Nano Letters最新文献

Fast emitting polymeric scintillators are requested in advanced applications where high speed detectors with a large signal-to-noise ratio are needed. However, their low density implies a weak stopping power of high energy radiation and thus a limited light output and sensitivity. To enhance their performance, polymeric scintillators can be loaded with dense nanoparticles (NPs). We investigate the properties of a series of polymeric scintillators by means of photoluminescence and scintillation spectroscopy, comparing standard scintillators with a composite system loaded with dense hafnium dioxide (HfO₂) NPs. The nanocomposite shows a scintillation yield enhancement of +100% with an unchanged time response. We provide for the first time an interpretation of this effect, pointing out the local effect of NPs in the generation of emissive states upon interaction with ionizing radiation. The obtained results indicate that coupling fast conjugated emitters with optically inert dense NPs could lead to surpassing the actual limits of pure polymeric scintillators.

Full-dimensional spatial light modulation requires simultaneous, arbitrary, and independent manipulation of the spatial phase, amplitude, and polarization. This is crucial for leveraging the complete physical dimension resources of light. However, full-dimensional metamodulation can be challenging due to the need for multiple independent control factors. To address this challenge, here we propose parallel-tasking metasurfaces to enable full-dimensional spatial light metamodulation based fully on the geometric-phase concept. Indeed, the meta-atoms are divided into several subphases, each of which serves as an independent control factor to manipulate light phase, amplitude, and polarization through geometric phase, interference, and orthogonal polarization superposition, respectively. Therefore, the macroscopic group of meta-atoms leads to metasurfaces that can achieve broadband full-dimensional spatial light metamodulation, as demonstrated by various types of structured light generation. This approach paves the way to future wide applications of light manipulation enabled by full-dimensional spatial light metamodulation.

Recent years have seen a growing interest in zero-dimensional (0D) transport phenomena occurring across two-dimensional (2D) materials for their potential applications to nanopore technology such as ion separation and molecular sensing. Herein, we investigate ion transport through 1 nm-wide nanopores in Ti₃C₂ MXene using molecular dynamics simulations. The high polarity and fish-bone arrangement of the Ti₃C₂ MXene offer a built-in potential and an atomic-scale distortion to the nanopore, causing an adsorption preference for cations. Our observation of variable cation-specific ion selectivity and Coulomb blockade highlights the complex interplay between adsorption affinity and cation size. The cation-specific ion selectivity can induce both the ion current and electro-osmotic water transmission, which can be regulated by tailoring the ions' preferential pathways through electric field tilting. Our finding underscores the pivotal role of the atomic arrangement of MXenes in 0D ion transport and provides fundamental insight into the application of 2D material in nanopores-based technologies.

The simultaneous detection of the orbital angular momentum (OAM) and wavelength offers new opportunities for optical multiplexing. However, because of the dispersion of lens functions for Fourier transformation, the mode conversions at distinct wavelengths cannot be achieved in the same plane. Here we propose an ultracompact achromatic complementary metal oxide semiconductor (CMOS)-integrated OAM mode detector. Specifically, a spatial multiplexed scheme, randomly interleaving the phase distributions for distributing the superposed OAM modes into preset positions at distinct wavelengths, is presented. In addition, such a nanoprinted achromatic OAM detector featuring a microscale size and a short focal length can be integrated onto a CMOS chip. Consequently, the four-bit incident light beams at three discrete wavelengths (633, 532, and 488 nm) can be distinguished with a high degree of accuracy evaluated by the average standardized Euclidean distance of ∼0.75 between the analytical and target results. Our results showcase a miniaturized platform for achieving high-capacity information processing.

DNA hydrogel represents a potent material for crafting biological scaffolds, but the toolbox to systematically regulate the mechanical property is still limited. Herein, we have provided a strategy to tune the stiffness of DNA hydrogel through manipulating the rigidity of DNA modules. By introducing building blocks with higher molecular rigidity and proper connecting fashion, DNA hydrogel stiffness could be systematically elevated. These hydrogels showed excellent dynamic properties and biocompatibility, thus exhibiting great potential in three-dimensional (3D) cell culture. This study has offered a systematic method to explore the structure-property relationship, which may contribute to the development of more intelligent and personalized biomedical platforms.

Layered lithiated oxides are promising materials for next generation Li-ion battery cathode materials; however, instability during cycling results in poor performance over time compared to the high capacities theoretically possible with these materials. Here we report the characterizations of a Li_1.47Mn_0.57Al_0.13Fe_0.095Co_0.105Ni_0.095O_2.49 high-entropy layered oxide (HELO) with the Li₂MO₃ structure where M = Mn, Al, Fe, Co, and Ni. Using electron microscopy and X-ray spectroscopy, we identify a homogeneous Li₂MO₃ structure stabilized by the entropic contribution of oxygen vacancies. This defect-driven entropy would not be attainable in the LiMO₂ structure sometimes observed in similar materials as a secondary phase owing to the presence of fewer O sites and a 3+ oxidation state for the metal site; instead, a Li_2-γMO_3-δ is produced. Beyond Li₂MO₃, this defect-driven entropy approach to stabilizing novel compositions and phases can be applied to a wide array of future cathode materials including spinel and rock salt structures.

Mass photometry (MP) is a rapidly growing optical technique for label-free mass measurement of single biomolecules in solution. The underlying measurement principle provides numerous advantages over ensemble-based methods but has been limited to low analyte concentrations due to the need to uniquely and accurately quantify the binding of individual molecules to the measurement surface, which results in diffraction-limited spots. Here, we combine nanoparticle lithography with surface PEGylation to substantially lower surface binding, resulting in a 2 orders of magnitude improvement in the upper concentration limit associated with mass photometry. We demonstrate the facile tunability of degree of passivation, enabling measurements at increased analyte concentrations. These advances provide access to protein-protein interactions in the high nanomolar to low micromolar range, substantially expanding the application space of mass photometry.

N₂O is a dominant atmosphere pollutant, causing ozone depletion and global warming. Currently, electrochemical reduction of N₂O has gained increasing attention to remove N₂O, but its product is worthless N₂. Here, we propose a direct eight-electron (8e) pathway to electrochemically convert N₂O into NH₃. As a proof of concept, using density functional theory calculation, an Fe₂ double-atom catalyst (DAC) anchored by N-doped porous graphene (Fe₂@NG) was screened out to be the most active and selective catalyst for N₂O electroreduction toward NH₃ via the novel 8e pathway, which benefits from the unique bent N₂O adsorption configuration. Guided by theoretical prediction, Fe₂@NG DAC was fabricated experimentally, and it can achieve a high N₂O-to-NH₃ Faradaic efficiency of 77.8% with a large NH₃ yield rate of 2.9 mg h^-1 cm^-2 at -0.6 V vs RHE in a neutral electrolyte. Our study offers a feasible strategy to synthesize NH₃ from pollutant N₂O with simultaneous N₂O removal.

Molybdenum disulfide (MoS₂) is one of the most intriguing two-dimensional materials, and moreover, its single atomic defects can significantly alter the properties. These defects can be both imaged and engineered using spherical and chromatic aberration-corrected high-resolution transmission electron microscopy (C_C/C_S-corrected HRTEM). In a few-layer stack, several atoms are vertically aligned in one atomic column. Therefore, it is challenging to determine the positions of missing atoms and the damage cross-section, particularly in the not directly accessible middle layers. In this study, we introduce a technique for extracting subtle intensity differences in C_C/C_S-corrected HRTEM images. By exploiting the crystal structure of the material, our method discerns chalcogen vacancies even in the middle layer of trilayer MoS₂. We found that in trilayer MoS₂ the middle layer's damage cross-section is about ten times lower than that in the monolayer. Our findings could be essential for the application of few-layer MoS₂ in nanodevices.