Materials Horizons最新文献

The need for a sustainable hydrogen supply has sparked significant efforts to develop effective liquid hydrogen carriers with high hydrogen content that can be safely stored and undergo controlled hydrogen release. However, a major challenge lies in the ultralow hydrogen evolution rate caused by the direct dehydrogenation of liquid hydrogen carriers. Conventionally, accelerant additives are employed to improve the dehydrogenation rate, but this strategy inevitably sacrifices the hydrogen storage density. Therefore, achieving high-efficiency hydrogen release and high storage density remains a daunting task. Herein, we develop an innovative photothermally-activated suspended biphasic reaction strategy, which absorbs solar radiation and re-radiates infrared photons to induce photothermal evaporation and in situ dehydrogenation of liquid hydrogen carriers, fundamentally circumventing the employment of additives. Furthermore, by leveraging this phase transition-induced biphasic reaction design, the strategy improves the required reaction temperature and drastically lowers hydrogen transport resistance. Therefore, an impressive hydrogen evolution rate of 386 mmol g^-1 h^-1 is achieved from pure formic acid with an ultrahigh hydrogen storage density of 53 g L^-1, representing a threefold improvement in rate compared to state-of-the-art strategies. Our approach introduces a fresh perspective for the dehydrogenation of liquid hydrogen carriers, encompassing formic acid, hydrazine hydrate, and so on, and concurrently guarantees exceptional hydrogen release capabilities and excellent hydrogen storage density.

Bottom-up nano- to micro-fabrication is crucial in modern electronics and optics. Conventional multi-scale array fabrication techniques, however, are facing challenges in reconciling the contradiction between the pursuit of better device performance and lowering the fabrication cost and/or energy consumption. Here, we introduce a facile mixed-metal array fabrication method based on guided self-assembly of polymerizing organometallic adducts derived from the passivating oxides of a ternary liquid metal to create mixed metal wires. Driven by capillary action and evaporation-driven Marangoni convection, large-area, high-quality organometallic nano- to micro-wire arrays were fabricated. Calcination converts the organometallics into oxides (semiconductors) without compromising wire continuity or array periodicity. Exploiting capillary bridges on a preceding layer, hierarchical arrays were made. Similarly, exploiting the conformity of the liquid to the mold, arrays with complex geometries were made. Given the periodicity and high refractive index of these arrays, we observe guided mode resonance while their complex band structures enable fabrication of diodes or gates. This work demonstrates a simple, affordable approach to opto-electronics based on self-assembling arrays.

The 'pyro-phototronic effect' plays a nontrivial role in advancing ferroelectric (FE) devices of light detectors, light-emitting diodes, and other smart technologies. In this work, a premier FE copolymer, poly(vinylidene fluoride-co-trifluoro ethylene) (P(VDF-TrFE)), is reinforced with a lead-free double perovskite, Cs₂SnI₆, to render profound properties in a hybrid nanostructure. It presents a unique example of the coupling of ferro-, pyro- and piezo-electrics to the 'photoexcitation' of exotic charges that actively empower the synergetic features. Cs₂SnI₆ embodied in small crystallites therein is distorted in a non-centrosymmetric class of a rhomboid crystal structure (a new phase) rather than a well-known centrosymmetric face-centred cubic (fcc) phase. It boosts the emerging phototronic properties. A systematic study of the bulk heterojunction reveals the four-stage pyro-phototronic response of transient photocurrent under visible light illumination of a solar simulator (intensity ∼100 mW cm^-2). Illumination at a frequency of 0.025 Hz induces a temporal temperature change, ΔT → 3.1 K, in the system, leading to induced pyroelectricity in an integrated circuit. The rise time and response time for the heterojunction are observed as ∼326 ms and ∼225 ms, respectively. The output pyro-phototronic current increases as ΔT increases in an on-off cycle. As a result, the integrated pyro-phototronic effect can be utilized to empower optoelectronic devices and harvest stray 'thermal energy' for running small energy devices.

Owing to their unique and tunable optoelectronic and magnetic properties, organic conjugated radicals have great potential in information storage and communication through modulating the molecular spin states. However, few electronic/spintronic devices based on these materials have been reported to date due to various intrinsic constraints such as poor material stability and processability. In this work, we have synthesized a stable singlet ground state organic conjugated diradical 5,7-dimesityl-s-indaceno[1,2-b:7,6-b']dipyridine (mNIF) with narrow band gap (1.16 eV) and small singlet-triplet energy gap (ΔE_S-T = -1.05 kcal mol^-1). mNIF showed good ambient stability and processability, and we have successfully fabricated a single ferromagnetic electrode device based on it with the structure of Ti/Au/mNIF/Co/Au. Distinct interface magnetoresistance effects were observed when the device was tested at different temperatures, which were attributed to the temperature anisotropy of the interface magnetic layer due to the small ΔE_S-T. Nevertheless, no interface magnetoresistance effect was observed in the device based on its syn analogous closed-shell molecule. Our work demonstrates the potential application of organic conjugated radicals in quantum memory.

Homojunction engineering holds promise for creating high-performance photocatalysts, yet significant challenges persist in establishing and modulating an effective junction interface. To tackle this, we designed and constructed a novel Janus homojunction photocatalyst by integrating two different forms of triazole-based carbon nitride (C₃N₅). In this design, super-sized, ultrathin nanosheets of carbon-rich C₃N₅ grow epitaxially on a nitrogen-rich honeycomb network of C₃N₅, creating a tightly bound and extensive interfacial contact area. This arrangement enhances the built-in internal electric field (IEF) between the two forms of C₃N₅, facilitating faster directional transfer of photogenerated electrons and improved visible-light harvesting. Consequently, Janus-C₃N₅ achieves a remarkable H₂ evolution rate of 1712.4 μmol h^-1 g^-1 under simulated sunlight, which is approximately 5.58 times higher than that of bulk C₃N₅ (306.8 μmol h^-1 g^-1) and 14.1 times higher than another form of bulk C₃N₅ (121.2 μmol h^-1 g^-1). This work offers a new approach to design efficient homojunction-based photocatalysts.

The development of multi-cation perovskite quantum dots (PQDs) is limited by the low availability of fitting A-site cations due to the unsuitable radii of a large gamut of amine cations. The impact of oversized or undersized cations on the perovskite structure is detrimental to the structural stabilization and electroluminescence efficiency of the PQDs. Researchers are actively seeking suitable-sized cations to mitigate perovskite defect formation and optimize charge carrier confinement within the PQDs. In contrast to cesium (Cs) or formamidine (FA), which are exposed to degradation pathways, guanidinium (GA)-doping has been to provide a suitable radius and the lack a dipole moment. The triple nitrogen functionality of GA enables it to passivate both the PbBr₆ octahedra and surface defects through vacant A-sites and entropically stabilize the perovskite. Furthermore, the insertion of GA into the PQD lattice is enthalpically facilitated by the presence and arrangement of smaller Cs and Br atoms. Herein, we have synthesized a Cs-FA PQD reference into which GA is doped via two chemical routes. Our triple-cation system exhibits substantially improved optical properties and was applied for the fabrication of a PeLED device. The optimized triple-cation PQDs-based PeLED device exhibited an external quantum efficiency of 5.87% and a luminescence of 13726 cd m^-2.

Widespread electromagnetic (EM) interference and pollution have become major issues due to the rapid advancement of fifth-generation (5G) wireless communication technology and devices. Recent advances in high-entropy (HE) materials have opened new opportunities for exploring EM wave absorption abilities to address the issues. The lattice distortion effect of structures, the synergistic effect of multi-element components, and multiple dielectric/magnetic loss mechanisms can offer extensive possibilities for optimizing the balance between impedance matching and attenuation ability, resulting in superior EM wave absorption performance. This review gives a comprehensive review on the recent progress of HE materials for EM wave absorption. We begin with the fundamentals of EM wave absorption materials and the superiority of HE absorbers. Discussions of advanced synthetic methods, in-depth characterization techniques, and electronic properties, especially with regard to regulatable electronic structures through band engineering of HE materials are highlighted. This review also covers current research advancements in a wide variety of HE materials for EM wave absorption, including HE alloys, HE ceramics (mainly HE oxides, carbides, and borides), and other novel HE systems. Finally, insights into future directions for the further development of high-performance HE EM wave absorbers are provided.

Liquid metal (LM) technologies are rapidly advancing in modern materials science, with low melting point metals playing a pivotal role in emerging applications. Recent studies reveal that doped liquid gallium systems form spectacular and diverse surface structures during cooling, [Tang et al., Nat. Nanotechnol., 2021, 16, 431-439] sparking renewed interest in the possible geometric structuring at the surface of pure liquid gallium. Distinct from the known increase in surface density, this lateral surface order has long been hinted at experimentally and theoretically but has remained enigmatic. Here, we quantitatively characterise the depth and nature of this surface ordering for the first time, using highly accurate and large scale molecular dynamics simulations coupled with machine learning analysis techniques. We also quantify the enhanced structural order introduced by the addition of a gallium oxide film as well as the disruption due to a dopant (bismuth).

Close integration of metal nanoparticles (NPs) into a metal-organic framework (MOF) can be leveraged to achieve tailored functionality of the resulting composite structure. Here, we demonstrate a "ship-in-a-bottle" approach to produce ≈4.0 nm bismuth (Bi) NPs within a thiol-rich zirconium-based MOF of Zr-DMBD (DMBD = 2,5-dimercapto-1,4-benzenedicarboxylate). We found that the incorporation of Bi NPs into the Zr-DMBD framework relies on the free-standing thiol groups. These thiols have two roles - (i) aid in binding precursor Bi³⁺ preventing to form the insoluble bismuthyl unit (BiO⁺) and (ii) controlling the growth of Bi NPs. The resulting composite, denoted as BiNP@Zr-DMBD-1, displayed enhanced catalytic activity due to strong interactions between Bi NPs and organic linkers mediated by sulfur, promoting charge transfer from the Bi NP to the MOF matrix. BiNP@Zr-DMBD-1 remained stable after CO₂ electroreduction to formate in a flow setting, with >88% faradaic efficiency at 25 mA cm^-2 current density. Additionally, BiNP@Zr-DMBD-1 composite was shown to exhibit photoactivity beyond the typical near-UV absorption range of Bi NPs, where it completely degraded methylene blue dye within 1 h of blue LED irradiation. This work therefore underlines the potential of thiol-rich MOFs in developing new nanomaterials for diverse catalytic applications.

The growing risk of bacterial food poisoning due to global warming has necessitated the development of methods for accurate detection of food-poisoning bacteria. Despite extensive efforts to develop enhanced bacterial-capture methods, challenges associated with the release of the captured bacteria have limited the sensitivity of bacterial detection. In this study, thermo-responsive intelligent 3D nanostructures to improve food-poisoning bacterial analysis performance were fabricated by introducing a thermo-responsive polymer onto an urchin-like 3D nanopillar substrate (URCHANO). A co-polymer of methacryloyl glycinamide and benzyl acrylate (MNAGA-Bn 5%) was introduced as a thermo-responsive co-polymer onto URCHANO using an electron-transfer atom-transfer radical-polymerization method to fabricate Thermo-URCHANO. A temperature-related analysis of the surface properties of Thermo-URCHANO revealed a hydrophobic-to-hydrophilic transition at 37 °C, which facilitated the release of bacteria captured within the nanostructure. In a one-pot analysis to capture and analyze various food-poisoning bacteria in kitchenware (gloves and aprons) and food items (eggs and sausages), mimicking real-life environments, specimens collected using Thermo-URCHANO showed lower C_t values than those collected with uncoated URCHANO, indicating greater bacterial detection. This method could effectively release captured bacteria through temperature changes, improving extraction efficiency during swab collection. While Thermo-URCHANO needs further optimization, it is expected to enhance bacterial analysis performance and sensitivity.