A thermal emitter composed of a frequency-selective surface metamaterial layer and a hexagonal boron nitride-encapsulated graphene filament is demonstrated. The broadband thermal emission of the metamaterial (consisting of ring resonators) was tailored into two discrete bands, and the measured reflection and emission spectra agreed well with the simulation results. The high modulation frequencies that can be obtained in these devices, coupled with their operation in air, confirm their feasibility for use in applications such as gas sensing.
This paper offers a comprehensive overview on the role of nanostructures in the development of advanced anode materials for application in both lithium and sodium-ion batteries. In particular, this review highlights the differences between the two chemistries, the critical effect of nanosize on the electrode performance, as well as the routes to exploit the inherent potential of nanostructures to achieve high specific energy at the anode, enhance the rate capability, and obtain a long cycle life. Furthermore, it gives an overview of nanostructured sodium- and lithium-based anode materials, and presents a critical analysis of the advantages and issues associated with the use of nanotechnology.
In this paper, we demonstrate that for colloidal CdSe/CdS nanoplatelets, a rectangular shape induces emission asymmetry, in terms of both polarization and emission patterns. Polarimetry and emission pattern analyses are combined to provide information on the orientation of the transition dipoles involved in the nanoplatelet emission. It is shown that for rectangular nanoplatelets, the emission is polarized and the emission patterns are anisotropic, whereas they remain nonpolarized and isotropic for square nanoplatelets. This can be appropriately described by the dielectric antenna effect induced by the elongated shape of the rectangular platelet.
Sodium-ion batteries have received remarkable attention as next-generation high-performance electrochemical energy storage devices because of their cost effectiveness and the broad geographical distribution of sodium. As a critical component of sodium-ion batteries, anode materials, especially nanostructured anodes, have a significant effect on the electrochemical performance of sodium-ion batteries. Recent research indicates that phosphorus and metal phosphides show great promise as anode candidates for sodium-ion batteries because of their low cost and relatively high theoretical gravimetric and volumetric specific capacities. In this review, we systematically summarize recent research progress on state-of-the-art nanostructured phosphorus and phosphides, including the synthetic strategies, Na-storage mechanisms, and the relationship between the nanostructure and electrochemical performance. Moreover, we present an overview of future challenges and opportunities based on current developments.
The wetting properties of an electrode surface are of significant importance to the performance of electrochemical devices because electron transfer occurs at the electrode/electrolyte interface. Described in this paper is a low-cost metal oxide electrocatalyst (CuO)-based high-performance sensing device using an enzyme electrode with a solid/liquid/air triphase interface in which the oxygen level is constant and sufficiently high. We apply the sensing device to detect glucose, a model test analyte, and demonstrate a linear dynamic range up to 50 mM, which is about 25 times higher than that obtained using a traditional enzyme electrode with a solid/liquid diphase interface. Moreover, we show that sensing devices based on a triphase assaying interface are insensitive to the significant oxygen level fluctuation in the analyte solution.
Solid polymer electrolytes are light-weight, flexible, and non-flammable and provide a feasible solution to the safety issues facing lithium-ion batteries through the replacement of organic liquid electrolytes. Substantial research efforts have been devoted to achieving the next generation of solid-state polymer lithium batteries. Herein, we provide a review of the development of solid polymer electrolytes and provide comprehensive insights into emerging developments. In particular, we discuss the different molecular structures of the solid polymer matrices, including polyether, polyester, polyacrylonitrile, and polysiloxane, and their interfacial compatibility with lithium, as well as the factors that govern the properties of the polymer electrolytes. The discussion aims to give perspective to allow the strategic design of state-of-the-art solid polymer electrolytes, and we hope it will provide clear guidance for the exploration of high-performance lithium batteries.
Understanding how small molecules interface with amyloid fibrils at the nanoscale is of importance for developing therapeutic treatments against amyloid-based diseases. Here, we show for the first time that human islet amyloid polypeptides (IAPP) in the fibrillar form are polymorphic, ambidextrous, and possess multiple periodicities. Upon interfacing with the small molecule epigallocatechin gallate (EGCG), IAPP aggregation was rendered off-pathway and assumed a form with soft and disordered clusters, while mature IAPP fibrils displayed kinks and branching but conserved the twisted fibril morphology. These nanoscale phenomena resulted from competitive interactions between EGCG and the IAPP amyloidogenic region, as well as end capping of the fibrils by the small molecule. This information is crucial in delineating IAPP toxicity implicated in type 2 diabetes and for developing new inhibitors against amyloidogenesis.
In this study, a potentially universal new strategy is reported for the large-scale, low-cost fabrication of visible-light-active highly ordered heteronanostructures based on the spontaneous photoelectric-field-enhancement effect inherent in pyramidal morphology. The hierarchical vertically oriented arrayed structures comprise an active molecular co-catalyst at the apex of a visible-light-active large band gap semiconductor for low-cost solar water splitting in a neutral aqueous medium without the use of a sacrificial agent.
By combining ab initio calculations and experiments, we demonstrate how the band gap of the transition metal trichalcogenide TiS3 can be modified by inducing tensile or compressive strain. In addition, using our calculations, we predicted that the material would exhibit a transition from a direct to an indirect band gap upon application of a compressive strain in the direction of easy electrical transport. The ability to control the band gap and its nature could have a significant impact on the use of TiS3 for optical applications. We go on to verify our prediction via optical absorption experiments that demonstrate a band gap increase of up to 9% (from 0.99 to 1.08 eV) upon application of tensile stress along the easy transport direction.
Electronic properties of stanene, the Sn counterpart of graphene are theoretically studied using first-principles simulations. The topological to trivial insulating phase transition induced by an out-of-plane electric field or by quantum confinement effects is predicted. The results highlight the potential to use stanene nanoribbons in gate-voltage controlled dissipationless spin-based devices and are used to set the minimal nanoribbon width for such devices, which is typically approximately 5 nm.
Molybdenum disulfide (MoS2), a promising non-precious electrocatalyst for the hydrogen evolution reaction with two-dimensional layered structure, has received increasing attention in recent years. Its electrocatalytic performance has been limited by the low active site content and poor conductivity. Herein, we report a facile and general ultrafast laser ablation method to synthesize MoS2 quantum dots (MS-QDs) for electrocatalytic HER with fully exposed active sites and highly enhanced conductivity. The MS-QDs were prepared by ultrafast laser ablation of the corresponding bulk material in aqueous solution, during which they were partially oxidized and formed defective structures. The as-prepared MS-QDs demonstrated high activity and stability in the electrocatalytic HER, owing to their very large surface area, defective structure, abundance of active sites, and high conductivity. The present MS-QDs can also find application in optics, sensing, energy storage, and conversion technologies.
A micropump induces the flow of its surrounding fluids and is extremely promising in a variety of applications such as chemical sensing or mass transportation. However, it is still challenging to manipulate its pumping direction. In this study, we examine a binary micropump based on perovskite and poly[(2-methoxy-5-ethylhexyloxy)-1,4-phenylenevinylene] (MEHPPV). The micropump is operational under the influence of light. Light exhibits significant versatility in controlling the pumping phenomenon of the micropump. It governs the start and stop and also regulates the velocity and directions. The direction control signifies immense opportunities for the development of micropumps with unprecedented pumping behaviors and functions (such as heartbeat-like pumping, rectification, and amplification). This makes them potentially useful in various fields. Hence, it is expected that the micropump reported in the current study could act as a key step towards the further development of more sophisticated micropumps for diverse applications.
We demonstrate an easy and scalable low-temperature process to convert porous ternary complex metal oxide nanoparticles from solution-synthesized core/shell metal oxide nanoparticles by thermal annealing. The final products demonstrate superior electrochemical properties with a large capacity and high stability during fast charging/discharging cycles for potential applications as advanced lithium-ion battery (LIB) electrode materials. In addition, a new breakdown mechanism was observed on these novel electrode materials.
Globally, cancer is growing at an alarming pace, which calls for development of more efficient cancer treatments. Conventional chemotherapy and radiotherapy have become crucial first-line clinical treatments for cancer. However, along with their wide usage, limited therapeutic effects, severe adverse reactions, unaffordable costs, and complicated operations lead to failures of these treatments. Moreover, the emergence of multidrug resistance inhibits the longtime usage of chemotherapeutics. One of the major causes of treatment failure is the insufficient sensitivity of cancer cells to therapeutic drugs or treatments. With the rigorous development of nanotechnology, tailored nanoparticles can efficiently sensitize malignant cells by inducing intracellular structural and functional changes, which could affect vital intracellular processes such as metabolism, signal conduction, proliferation, cell death as well as intracellular drug delivery. Here, we review recent advances in nanomaterial-assisted sensitization of oncotherapy, and challenges and strategies in the development of nanomedical approaches.
We have studied the magnetic and electrical transport properties of epitaxial NiAs-type CrTe thin films grown on SrTiO3(111) substrates. Unlike rectangle hysteresis loops obtained from magnetic measurements, we have identified intriguing extra bump/dip features from anomalous Hall experiments on the films with thicknesses less than 12 nm. This observed Hall anomaly is phenomenologically consistent with the occurrence of a topological Hall effect(THE) in chiral magnets with a skyrmion phase. Furthermore, the THE contribution can be tuned by the film thickness, showing the key contribution of asymmetric interfaces in stabilizing Néel-type skyrmions. Our work demonstrates that a CrTe thin film on SrTiO3(111) substrates is a good material candidate for studying real-space topological transport.
In this paper, we propose a novel construction of silicon nanowire (SiNW) negative-AND (NAND) logic gates on bendable plastic substrates and describe their electrical characteristics. The NAND logic gates with SiNW channels are capable of operating with a supply voltage as low as 0.8 V, with switching and standby power consumption of approximately 1.1 and 0.068 nW, respectively. Superior electrical characteristics of each SiNW transistor, including steep subthreshold slopes, high Ion/off ratio, and symmetrical threshold voltages, are the major factors that enable nanowatt-range power operation of the logic gates. Moreover, the mechanical bendability of the logic gates indicates that they have good and stable fatigue properties.
Li metal chemistry is a promising alternative with a much higher energy density than that of state-of-the-art Li-ion counterparts. However, significant challenges including safety issues and poor cyclability have severely impeded Li metal technology from becoming viable. In recent years, nanotechnologies have become increasingly important in materials design and fabrication for Li metal anodes, contributing to major progress in the field. In this review, we first introduce the main achievements in Li metal battery systems fulfilled by nanotechnologies, particularly regarding Li metal anode design and protection, ultrastrong separator engineering, safety monitoring, and smart functions. Next, we introduce recent studies on nanoscale Li nucleation/deposition. Finally, we discuss possible future research directions. We hope this review delivers an overall picture of the role of nanoscale approaches in the recent progress of Li metal battery technology and inspires more research in the future.
Silicene, the silicon counterpart of graphene, has been successfully grown on metallic substrates such as Ag(111), ZrB2(0001), and Ir(111) surfaces. However, characterization of its electronic structure is hampered by the metallic substrate. In addition, potential applications of silicene in nanoelectronic devices will require its growth on or integration with semiconducting and insulating substrates. We herein present a review of recent theoretical works regarding the interaction of silicene with non-metallic templates, distinguishing between the weak van-der-Waals-like interactions of silicene with, for example, layered metal (di)chalcogenides, and the stronger covalent bonding between silicene and, for example, ZnS surfaces. We then present a methodology to effectively compare the stability of diverse silicene structures using thermodynamics and molecular dynamics density functional theory calculations. Recent experimental results on the growth of silicene on MoS2 are also reported and compared to the theoretical predictions.
Sub-100 nm hollow carbon nanospheres with thin shells are highly desirable anode materials for energy storage applications. However, their synthesis remains a great challenge with conventional strategies. In this work, we demonstrate that hollow carbon nanospheres of unprecedentedly small sizes (down to ～32.5 nm and with thickness of ～3.9 nm) can be produced on a large scale by a templating process in a unique reverse micelle system. Reverse micelles enable a spatially confined Stöber process that produces uniform silica nanospheres with significantly reduced sizes compared with those from a conventional Stöber process, and a subsequent well-controlled sol–gel coating process with a resorcinol–formaldehyde resin on these silica nanospheres as a precursor of the hollow carbon nanospheres. Owing to the short diffusion length resulting from their hollow structure, as well as their small size and microporosity, these hollow carbon nanospheres show excellent capacity and cycling stability when used as anode materials for lithium/sodium-ion batteries.
Accurate regulation of cellular zinc signaling is imperative to decipher underlying zinc functions and develop new therapeutic agents. However, the ability to modulate zinc in a spatiotemporal manner remains elusive. We herein report an intelligent spiropyran-upconversion (SP-UCNPs) based nanosystem that enables near-infrared (NIR) light-controlled zinc release at precise times and locations. The magnitude of zinc release can be simply manipulated by varying the duration of NIR irradiation. Moreover, the utilization of NIR light not only showed little damage to cells but also significantly improved penetration depth. By evaluating activity of a model protein, phosphatase 2A, we further validated zinc signaling activation. Importantly, our strategy may be broadly applicable to other types of metal ions, like the ubiquitous second messenger calcium. More importantly, our strategy can potentially enable the precise control of specific signaling pathways of metal ions while minimizing cellular damage, facilitating the advanced manipulation of cellular dynamics.
