Nano Research最新文献

The solid-electrolyte-based memristors have attracted tremendous attention for the next-generation nonvolatile memory for both logic and neuromorphic applications. However, they encounter variability performance challenges which originated from the random ionic transport and conductive filaments formation. Evidently, the electrochemical metallized mechanism associated with ion transport has been elucidated. Nonetheless, the failure mechanism caused by ion transport during cycles is rarely reported. Hereafter, the five stages of failure in the Ag/Ag₁₀Ge₁₅Te₇₅/W memristor are elucidated through ex-situ current-voltage measurements combined with in-situ transmission electron microscopy characteristics. Our investigation reveals that the migration and enrichment of Ag ions result in the precipitation of Ag₂Te. The formation of Ag₂Te hinders the device’s ability to maintain its bipolar characteristics and also decreases the resistance value of the high resistance state, thereby reducing the device’s switching ratio. The promising results provide important guidance for the future design of structures and the manipulation of ion transport for high-performance memristors.

Hot spot engineering in plasmonic nanostructures plays a significant role in surface-enhanced Raman scattering (SERS) for bioanalysis and cell imaging. However, creating stable, reproducible, and strong SERS signals remains challenging due to the potential interference from surrounding chemicals and locating SERS-active analytes into hot-spot regions. Herein, we developed a straightforward approach to synthesize intra-gap nanoparticles encapsulating 4-nitrobenzenethiol (4-NBT) as a reporter molecule within these gaps to avoid outside interference. We made three kinds of intra-gap nanoparticles using nanorods, bipyramids, and nanospheres as cores, in which the nanorods based intra-gap nanoparticles exhibit the highest SERS activity. The advantage of our method is the ease of preparation of high-yield and stable intra-gap nanoparticles characterized by a short incubation time (10 min) with 4-NBT and quick synthesis without requiring an additional step to centrifuge for the purification of core nanoparticles. The intense localized field in the synthesized hot spots of these plasmonic gap nanostructures holds great promise as a SERS substrate for a broad range of quantitative optical applications.

As an energy-free cooling technique, radiative cooling has garnered significant attention in the field of energy conservation. However, traditional radiative cooling films often possess static optical properties and their inherent opacity limits their applications in building such as windows. Therefore, there exists a requirement for passive radiative cooling films endowed with adjustable transmittance. Here we report the porous block copolymer films with self-adjustable optical transmittance and passive radiative cooling. In a result, the film exhibited a high solar reflectance (0.3–2.5 µm) of 96.9% and a high infrared emittance (8–13 µm) of 97.9%. Outdoor experiments demonstrated that the film surface temperature was 6.6 °C lower than ambient temperature, with a cooling power of 104.8 W·m⁻². In addition, the film’s transmittance can be regulated by altering the polarity of the postprocessing solvent, providing an effective approach for regulating indoor light intensity and thermal balance, thereby enhancing the applicability of radiative cooling.

Optimization of Pt atom utilization efficiency is critical for the development of proton-exchange-membrane fuel cells. Here we aim to develop an efficient oxygen reduction reaction (ORR) catalyst with a low Pt content through the concurrent modification of Pt-Co alloy catalysts and carbon substrate. In the present study, ultrafine Pt-Co alloy nanoparticles are successfully synthesized and stabilized by topological carbon defects via adopting the ammonia thermal treatment. Despite the low Pt loading, the obtained catalyst exhibits an impressive half-wave potential of 0.926 V versus the reversible hydrogen electrode in 0.1 M HClO₄ electrolyte. Furthermore, the durability testing using the timed-current method demonstrates a tiny loss of only 3.6% after 12 h. Both experimental results and theoretical calculations demonstrate that topological carbon defects significantly enhance the charge transfer processes at the alloy/carbon interface, contributing to the strong electronic metal-support interactions between the Pt-Co alloy nanoparticles and topological carbon defects. These interactions, along with the alloy effect, play a crucial role in promoting the ORR performance in acidic media.

The fabrication of light-weight, highly impact-resistant, and energy-absorbent materials is urgently demanded in many facets of the society from body armor to aerospace engineering, especially under an extreme environment. Carbon nanotubes (CNTs), one of the strongest and toughest materials ever found, also have good conductivity, chemical stability, and thermal stability, etc, making them a competitive candidate as building blocks to help achieve the above goal. In this work, a kind of CNT network was prepared by using chlorosulfonic acid (CSA) to release the internal stress of super-aligned carbon nanotube films (SA-CNTF) and dendritic polyamide amine (PAMAM) to further introduce multiple hydrogen bonds and interlocking structures. The fabricated bioinspired carbon nanotube network films (PAMAM@C-CNTF) have a high toughness of 45.97 MJ/m³, showing an increase of 420% compared to neat SA-CNTF. More importantly, the anti-impact performance of the films (e.g., with a maximum specific energy absorption of 1.40 MJ/kg under 80–100 m/s projectile impact) is superior to that of conventional protective materials from steel and Kevlar fiber, and also exceeds that of any other reported carbon-based materials. The hierarchical energy dissipation mechanism was further revealed through experiment and simulation. Additional functions including intelligent heating/anti-icing, ultraviolet protection, as well as electromagnetic interference shielding properties make these network films have great potential in practical multi-protection applications, especially under an extreme environment.

Multi-phase vertically aligned nanocomposite (MP-VAN) thin films represent a promising avenue for achieving complex multifunctionality, exploring novel interfacial phenomena, and enabling complex metamaterial designs and exploration. In this study, a novel self-assembled all-oxides three-phase VAN system was conceptualized and fabricated utilizing pulsed laser deposition (PLD) with a single composite target. Detailed microstructural analysis reveals the presence of three distinct phases: LiNbO₃, CeO_2−x, and LiNbCe_1−xO_y within the MP-VAN films. Subsequently, ferroelectric, dielectric, optical anisotropy, and magnetic properties were systematically investigated to showcase the multifunctionality inherent in these films. This work presents a pioneering approach to designing and realizing MP-VAN systems, and opens up opportunities for tailoring the complex three-dimensional (3D) physical properties and property coupling of VAN films towards diverse device applications.

All inorganic metal halide perovskite nanocrystals (NCs) have attracted much attention for their outstanding optoelectronic properties, which can be tuned by the composition, surface, size and morphology in nanoscale. Herein, we report the microfluidic synthesis of hollow CsPbBr₃ perovskite NCs through the nanoscale Kirkendall effect. The formation mechanism of the hollow structure (Kirkendall void) controlled by the temperature, flow rate, ratios of precursors and ligands was investigated. Compared with the solid CsPbBr₃ NCs of the same size, the hollow CsPbBr₃ NCs exhibit blue shifts in ultraviolet–visible (UV–vis) absorption and photoluminescence (PL) spectra, and remarkably longer PL average lifetime (~ 98.2 ns). Quantum confinement effect, inner surface induced additional trap states and lattice strain of the hollow CsPbBr₃ NCs were discussed in understanding their unique optoelectronic properties. The hollow CsPbBr₃ NC based photodetector exhibits an outstanding negative photoconductivity (NPC) detectivity of 8.9 × 10¹² Jones. They also show potentials in perovskite NC based photovoltaic and light emitting diodes (LEDs).

Elucidation the relationship between electrode potentials and heterogeneous electrocatalytic reactions has attracted widespread attention. Herein we construct the well-defined Mn single-atom (MnSA) catalyst with four N-coordination through a simple thermal pyrolysis preparation method to investigate the electrode potential micro-environments effect on carbon dioxide reduction reactions (CO₂RR) and oxygen reduction reactions (ORR). MnSA catalysts generate higher CO production Faradaic efficiency of exceeding 90% at −0.9 V for CO₂RR and higher H₂O₂ yield from 0.1 to 0.6 V with excellent ORR activity. Density functional theory (DFT) calculations based on constant potential models were performed to study the mechanism of MnSA on CO₂RR. The thermodynamic energy barrier of CO₂RR is lowest at −0.9 V vs. reversible hydrogen electrode (RHE). Similar DFT calculations on the H₂O₂ yield of ORR showed that the H₂O₂ yield at 0.2 V was higher. This study provides a reasonable explanation for the role of electrode potential micro-environments.

Lithium-sulfur (Li-S) batteries hold the potential to revolutionize energy storage due to the high theoretical capacity and energy density. However, the commercialization process is seriously hindered by the rapid capacity decay and low utilization of sulfur, caused by the inevitable slow dynamics and the “shuttle effect”. The incorporation of metal-based electrocatalysts into sulfur cathodes shows promise in promoting the conversion of lithium polysulfides (LiPSs), reducing the “shuttle effect”, and enhancing cell kinetics and cycle life. Among these, Fe-based materials, characterized by environmental friendliness, low cost, abundant reserves, and high activity, are extensively used in sulfur cathode modification. This article reviews the advancements of Fe-based materials in enhancing Li-S batteries in recent years. Starting from single/multi-component Fe-based metal compounds and single/bimetallic atoms, the influence of different Fe coordination environments on the conversion mechanism of LiPSs is analyzed. It is hoped that this review and the proposed prospects can further stimulate the development and application of the Fe element in Li-S batteries in the future.

Electrical modulation of luminescence is significant to modern light-emitting devices. Monolayer transition metal dichalcogenides are emerging direct-bandgap luminescent materials with unique excitonic properties, and the multiple exciton complexes provide new opportunities to modulate the property of luminescence in atomically thin semiconductors. Here, we report an electrical control of exciton emission in the oscillator strength and spatial distribution of excitons in a monolayer WS₂. Effective modulation of excitonic emission intensity with a degree of modulation of ~ 92% has been demonstrated by an electric field at room temperature. The spatial carrier redistribution tuned by a lateral electric field results in distinct excitonic emission patterns by design. The modulation approach to exciton oscillator strength and distribution provides an efficient way to investigate the exciton diffusion dynamics and to construct electrically tunable optoelectronic devices.