Nanoscale Horizons最新文献

In the field of electromagnetic interference (EMI) shielding with materials based on highly porous constructs, such as foams, cryogels, aerogels and xerogels, a significant challenge lies in designing structures that primarily absorb rather than reflect incident electromagnetic waves (EMWs). This goal necessitates a dual focus on the electrical conductivity and the internal porosity of the given porous material. To explore these issues, we fabricated various graphene oxide (GO)-based cryogels by molding, emulsion templating, chemically-induced gelation, freeze-casting, and liquid-in-liquid streaming. Following thermal annealing to enhance electrical conductivity for effective EMI shielding, we assessed the physicochemical, mechanical and structural characteristics of these cryogels. Notably, the cryogels exhibited distinct EMI shielding behaviors, varying significantly in terms of primary shielding mechanisms and overall shielding effectiveness (SE_T). For example, chemically-crosslinked cryogels, which showed the highest electrical conductivity, predominantly reflected EMWs, achieving a reflectance of approximately 70% and a SE_T of 43.2 dB. In contrast, worm-like cryogels, despite having a similar SE_T of 42.9 dB, displayed a unique absorption-dominant shielding mechanism. This was attributed to their multi-scale porosities and numerous internal interfaces, which significantly enhanced their ability to absorb EMWs, reflected in an absorbance of 54.7%. Through these experiments, our aim is to provide key heuristic rules for the structural design of EMI shields.

Increasing the InN content in the In_xGa_1−xN compound is paramount for optoelectronic applications. It has been demonstrated in homogeneous nanowires or deliberately grown nanowire heterostructures. Here, we present spontaneous core–shell In_xGa_1−xN nanowires grown by molecular beam epitaxy on Si substrates at 625 °C. These heterostructures have a high InN fraction in the cores around 0.4 and sharp interfaces, and exhibit bright photoluminescence at 650 nm. The surprising effect of material separation is attributed to the periodically changing environment for instantaneous growth of single monolayers on top of nanowires. Due to a smaller collection length of N adatoms, each monolayer nucleates under a balanced V/III ratio, but then continues under highly group III rich conditions. As a result, the miscibility gap is suppressed in the cores but remains in the shells. These results provide a simple method for obtaining high-quality InGaN heterostructures emitting in the extended wavelength range.

Intermetallic compound (IMC) catalysts have garnered significant attention due to their unique surface and electronic properties, which can lead to enhanced catalytic performance compared to traditional monometallic catalysts. However, developing IMC materials as high-performance catalysts has been hindered by the inherent complexity of synthesizing nanoparticles with well-defined bulk and surface compositions. Achieving precise control over the composition of supported bimetallic IMC catalysts, especially those with high surface area and stability, has proven challenging. This review provides a comprehensive overview of the recent progress in developing supported IMC catalysts. We first examine the various synthetic approaches that have been explored to prepare supported IMC nanoparticles with phase-pure bulk structures and tailored surface compositions. Key factors influencing the formation kinetics and compositional control of these materials are discussed in detail. Then the strategies for manipulating the surface composition of supported IMCs are delved into. Applications of high-performance supported IMCs in important reactions such as selective hydrogenation, reforming, dehydrogenation, and deoxygenation are comprehensively reviewed, showcasing the unique advantages offered by these materials. Finally, the prevailing research challenges associated with supported IMCs are identified, including the need for a better understanding of the composition–property relationships and the development of scalable synthesis methods. The prospects for the practical implementation of these versatile catalysts in industrial processes are also highlighted, underscoring the importance of continued research in this field.

Semiconducting single-wall carbon nanotubes (SWCNTs) are a promising material platform for near-infrared in vivo imaging, optical sensing, and single-photon emission at telecommunication wavelengths. The functionalization of SWCNTs with luminescent defects can lead to significantly enhanced photoluminescence (PL) properties due to efficient trapping of highly mobile excitons and red-shifted emission from these trap states. Among the most studied luminescent defect types are oxygen and aryl defects that have largely similar optical properties. So far, no direct comparison between SWCNTs functionalized with oxygen and aryl defects under identical conditions has been performed. Here, we employ a combination of spectroscopic techniques to quantify the number of defects, their distribution along the nanotubes and thus their exciton trapping efficiencies. The different slopes of Raman D/G⁺ ratios versus calculated defect densities from PL quantum yield measurements indicate substantial dissimilarities between oxygen and aryl defects. Supported by statistical analysis of single-nanotube PL spectra at cryogenic temperatures they reveal clustering of oxygen defects. The clustering of 2–3 oxygen defects, which act as a single exciton trap, occurs irrespective of the functionalization method and thus enables the use of simple equations to determine the density of oxygen defects and defect clusters in SWCNTs based on standard Raman spectroscopy. The presented analytical approach is a versatile and sensitive tool to study defect distribution and clustering in SWCNTs and can be applied to any new functionalization method.

In-sensor computing has gained attention as a solution to overcome the von Neumann computing bottlenecks inherent in conventional sensory systems. This attention is due to the ability of sensor elements to directly extract meaningful information from external signals, thereby simplifying complex data. The advantage of in-sensor computing can be maximized with the sampling principle of a restricted Boltzmann machine (RBM) to extract significant features. In this study, a stochastic photo-responsive neuron is developed using a TiN/In–Ga–Zn–O/TiN optoelectronic memristor and an Ag/HfO₂/Pt threshold-switching memristor, which can be configured as an input neuron in an in-sensor RBM. It demonstrates a sigmoidal switching probability depending on light intensity. The stochastic properties allow for the simultaneous exploration of various neuron states within the network, making identifying optimal features in complex images easier. Based on semi-empirical simulations, high recognition accuracies of 90.9% and 95.5% are achieved using handwritten digit and face image datasets, respectively. In addition, the in-sensor RBM effectively reconstructs abnormal face images, indicating that integrating in-sensor computing with probabilistic neural networks can lead to reliable and efficient image recognition under unpredictable real-world conditions.

Understanding the mechanisms underlying viral entry is crucial for controlling viral diseases. In this study, we investigated the interactions between reovirus and Nogo-receptor 1 (NgR1), a key mediator of reovirus entry into the host central nervous system. NgR1 exhibits a unique bivalent interaction with the reovirus capsid, specifically binding at the interface between adjacent heterohexamers arranged in a precise structural pattern on the curved virus surface. Using single-molecule techniques, we explored for the first time how the capsid molecular architecture and receptor polymorphism influence virus binding. We compared the binding affinities of human and mouse NgR1 to reovirus μ1/σ3 proteins in their isolated form, self-assembled in 2D capsid patches, and within the native 3D viral topology. Our results underscore the essential role of the concave side of NgR1 and emphasize that the spatial organization and curvature of the virus are critical determinants of the stability of the reovirus–NgR1 complex. This study highlights the importance of characterizing interactions in physiologically relevant spatial configurations, providing precise insights into virus–host interactions and opening new avenues for therapeutic interventions against viral infections.

Correction for ‘Enhancing the chemotherapeutic efficacy of platinum prodrug nanoparticles and inhibiting cancer metastasis by targeting iron homeostasis’ by Fang Ding et al., Nanoscale Horiz., 2020, 5, 999–1015, https://doi.org/10.1039/D0NH00148A.

Colloidal quantum dots (QDs) are highly promising for display technologies due to their distinctive optical characteristics, such as tunable emission wavelengths, narrow emission spectra, and superb photoluminescence quantum yields. Over the last decade, both academic and industrial research have substantially advanced quantum dot light-emitting diode (QLED) technology, primarily through the development of higher-quality QDs and more refined device structures. A key element of these advancements includes progress in the electron transport layer (ETL) technology, with metal oxide (MO) nanoparticles (NPs) like ZnO and ZnMgO emerging as superior choices due to their robust performance. Nevertheless, scalability challenges, such as particle agglomeration and positive aging, have prompted research into organic semiconductors that match the performance of MO NPs. This review aims to provide a detailed examination and comprehensive understanding of recent advances and challenges in ETLs based on both MO NPs and organic semiconductors, guiding future commercialization efforts for QLEDs.

Recently, pyrene-based covalent organic frameworks (PyCOFs) have aroused great interest because the large planar structure of the pyrene unit could effectively enhance the interlayer π–π interaction and promote the separation and migration of carriers, significantly improving the crystallinity and photoelectrical properties of PyCOFs. Since the first PyCOF-containing boroxate linkage was reported in 2008 by the Yaghi group, many PyCOFs with different kinds of linkages have been reported, exhibiting great potential applications in different fields such as adsorption/separation, chemical sensing, catalysis, energy storage, etc. However, as far as we know, the reviews related to PyCOFs are rare, although PyCOFs have been widely reported to show promising applications. Thus, it is right time and important for us to systematically summarize the research advance in PyCOFs, including the synthesis with different linkages and applications. Moreover, the prospects and obstacles facing the development of PyCOFs are discussed. We hope that this review will provide new insights into PyCOFs that can be explored for more attractive functions or applications.

We studied the exciton delocalization of indodicarbocyanine 5 dye derivative (Cy5-R) heterodimers templated by a DNA Holliday junction (HJ), which was quantified by the exciton hopping parameter J_m,n. These dyes were modified at the 5 and 5′ positions of indole rings with substituent (R) H, Cl, tBu, Peg, and hexyloxy (Hex) groups that exhibit different bulkiness and electron-withdrawing/donating capacities. The substituents tune the physical properties of the dyes, such as hydrophobicity (log P) and solvent-accessible surface area (SASA). We tuned the J_m,n of heterodimers by attaching two Cy5-Rs in adjacent and transverse positions along the DNA-HJ. Adjacent heterodimers exhibited smaller J_m,n compared to transverse heterodimers, and some adjacent heterodimers displayed a mixture of H- and J-like aggregates. Most heterodimers exhibited J_m,n values within the ranges of the corresponding homodimers, but some heterodimers displayed synergistic exciton delocalization that resulted in larger J_m,n compared to their homodimers. We then investigated how chemically distinct Cy5-R conjugated to DNA can interact to create delocalized excitons. We determined that heterodimers involving Cy5-H and Cy5-Cl and a dye with larger substituents (bulky substituents and large SASA) such as Cy5-Peg, Cy5-Hex, and Cy5-tBu resulted in larger J_m,n. The combination provides steric hindrance that optimizes co-facial packing (bulky Cy5-R) with a smaller footprint (small SASA) that maximizes proximity. The results of this study lay a groundwork for rationally optimizing the exciton delocalization in dye aggregates for developing next-generation technologies based on optimized exciton transfer efficiency such as quantum information systems and biomedicine.