Materials Horizons最新文献

Polymer-based thermally conductive composites with ultrahigh in-plane thermal conductivity are ideal candidates for heat dissipation applications in electronics. However, the complex interfaces between the functional filler and polymer matrix limit the significant increase in thermal conductivity of the polymer composites. In this study, we developed a one-pot strategy to prepare highly thermally conductive composite films of freeze-expansion large-size graphite microplatelets (F-GMPs) and aramid nanofibers (ANFs) with π-π interactions. The obtained F-GMP/ANF nanocomposite films present salient in-plane thermal conductivity, considerable flexibility, and outstanding long-term stability. The π-π interactions between the F-GMPs and ANFs promote the freeze-expansion exfoliation of graphite, yielding stable F-GMP/ANF precursor pastes with high-quality graphite platelets. Moreover, the π-π interactions improve the filler-matrix interfacial compatibility and reduce the interfacial thermal resistance, while the large-size F-GMP particles are directly lapped to construct a thermal transfer pathway with a reduction in the filler-filler interfacial thermal resistance. Consequently, the F-GMP/ANF composite films with 30 wt% F-GMPs exhibit unprecedentedly high in-plane thermal conductivity (56.89 W m^-1 K^-1) and corresponding thermal conductivity enhancement efficiency, presenting great application potential for the effective thermal management of highly integrated electronics.

The development and utilization of airspace, especially near-space particularly rely on power units with superior tolerance in low-temperature and low-pressure environments to output a stable energy supply. Here we propose a strategy towards low-temperature, low-pressure Zn-ion hybrid supercapacitor based on a weakly hydrogen-bonded electrolyte and a hyacinth-shaped Ti₂CT_x MXene@CC cathode with hierarchical bridge-linked structure, which synergistically reduces the internal resistance of the device and enables the assembled supercapacitor showing a good low-temperature resistance while combining low-gas-voltage safety. The ACN additive weakens the hydrogen bond between water molecules and reshapes the solvation structure of Zn²⁺, thus reducing the ion transfer resistance and achieving a reversible Zn/Zn²⁺ chemical reaction. The bridge-linked hierarchical structure of the hyacinth-shaped Ti₂CT_x MXene@CC cathode provides a rich conductive network and optimizes the ion diffusion path, which reduces the ion diffusion resistance. At -40 °C, the assembled device can still achieve an area specific capacitance of 64.0 mF cm^-2 at a scan rate of 500 mV s^-1, and long-term stability after 20 000 cycles at a current density of 20 mA cm^-2. An integrated temperature and pressure sensing system driven by the supercapacitor successfully realizes the monitoring of atmospheric indicators in extreme environments, providing new ideas for auxiliary power units in airspace and near-space.

In the pursuit of efficient fuel production, the challenges posed by the requirement of an external power source have prompted the need for self-powered energy systems by obtaining energy from the environment. Until now, significant progress on developing self-powered energy systems has been made. However, a more basic and in-depth study on their configuration is required for industrial applications. In this review, we outline the latest advancements of self-powered electrochemical energy systems constructed with solar energy, rechargeable batteries/fuel cells and triboelectric nanogenerators. Critical evaluations of the electrochemistry are highlighted to address the issues in elevating the efficiency of fuel production. In addition, the existing challenges and future prospects are also discussed, aiming to develop highly-efficient self-powered energy systems for green fuel production in the future.

Polycarbonate is an advanced engineering plastic widely used in aerospace, high-speed rail and 5G communications. However, it remains a huge challenge to synthesize polycarbonate materials using a strategy that simultaneously integrates green-preparation, service-stage advanced-performance and end-of-life easy-recyclability. Herein, we propose an ultrahigh-efficiency and green halogen/phosphorus-free strategy to prepare a mechanically robust, highly transparent, super-fire-resistant and chemically easily recyclable polycarbonate plastic. By chemical copolymerization of only catalytic amounts of sodium sulfonate-naphthol (0.3-0.5 mol%, namely 3400-5600 ppm), the corresponding polycarbonates exhibit >85 MPa tensile strength, >67 kJ m^-2 notched impact strength, >90% transparency, >36% ultra-high limiting oxygen index and 1.6 mm thin-wall UL-94 V-0 rating during the service-stage. Especially, at the end-of-life, these polycarbonates can be easily depolymerized back to the raw monomer bisphenol A and high-value 2-oxazolidinone under mild conditions (50 °C for 4 h), achieving ultra-high atom-economic chemical recycling. Starting from the source of a chemical structure, this work opens up a new perspective for constructing life cycle-managed plastic materials with advanced high-performance and full-recyclability, contributing to the global circular economy through sustainable material design.

Optoelectronic synapses (OES) inspired by the human brain have gained attention in addressing the von Neumann bottleneck facing traditional computing. Numerous candidates, including topological insulators and other 2D materials, have been used to fabricate OES devices with different degrees of success. Se vacancies commonly appearing in epitaxially grown Bi₂Se₃ and importantly the ability to modulate the vacancies by changing the growth temperature make it a worthy candidate to construct an OES system. The vacancies effectively trap and release charges, leading to persistent photoconductivity, which is the mechanism behind OES operation. A defect-induced Bi₂Se₃-based synapse using an ultrathin layer grown by chemical vapor deposition is shown herein to successfully demonstrate basic synapse characteristics such as paired-pulse facilitation (PPF), short-term and long-term memory, and learning-relearning behavior. This OES device shows a very high PPF index of 201.7%, a long memory retention time of 523.1 s, and an ultralow energy consumption of 9.2 fJ per spike, which is at the low end of the 1-100 fJ range for biological systems. Density functional theory simulations reinforce the definite role of trap centers induced by the Se vacancies in the device operation. Our device realizes a high recognition accuracy of 90.12% for MNIST handwritten digital images in simulations based on an artificial neural network algorithm. The exceptional results achieved here show the potential of Bi₂Se₃ for synaptic applications and pave the way for exploiting its potential in future high-performance neuromorphic computing and other artificial visual perception systems.

Synergistic enhancement of luminescence and ferroelectricity (SELF) was explored in a (Z)-isomer of tetraphenylethene derivatives containing two clipping units in (Z)-configuration (TPC2-(Z)). TPC2-(Z) was synthesized utilizing a 'body core' precursor, which exclusively afforded (Z)-configuration. High-resolution transmission electron microscopy measurements indicated that TPC2-(Z) formed a layered morphology in film, with well-ordered crystalline structures, which was ascribed to the (Z)-clipped self-assembled structures. The film exhibited good photoluminescence performances with 45.6% quantum yield. Simultaneously, the film exhibited high ferroelectricity as inferred from high remnant polarization (P_r = 2.54 μC cm^-2) and saturated polarization (3.56 μC cm^-2) along with a longitudinal piezoelectric coefficient (d₃₃ = -23.8 pm V^-1), indicating that TPC2-(Z) exhibits excellent SELF. Owing to its fluorescence and thermal stability, we fabricated light-emitting electrochemical cells (LEC) that exhibited maximum 890 cd m^-2 at V_on of 3.9 V. This was more than 40% enhanced performance compared to that of the (E)/(Z) mixture. A new self-powered, stimuli-sensitive electroluminescent device was demonstrated with TPC2-(Z), where the piezoelectrically tunable LECs effectively 'switched on' luminescence, showing 120-fold increased brightness after 254 bending at 1 Hz, compared to the 'off' state without bending. These results underscore that Z-clipping is an effective method for enhancing SELF and could create new self-powered, stimuli-sensitive electroluminescent devices.

Structural color-based impact sensors output light or electrical signals through entropic elasticity storing and releasing of the polymer network, inspiring the design of armors for underwater equipment. Designing self-damping units at the molecular and nanostructural levels will contribute to capturing and analyzing relevant impact and mechanical signals by the naked eye. Herein, inspired by the octopus' sucker, we proposed self-damping photonic crystals (SDPCs) with differentiated reversible crosslinking domains, which can delayed-release entropic elasticity in water and visually perceive stress field evolution via structural color. These domains are generated by weak and strong hydrogen bonds (H-bonds) assigned by differentiated copolymerization, corresponding to weak and strong crosslinking domains, respectively. The compressed network stores entropic elasticity, showing size-effect-induced blueshift structural colors. During entropic elasticity release, the weak/strong crosslinking domains are disrupted successively, resulting in temporary macropore asymmetry and forming transient Laplacian pressure difference (ΔP). The self-damping effect based on the continuous recombination of domains and the equilibrium iteration of ΔP achieves a delayed visual perception of entropy elasticity release. Given this, impact stress sensing and structural color self-erasing techniques have been developed.

Traditional flexible electronic sensing materials have fallen short in meeting the diverse application needs and environments of modern times. Hence, we require a multi-functional elastomer material to improve the overall performance and expand the functionality of flexible electronic sensors. In this study, we fabricated a multi-block polyurethane (PU) elastomer based on semi-crystalline polycaprolactone (PCL) chain segments and highly flexible polydimethylsiloxane (PDMS) chain segments, which showcases outstanding mechanical properties, self-healing capabilities, and recyclability. By adjusting the ratio parameters of the chain segments, we were able to modulate the thermodynamic behavior, hydrophobicity, mechanical behavior, and self-healing properties of the designed PU elastomers. The optimized ratios exhibited good tensile strength (16.26 MPa), high elongation at break (3300.84%), good toughness (278.82 MJ m^-3, fracture energy ≈ 234.96 KJ m^-2), high self-repairing (≈100%, at room temperature for 12 h), efficient recyclability, and puncture resistance. Self-healing is accomplished through the interactions between dynamic disulfide bonds, dynamic boron-oxygen bonds, and hydrogen bonds. The conductive ink (PEDOT:PSS) was encapsulated within this elastomer to construct a flexible electronic sensor, attaining excellent sensing performance (stable output for 1000 cycles). This multi-functional polyurethane elastomer acts as an ideal matrix material for flexible electronic sensors, offering novel concepts and perspectives for the next generation of green electronic flexible materials, electronic flexible robots, and other stimulus-responsive materials.

The development of advanced environmentally friendly energy storage capacitors is critical to meet escalating demands of pulsed power systems. However, challenges persist in enhancing both the recoverable energy density (W_rec) and efficiency (η) simultaneously. In the present study, a strategy involving domain configuration modulation, achieved by simple single rare earth ion doping, was proposed to enhance the energy-storage performance of BaTiO₃. The designed Ba_1-1.5xLa_xTiO₃ (BLT-x) ceramics exhibited an ultrahigh W_rec of 9.2 J cm^-3 and η of 85.0% when x = 0.10. Furthermore, the origin of the superior performance was revealed through first-principles calculations and atomic-scale displacement analysis. The introduction of La generated intense structural fluctuations in the ordered ferroelectric domains, leading to relaxors with weakly coupled polar nanoregions and delayed saturation polarization. Such factors, combined with enhanced E_b, contributed to elongated P-E loops and ultimately ultrahigh W_rec and η. Meanwhile, the BLT-0.10 ceramic demonstrated exceptional temperature stability (-40-120 °C), frequency stability (10-250 Hz) and fatigue stability (10⁶ cycles), along with notable charging-discharging capabilities. The present research not only provides a potential candidate for advanced pulsed power systems, but also offers a novel strategy for achieving superior energy-storage performance in perovskite ferroelectrics through single rare earth ion-doping.

The rapid advancement of indoor perovskite solar cells (IPSCs) stems from the growing demand for sustainable energy solutions and the proliferation of internet of things (IoT) devices. With tunable bandgaps and superior light absorption properties, perovskites efficiently harvest energy from artificial light sources like LEDs and fluorescent lamps, positioning IPSCs as a promising solution for powering smart homes, sensor networks, and portable electronics. In this review, we introduce recent research that highlights advancements in material optimization under low-light conditions, such as tailoring wide-bandgap perovskites to match indoor light spectra and minimizing defects to enhance stability. Notably, our review explores the integration of artificial intelligence (AI) and machine learning (ML), which are transforming IPSC development by facilitating efficient material discovery, optimizing device architectures, and uncovering degradation mechanisms. These advancements are driving the realization of sustainable indoor energy solutions for interconnected smart technologies.