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.
Significant efforts have been directed towards the preparation and application of porous hierarchically structured materials owing to their large surface area, rich active sites, and enhanced mass transport and diffusion. In this study, a simple and cost-effective method for the carbon quantum dot (CQD)-induced assembly of two-dimensional ultrathin Ni(OH)2 nanosheets into a three-dimensional (3D) porous hierarchical structure was developed. The electrostatic forces between the CQDs and cations drove the self-assembly of the 3D CQDs/Ni(OH)2 hierarchical structures. As a new type of structure-directing agent, the CQDs played dual roles in tuning the morphology of the products and improving the supercapacitor performance. The multilevel CQDs/Ni(OH)2 micro-nanostructures had a large specific surface area and rich porosity. Owing to their unique structures and the conductivity of the CQDs, an optimized asymmetric supercapacitor using the CQDs/Ni(OH)2 exhibited a maximum specific capacity of 161.3 F·g–1 and a high energy density of 57.4 Wh·kg–1. This study introduces a potential method for the fabrication of many other 3D hierarchical structures with great potential for applications in various fields.
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.
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.
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.
The development of photocatalysts that can effectively harvest visible light is essential for advances in high-efficiency solar-driven hydrogen generation. Herein, we synthesized water soluble CuInS2 (CIS) and Cu-In-Zn-S (CIZS) quantum dots (QDs) by using one-pot aqueous method. The CIZS QDs are well passivated by glutathione ligands and are highly stable in aqueous conditions. We subsequently applied these QDs as a light harvesting material for photocatalytic hydrogen generation. Unlike most small band gap materials that show extremely low efficiency, these new QDs display remarkable energy conversion efficiency in the visible and near-infrared regions. The external quantum efficiency at 650 nm is ～1.5%, which, to the best of our knowledge, is the highest value achieved until now in the near-infrared region.
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.
Cyclic penta-twinned noble metal nanocrystals exhibit promising properties due to their unique geometric and electronic structures. However, the controlled synthesis of cyclic penta-twinned nanostructures, especially of noble metals with a high cohesive energy (e.g., Rh), is very difficult, and the corresponding growth mechanism is not fully understood. Herein, we report a facile one-pot hydrothermal approach for the synthesis of cyclic penta-twinned Rh icosahedral nanocrystals. It was found that apart from regulating the surface free energy by changing the concentration or category of the capping agents, the solvent might influence the adsorption ability of the surfactant on the Rh crystal surface, which results in a change in the surface free energy and thus allows the formation of Rh cyclic penta-twinned nanostructures. In addition, due to their unique electronic and geometric structures, the Rh icosahedral nanocrystals exhibit superior catalytic activity and stability for the electrooxidation of ethanol as compared to single-crystal Rh tetrahedral nanocrystals and commercial Rh black.
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.
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.
With their unique optical properties associated with the excitation of surface plasmons, metal nanoparticles (NPs) have been used in optical sensors and devices. The organization of these NPs into arrays can induce coupling effects to engineer new optical responses. In particular, lattice plasmon resonances (LPRs), which arise from coherent interactions and coupling among NPs in periodic arrays, have shown great promise for realizing narrow linewidths, angle-dependent dispersions, and high wavelength tunability of optical spectra. By engineering the materials, shapes, sizes, and spatial arrangements of NPs within arrays, one can tune the LPR-based spectral responses and electromagnetic field distributions to deliver a multitude of improvements, including a high figure-of-merit, superior light–matter interaction, and multiband operation. In this review, we discuss recent progress in designing and applying new metal nanostructures for LPR-based applications. We conclude this review with our perspective on the future opportunities and challenges of LPR-based devices.
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.
