Small Methods最新文献

The low-temperature synthesis of transition metal dichalcogenides (TMDCs) is essential for next-generation electronics, but this process remains a challenge. Generally, conventional methods require high temperatures, whereas existing low-temperature approaches depend on extrinsic modifications, such as plasma enhancement or specialized precursors, to enhance reactivity. In this study, a novel fundamental strategy was introduced on the basis of the intrinsic electronic engineering of transition metals (TMs). A bilayered junction protocol was proposed, where a buffer TM (b-TM) is placed beneath the target TM (t-TM) to facilitate TMDC synthesis. This junction precisely controls interfacial charge transfer, directly modulating the density of states (DOS) at the Fermi level of t-TM. The choice of b-TM enables the bidirectional tuning of DOS at the Fermi level of t-TM, thereby influencing chalcogen precursor adsorption and systematically reducing the required synthesis temperature. Using this approach, uniform, large-area TMDC nanosheets (exceeding 5.5 inches) were synthesized at remarkably low temperatures even on glass substrates, demonstrating the method's broad applicability. We have also demonstrated this capability with various TMDCs, including MoS₂, WS₂, MoSe₂, and WSe₂. Notably, all 25 fabricated memristor arrays on these films demonstrated exceptional performance, achieving remarkably uniform and ultra-low Set/Reset voltage profiles (±0.15 V). This work establishes a new paradigm for low-temperature synthesis of TMDCs, potentially applicable to the entire class of TMDCs, paving the way for advanced electronic applications on flexible and transparent substrates.

Flexible sensors demonstrate exceptional adaptability across human-computer interaction, health monitoring, and robotic systems. However, sensing materials suffer from inadequate conformation capability and microstructural inaccuracies, resulting in function deficiencies. This review examines composite hydrogel formulations that incorporate conductive nanofillers, with particular emphasis on 2D nanomaterials, whose functional tunability enables precise regulation of electrical and interfacial properties. The strategic integration of microstructures further improves sensor sensitivity, durability, and environmental adaptability. We also examine implementation of flexible sensors based on 3D-printed hydrogel in emerging applications including pH monitoring, glucose detection, and food safety assessment. We suggest that future development prioritize elucidating sensing mechanisms, achieving multifunctional integration, advancing material engineering, and refining precision manufacturing. Particularly promising research directions include developing intelligent tactile feedback systems for humanoid robots and creating capsule robot-integrated platforms for gastrointestinal disease monitoring.

Solar-driven interfacial evaporation holds promise for addressing freshwater scarcity, yet its long-term performance is compromised by salt fouling. Herein, we present a 3D dispersed interfacial evaporator that synergistically integrates the "skin effect" and "ion-pumping effect" to enhance vapor generation and salt resistance. The evaporator was prepared by deposition of a chemically crosslinked polyvinyl alcohol/clay composite hydrogel onto polyester aroma sticks to improve hydrophilicity and stabilize capillary channels, and then deposition of Cu-MOF nanocrystals to provide broad-spectrum light absorption (>90%). Under 1 kW m^-2 illumination, the evaporator achieved average evaporation rates of 4.68 and 4.36 kg m^-2 h^-1 during 10 h of continuous operation in 3.5 wt.% and 20 wt.% NaCl solutions, respectively. Further structural optimization using ambient wind flow boosts the evaporation rate to 15.82 kg m^-2 h^-1 at a wind speed of 1 m s^-1. Mechanistic investigations reveal the skin effect mitigates structural degradation by restricting salt crystallization to surface layers, while the ion-pumping effect promotes ion diffusion to prevent salt accumulation. Outdoor tests verify that ion concentrations in the harvested freshwater comply with the WHO drinking water standards. This study demonstrates a viable strategy for robust, high-efficiency, salt-tolerant solar desalination under diverse environmental conditions.

Inverted inorganic CsPbIBr₂ perovskite solar cells (PSCs) employing NiO_x as the hole-transport layer are promising long-term stable and semi-transparent photovoltaic devices. Nevertheless, their performance is often constrained by unfavorable interfacial phenomena, including detrimental redox reactions between Ni³⁺ in NiO_x and I^- in perovskite, as well as band energy misalignment at the NiO_x/CsPbIBr₂ interface. In this work, we introduce an N-dodecylphosphonic acid (NDPA) interfacial modification strategy, where the phosphonic groups of NDPA anchor onto the NiO_x surface. This tailored interface not only suppresses interfacial redox reactions but also alleviates energy level mismatch and releases the residual tensile stress, thereby facilitating charge transport and reducing non-radiative recombination losses. As a result, the optimized PSCs deliver a champion power conversion efficiency of 9.28% with a high open-circuit voltage (V_oc) of 1.12 V, positioning it among the best-performing inverted CsPbIBr₂ PSCs reported to date. The modified devices retain 79% of their initial efficiency after 1300 h of storage in a nitrogen-filled glovebox, underscoring their potential for practical photovoltaic applications.

Polymer-based fluorescent nanoparticles (NPs) are the brightest tool in developing the fields of bioimaging, diagnostics, and sensing. By translating existing fluorophores to a nanoparticle platform, photostability and the fluorescent signal can be drastically increased, while enabling the use of lipophilic dyes in aqueous media. This expands the fluorescent probe toolbox and dramatically increases signal fidelity. Here, we use perylene diimide (PDI) loaded polystyrene nanoparticles as a platform to investigate the effects of surfactant capping and dye loading, and we demonstrate nanoparticle stability, pH invariability, and increased emission intensity. The target is PDI loaded NPs that provide properties identical to a perfectly water soluble PDI dye, that is, a component with a nanosecond lifetime and bright emission in the orange. This was achieved by increasing the PDI loading of the NPs beyond where quenching was expected, which resulted in a new class of nanoparticles that are 100 times brighter than PDI and stable for months. These findings indicate that the usual design paradigm: "Less is more" for fluorescent dye loading is not always the optimal solution to achieve the maximal signal.

Carbon dioxide (CO₂) separation and capture technologie have been considered as a viable strategy for mitigating CO₂ emissions to reduce the greenhouse effect. Metal organic frameworks (MOFs)-based membrane separation technology has demonstrated to be an efficient and sustainable approach for CO₂ separation and capture compared to the conventional methods. The development of high-performance materials and fabrication techniques, assisted with modern computational methods, has become an active research area. In this review, the state of the art and applications of MOFs-based membrane for CO₂ separation technology were summarized, and the materials synthesis and modification methods reported in the last five years were comprehensively compared to evaluate the advantages and limitations in improving the permeability and selectivity of the membranes. The most recent progress of computational methods involving molecular simulations and machine learning was outlined to understand the underlying molecular mechanisms of the separation performance and high-throughput screening of materials. Finally, the challenges and prospects of the current development status of MOFs-based membranes in both experiments and data-driven methods for CO₂ separation were addressed.

Iron pyrite (FeS₂) is a promising material for next-generation photovoltaic and optoelectronic applications. However, the origin of p-type conductivity in thin films, unlike the n-type behavior of bulk FeS₂, remains unknown and is often attributed to unintentional impurity incorporation, particularly oxygen. This study explores the role of oxygen in tuning the electrical and optical properties of FeS₂ thin films. Phase-pure FeS₂ thin film is deposited on glass substrates via single-step co-sputtering using FeS₂ and S₈ targets at 430°C substrate temperature. The resulting films exhibit p-type conductivity with a carrier concentration and mobility of 4.18 × 10¹⁹ cm^-3 and 5.06 cm² V^-1 s^-1 respectively. Controlled oxygen incorporation is achieved through negative ion implantation at fluences ranging from 9 × 10¹⁴ to 1 × 10¹⁶ ions cm^-2. X-ray photoelectron spectroscopy and time of flight secondary ion mass spectrometry confirm successful oxygen doping, with oxygen atoms preferentially occupying sulfur vacancies for higher doses. This incorporation enhances p-type conductivity and induces direct bandgap widening up to 1.48 eV. The results demonstrate a pathway to fabricate FeS₂ thin films with high hole concentration and offer a strategy for optimizing the optoelectronic properties for advanced semiconductor applications.

The blood-brain barrier (BBB), formed by brain microvascular endothelial cells (BMECs), restricts vascular permeability through tight junctions, selective transporters, and low transcytosis. BBB dysfunction contributes to cerebrovascular and neurodegenerative disease, yet current human in vitro models recapitulate only a subset of BMEC features. Here, we describe a strategy generate BMECs (hiBMECs) from human induced pluripotent stem cell-derived endothelial cells by co-culture with isogenic brain pericytes and activation of Wnt/β-catenin signaling. The resulting hiBMECs display barrier properties, active efflux transporters, and appropriate inflammatory responses. Transcriptomic profiling revealed convergence of pericyte-derived cues and Wnt/β-catenin activation on ETS1, SMAD3/4, and PPARγ transcriptional networks, establishing a gene signature closely matching the adult human BBB. Downstream analysis revealed that hiBPC cues engaged sphingosine-1-phosphate, TGF-β, and angiopoietin/Tie2 pathways, which were further regulated by canonical Wnt activation. These findings uncover a synergistic mechanism by which brain pericytes and Wnt/β-catenin signaling orchestrate BMEC differentiation and function, providing mechanistic insight into human BBB development and an improved hiPSC-derived BBB model for future drug screening and disease modeling.

While state-of-the-art alloy catalysts for the oxygen reduction reaction (ORR), a key process for future sustainable energy provision, rely on platinum-rich materials, alloys containing less noble metals may play an increasingly important role. In particular, Cu-Pt systems are among state-of-the-art electrocatalysts for O₂ electro-reduction, demonstrating high activity and selectivity for the four-electron pathway. This study explores the behavior of Cu-Pt model thin film alloy catalysts using electrochemical scanning tunneling microscopy (EC-STM), a technique capable of detecting active sites and areas for surface catalytic processes under reaction conditions. Our findings indicate that the nature of active centers changes depending on whether the final product is H₂O or H₂O_2, which can also be generated in parallel. Active centers are located on the (111) terraces for the four-electron ORR and shift to step defects if the hydrogen peroxide generation starts. On the other hand, the grain boundaries do not seem to contribute to the sample activity. These findings can be used in designing the shape of nanoparticles for improved nanostructured materials for energy applications.

Inspired by human skin, electronic skin (e-skin) integrates multidisciplinary technologies from materials engineering to microelectronics. It aims to replicate the skin's ability to perceive pressure, temperature, and humidity while also exhibiting excellent biocompatibility. As an emerging technology, e-skin holds significant promise across diverse fields, including industry, medicine, the military, and robotics. This review summarizes recent progress in the structural design of e-skin, which is a pivotal factor enabling breakthroughs in its functionality and performance. The e-skin structural design strategies are classified into three categories: skin-like perception regulation and performance enhancement, conformal interface stabilization design, and beyond-skin functionality design. These strategies facilitate skin-like multimodal sensing, stable human-machine interfaces, and capabilities exceeding those of biological skin, respectively. Current challenges and future prospects for e-skin development are also discussed.