoconvex carbon wires is developed by pre-treating a Si substrate with oxidation and nitrogen, depositing nanoconvex PAN wires on the pre-treated Si substrate with electro-hydrodynamic jetting, and subsequently implementing stabilization and carbonization. We find that this strategy exhibits the unexpected ability to form CDs on nanoconvex carbon wires and transform these CDs from being dispersed to being connected together by control over both their quantity and dispersion. Our results demonstrate the presence of two types of CDs - wire-broken CDs and continuous carbon-wire-surfaced CDs. The ability of the carbon wires based on these new CDs to show outstanding optical signals in Raman and X-ray photoelectron spectroscopy spectra, creates an opportunity for research into novel physics and optical devices that have not previously been possible.

Sufficient mechanical performance is the basic requirement for load-bearing and damage-resistant materials. However, the simultaneous optimization of mechanical properties is usually difficult in a single hydrogel. Herein, a supersaturated salt was employed to enhance the mechanical performance and damage resistance of hydrogels. By immersing the pre-formed hydrogel based on hydrophobic associations into supersaturated Na₂SO₄ solution (3.3 M), high-density and strong hydrophobic associations were constructed simultaneously in the network due to the contraction of hydrophilic chains and improvement of hydrophobic associations. Compared to the pristine hydrogel, this salt-treated hydrogel was transparent and showed a simultaneous enhancement in stiffness (E of 253 ± 7 MPa), strength (σ of 12.65 ± 0.07 MPa), and toughness (Γ of 19.6 ± 3.2 MJ m^-3). It also displayed remarkable puncture and tear resistance with a puncture force of 66 N, a puncture energy of 370 mJ, and a tearing energy of 34 kJ m^-2. This work provides a simple method to simultaneously optimize the contradictory mechanical properties and puncture resistance in a single hydrogel.

Highly adaptable upcycling of waste polyolefins was demonstrated to obtain high-value nitro-containing polycarboxylic acids in high carbon yields. This method is applicable to a wide range of polyolefins, mixed PP/PE in any ratio, as well as actual polyolefin products and their mixtures. Moreover, the obtained products are homogenized with similarity in molecular weight and functional groups, enabling direct reutilization as fine chemicals or feedstocks for preparation of recyclable high-performance/functional materials. This work provided a new universal and efficient upcycling strategy for waste polyolefins, which may reshape the model of waste plastics recycling, while providing alternative functional chemicals and materials to achieve sustainable development.

In ferroelectric materials, an electric field has been shown to change the phonon dispersion sufficiently to alter the lattice thermal conductivity, opening the possibility that a heat gradient could drive a polarization flux, and technologically, also opening a pathway towards voltage-driven, all solid-state heat switching. In this report, we confirm the validity of the theory originally developed for Pb(Zr,Ti)O₃ (PZT) on the ferroelectric relaxor 0.67Pb[Mg_1/3Nb_2/3]O₃-0.33PbTiO₃ (PMN-33PT). In theory, the change in sound velocity and thermal conductivity with an electric field relates to the piezoelectric coefficients and the Grüneisen parameter. It predicts that in PMN-33PT the effect should be an order of magnitude larger and of opposite sign as in PZT; this is confirmed here experimentally. The effects are measured on samples never poled before and on samples that underwent multiple field sweep cycles and passed through two phase transitions with change in temperature. The thermal conductivity changes are linked to variations in the piezoelectric coefficients and can be as large as 8-11% at T ≥ 300 K. To date, this has been the only means of heat conduction modulation that utilizes changes in the phonon spectrum. While this technology is in its infancy, it offers another path to future active thermal conduction control.

As silicon-based technologies approach their physical limits, the search for alternative computing paradigms becomes imperative. Molecular logic has emerged as a promising approach, particularly the systems based on trivalent lanthanide ions that exploit the unique photophysical properties of these ions to implement Boolean logic operations. This focus article provides a comprehensive introduction to the principles, methodologies, and recent advancements in luminescence-driven molecular computing. Designed for newcomers, it outlines the fundamental concepts, essential experimental techniques, and standardized protocols for characterizing luminescent molecular logic devices. The advantages of these devices, such as energy efficiency, multiplexing capabilities, and adaptability to complex environments, are also critically examined. Addressing some limitations of traditional electronics, molecular logic paves the way for innovative applications in diagnostics, sensing, and novel computational architectures, offering a transformative and sustainable pathway for next-generation information processing.

The growing plastic pollution crisis demands novel approaches, with innovative materials that mimic robotic behaviors emerging as a promising solution. This approach explores the development and application of smart materials that can autonomously engage in plastic waste removal, functioning like robots under various environmental conditions. We focus on materials activated by light, magnetic fields, chemical fuels, and ion exchange, which are designed to target and remove plastic waste efficiently. The key properties of these materials, such as self-activation, adaptability, and precision that enable them to function autonomously in waste management systems, are examined. The integration of these innovative materials offers significant advantages, including faster waste processing, reduced human exposure to hazardous waste, and enhanced sorting accuracy. Additionally, this review evaluates the environmental impact, scalability, and cost-effectiveness of these materials in comparison to traditional methods. Finally, the potential of these materials to play a central role in sustainable plastic waste management and contribute to a circular economy is discussed.

Supercapacitors, a class of electrochemical energy storage devices, offer a promising solution for powering wearable bioelectronics and implantable biomedical devices. Their high-power density, rapid charge-discharge capabilities, and long cycle life make them ideal for applications requiring quick bursts of energy and extended operation. To address the challenges of energy density, self-discharge, miniaturization, integration, and power consumption, researchers are exploring various strategies, including developing novel electrode materials, optimizing device architectures, and integrating advanced fabrication techniques. Metal oxides, carbon-based materials, MXenes, and their composites have emerged as promising electrode materials due to their high specific surface area, excellent conductivity, and biocompatibility. For wearable bioelectronics, supercapacitors can power a wide range of devices, including wearable sensors, smart textiles, and other devices that require intermittent or pulsed energy. In implantable biomedical devices, supercapacitors offer a reliable and safe power source for applications such as pacemakers, neural implants, and drug delivery systems. By addressing the challenges and capitalizing on emerging technologies, supercapacitors have the potential to revolutionize the field of bioelectronics and biomedical engineering, enabling the development of innovative devices that improve healthcare and quality of life.

In alignment with circular economy principles, we have developed a reprocessable, self-reporting thermoset based on polyethylene. The self-reporting feature is achieved using a mechanophore as the crosslinking agent, which reversibly responds to applied stress while being quenched by thermal stimuli. This same heat trigger also facilitates the material's self-healing capability, ensuring efficient recovery and reusability. The chosen mechanophore is rhodamine, a widely recognized fluorescent dye known for its excellent stability, high absorption coefficient, and long-wavelength absorption and emission. For the covalent reversible bonds, we employ silylether exchange chemistry, as it enables the incorporation of crosslinker units without necessitating modifications to the polymer backbone.

Magnetic hyperthermia using heat locally generated by magnetic nanoparticles (MNPs) under an alternating magnetic field (AMF) to ablate cancer cells has attracted enormous attention. The high accumulation of MNPs and slow heat dissipation generated in tumors are considered the dominant factors involved in magnetic hyperthermia. However, the influence of intracellular microenvironment on magnetic hyperthermia has been ignored. This study unveiled for the first time the critical role of intracellular microenvironment on magnetic hyperthermia. The intracellular microenvironments of cancer cells and normal cells showed different influence on the magnetothermal properties and magnetic hyperthermia effects of MNPs. The MNPs in cancer cells could generate higher temperatures and induce higher rates of apoptosis than those in normal cells. Compared with that of normal cells, the intracellular microenvironment of cancer cells was more conducive to Brownian relaxation and the dynamic magnetic response of internalized MNPs. The cancerous intracellular microenvironment had a discriminative effect on the magnetic hyperthermal effect of MNPs due to the low viscoelasticity of cancer cells, which was verified by the softening or stiffening of cells and simulation models created using viscous liquids or elastic hydrogels. These findings suggest that the intracellular microenvironment should be considered another critical factor of the magnetic hyperthermal effect of MNPs.

Two-dimensional (2D) GaN with a tunable bandgap, high electron mobility, and high chemical and thermal stabilities is an ideal choice for high-performance UV-B photodetectors (PDs). However, the realization of 2D GaN based UV-B PDs faces the challenge of simultaneously achieving large-scale preparation and band engineering. In this work, novel UV-B PDs based on wafer-scale 2D GaN/Si heterojunctions have been proposed. Wafer-scale synthesis and band engineering of 2D GaN are realized via a two-step method consisting of magnetron sputtering and high temperature ammonolysis. With well-controlled thickness, the bandgap of 2D GaN is regulated to 3.6 and 4.1 eV. Impressively, novel UV-B PDs based on 2D GaN/Si heterojunctions exhibit a photoresponsivity of 2.2 A W^-1 at 308 nm at 1 V, and a fast response speed with a rise/decay time of 1.3/1.1 ms, simultaneously. This work provides a resolution for high-performance UV-B PDs through the controllable growth of 2D GaN, and the proposed synthesis strategy significantly broadens the application prospects of 2D GaN in the field of UV optoelectronics.