Electronic adjustment is one of the most commonly used strategies to improve the catalytic performance of heterogeneous catalysts. We prepared hexagonal ultrathin Pd nanosheets with edges modified by gold nanoparticles (Au@Pd nanosheets) using galvanic replacement method. By virtue of the electronic interactions between the Pd nanosheets and Au nanoparticles, the Au@Pd nanosheets exhibited excellent catalytic performances in the carbonylation of iodobenzene by carbon monoxide. The novel nanocomposites could be applied as model catalysts to explore electronic effects in catalysis.
Advanced permanent magnets based on rare-earth-free MnBi intermetallic alloys are considered energy-critical materials due to their applications in high temperature power electronics and green energy-related generators and motors, owing to their positive temperature coefficient of magnetic anisotropy. However, a direct method to achieve high saturation magnetization, without the significant loss of coercivity, is critical for attaining high performance MnBi magnets. Here, we demonstrate the synthesis and processing of magnetic nanocomposites, consisting of metal-redox MnBi nanoparticles and electro-spun FeCo nanowires. The composition ratio, processing dependent magnetism, and increased coercivity with increasing temperature, were studied in MnBi-FeCo nanocomposites. The magnetic performance of nanocomposites was dictated by interfacial coupling between magnetically hard MnBi and semi-hard FeCo nanowires, as well as the composition ratio and processing conditions. Solution processed MnBi-FeCo nanocomposites allow the potential for the development of high temperature and high performance rare-earth-free permanent magnets.
Multi-shelled CoFe2O4 hollow microspheres with a tunable number of layers (1–4) were successfully synthesized via a facile one-step method using cyclodextrin as a template, followed by calcination. The structural features, including the shell number and shell porosity, were controlled by adjusting the synthesis parameters to produce hollow spheres with excellent capacity and durability. This is a straightforward and general strategy for fabricating metal oxide or bimetallic metal oxide hollow microspheres with a tunable number of shells.
Immunotherapy is a promising strategy to inhibit cancer progression via activation of the immune system. In immunotherapy, adjuvants as immunologic stimulants or delivery systems play a critical role in inducing the antitumor immune response and decreasing the side effects of immune stimulants. Polymer nanoparticles have attracted increasing attention as an indispensable component of immunotherapy, owing to their favorable properties, such as excellent biocompatibility and biodegradability, flexible size, high activity as immune stimulants, large surface area for binding multivalent immune ligands, and high loading capacity for immune-related components. In cancer immunotherapy, polymer nanoparticles can protect cargo from the surrounding milieu, deliver the antigens and immunostimulatory molecules to antigen-presenting cells, or stimulate robust T cell response. This review summarizes the current advancements in polymer nanoparticle adjuvants for cancer immunotherapy and predicts their prospects in fundamental and clinical studies.
Artificial photosynthesis uses a catalyst to convert CO2 into valuable hydrocarbon products by cleaving the C=O bond. However, this technology is strongly limited by two issues, namely insufficient catalytic efficiency and complicated catalyst-fabrication processes. Herein, we report the development of a novel spray-drying photocatalyst-engineering process that addresses these two issues. Through one-step spray drying, with a residence time of 1.5 s, nanocomposites composed of tin oxide (SnO2) nanoparticles and edge-oxidized graphene oxide (eo-GO) sheets were fabricated without post-treatment. These nanocomposites exhibited 28-fold and five-fold enhancements in photocatalytic efficiency during CO2 reduction compared to SnO2 and commercialized TiO2 (P25), respectively, after irradiation with simulated sunlight for 4 h. This scalable approach, based on short residence times and facile equipment setup, promotes the practical application of artificial photosynthesis through the potential mass production of efficient photocatalysts.
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.
Bacterial infection has continued to be a leading cause of death or disability worldwide because of antibiotic resistance. Antibiotic agents specific to certain taxa of bacteria, i.e., narrow-spectrum antibiotics, have become useful because they can kill bacteria without resulting in broad-spectrum drug resistance. In this study, we describe a series of antibiotics based on combining gold nanoparticles (AuNPs) with aminosaccharides, even though these AuNPs or aminosaccharides by themselves are ineffective against any bacteria. The AuNP-based multivalent aminosaccharides can effectively and selectively inhibit the growth of Gram-positive bacteria (including drug-resistant superbacteria). In particular, aminosaccharide-modified AuNPs are effective against methicillin-resistant Staphylococcus aureus (MRSA), a particularly hard-to-treat strain. This report carves out a way to explore antibiotics by combining AuNPs and an aminosaccharide as multivalent nanostructures, neither of which by itself is effective as an antibiotic.
Collaborative enhancements from surface plasmons (SPs) and whispering-gallery modes (WGMs) can induce intense near-field effects with high spatial localization around the surface of a semiconducting material. One can construct a highly efficient hybrid microcavity using semiconducting materials through resonant coupling between SPs and WGMs. Hexagonal ZnO micro-/nanostructures, which have been employed as natural WGM microcavities for ultraviolet (UV) lasing, can be used as ideal platforms to construct such hybrid microcavities. Here, we comprehensively review the recent efforts for improving lasing performance by resonant coupling between SPs and WGMs. Traditional SPs originating from various metals as well as novel SPs originating from atomic layers such as graphene are considered. Moreover, we discuss the mechanism of light-matter interactions beyond the improvements in lasing performance.
We report a rationally designed one-pot method for the facile synthesis of Pd concave nanocubes in an aqueous solution at room temperature by manipulating the reduction kinetics through the selection of a proper combination of a salt precursor (PdBr42–) and reductant (sodium ascorbate). Our kinetic analysis demonstrates that, through this selection, the nucleation and growth of Pd nanocrystals could be effectively separated into two kinetic regimes involving distinctive reduction pathways: i) solution reduction for the initial formation of single-crystal seeds and ii) surface reduction for the formation of concave nanocrystals via autocatalytic growth from the single-crystal seeds. The suppressed surface diffusion at room temperature, when coupled with the capping effect of bromide ions, ultimately leads to the formation of concave nanocubes with an asymmetric shape and high-index facets, whose synthesis would otherwise require multiple steps and the use of elevated temperatures.
Bottom-up synthesis of graphene nanoribbons (GNRs) by surface-assisted polymerization and cyclodehydrogenation of specifically designed precursor monomers has been shown to yield precise edges and doping. Here we use a precursor monomer containing sulfur atoms to fabricate nanostructures on a Au(111) surface at different annealing temperatures. The nanostructures have distinct configurations, varying from sulfur-doped polymers to sulfur-doped chevron-type GNRs (CGNRs) and, finally, pristine graphene nanoribbons with specific edges of periodic five-member carbon rings. Non-contact atomic force microscopy provides clear evidence for the cleavage of C–S bonds and formation of pristine CGNRs at elevated annealing temperatures. First-principles calculations show that the CGNRs exhibit negative differential resistance.
The size and density of Ag nanoparticles on n-layer MoS2 exhibit thicknessdependent behavior. The size and density of these particles increased and decreased, respectively, with increasing layer number (n) of n-layer MoS2. Furthermore, the surface-enhanced Raman scattering (SERS) of Ag on this substrate was observed. The enhancement factor of this scattering varied with the thickness of MoS2. The mechanisms governing the aforementioned thickness dependences are proposed and discussed.
A triboelectric nanogenerator (TENG) and an electromagnetic generator (EMG) were hybridized to harvest the human mechanical energy. By an effective conjunction of triboelectrification and electromagnetic induction, the hybridized nanogenerator with a radius of 2 cm and height of 1.2 cm could charge a 1,000 μF capacitor to 5.09 V after 100 cycles of vibration. This mini-sized hybrid nanogenerator could then be embedded in shoes to serve as an energy cell. Typical outdoor applications—including driving with a Global Positioning System (GPS) device, charging a Li-ion battery and a cell phone—were successfully demonstrated, suggesting its potential application in smart wearable electronics and future suits of soldiers.
Copper sulfide (Cu7S4) nanoparticles coated with an ultra-high payload (~5.0 × 107 fluorine atoms per particle) of fluorinated ligands (oleylamine functionalized 3,5-bis(trifluoromethyl)benzaldehyde, 19FOAm) exhibited a single intense 19F magnetic resonance (MR) signal and efficient near infrared photothermal performance in water medium. In vivo assessment revealed strong 19F MR signals at cancerous lesions and effective inhibition of tumor growth after photothermal treatment, indicating the great potential of these fabricated nanoprobes for simultaneous 19F MR imaging and photothermal therapy.
To achieve better control of the formation of silver sulfide (Ag2S) nanoparticles, ultrasmall Ag nanoclusters protected by thiolate ligands (Ag44(SR)30 and Ag16(GSH)9) are used as precursors, which, via delicate chemistry, can be readily converted to monodisperse Ag2S nanoparticles with controllable sizes (4–16 nm) and switchable solvent affinity (between aqueous and organic solvents). This new synthetic protocol makes use of the atomic monodispersity and rich surface chemistry of Ag nanoclusters and a novel two-phase protocol design, which results in a well-controlled reaction environment for the formation of Ag2S nanoparticles.
We demonstrate a facile and effective approach to significantly improve the photoluminescence of bulk MoS2 via laser thinning followed by gold particle decoration. Upon laser thinning of exfoliated bulk MoS2, photoluminescence emerges from the laser-thinned region. After further treatment with an AuCl3 solution, gold particles self-assemble on the laser-thinned region and thick edges, further increasing the fluorescence of bulk MoS2 28 times and the Raman response 3 times. Such fluorescence enhancement can be attributed to both surface plasmon resonance and p-type doping induced by gold particles. The combination of laser thinning and AuCl3 treatment enables the functionalization of bulk MoS2 for optoelectronic applications. It can also provide a viable strategy for mask-free and area-selective p-type doping on single MoS2 flakes.
Coordination polymer particles (CPPs) with a high degree of porosity and multi-functional reaction sites are promising for diverse applications. The integration of open sites favorable for the post-modification of CPPs presents a unique opportunity for the rational design of inorganic materials with target-oriented functions. Herein, we report a shape-controllable synthetic protocol for zinc-based coordination polymer nanocubes (Zn-CPNs). In the synthesis, 2,6-bis[(4-carboxyanilino)carbonyl] pyridine ([N3]) ligand is employed as an efficient shape-directing modulator to control the size and shape of Zn-CPNs. More importantly, the [N3] ligand provides metal binding sites suitable for the decoration of other functional metals such as copper ions. The copper-modified Zn-CPNs (Cu_Zn-CPNs) show good activities in a heterogeneous catalytic reaction.
Developing highly efficient and durable catalysts for future electrochemical and energy applications is one of the main subjects of current studies in renewable energy generation. In the past several years, researchers have developed Pt-based alloy electrocatalyst nanomaterials that exhibit promising electrocatalytic properties for various electrochemical applications. The efficient structural and morphological control of Pt-based alloy materials plays a decisive role in achieving these enhanced electrocatalytic properties. The present review article emphasizes the recent progress and important developments in the synthesis and electrocatalytic applications of Pt-group-based nanodendrite materials. The following review will help the exploration and development of better catalysts for practical applications and aims to elucidate the nanodendrite structure of Pt-group metals.
Sandwich structured graphene-wrapped FeS-graphene nanoribbons (G@FeS-GNRs) were developed. In this composite, FeS nanoparticles were sandwiched between graphene and graphene nanoribbons. When used as anodes in lithium ion batteries (LIBs), the G@FeS-GNR composite demonstrated an outstanding electrochemical performance. This composite showed high reversible capacity, good rate performance, and enhanced cycling stability owing to the synergy between the electrically conductive graphene, graphene nanoribbons, and FeS. The design concept developed here opens up a new avenue for constructing anodes with improved electrochemical stability for LIBs.
Despite the excellent merits of lead perovskite solar cells, their instability and toxicity still present a bottleneck for practical applications. Bismuth perovskite has emerged as a candidate for photovoltaic (PV) applications, because it not only has a low toxicity but is also stable in air. However, the power conversion efficiency (PCE) remains an unsolved problem. We performed band gap tuning experiments to improve the efficiency. The absorption of ABi3I10 structure films was extended within the visible region, and the optical band gap was decreased considerably compared to that for Cs3Bi2I9. Furthermore, we explained the correlation between the structure and the optical properties via a first-principles study. A device employing CsBi3I10 as a photoactive layer exhibits a PCE of 1.51% and an excellent ambient stability over 30 days.
With superior biocompatibility and unique magnetic properties, iron-based nanoparticles (IBNP) are commonly encapsulated in cells and extracellular vesicles (EV) to allow for magnetic force controlled drug delivery and non-invasive tracking. Based on their natural source and similar morphology, we classify both cells and EVs as being natural lipid encapsulations (NLEs), distinguishing them from synthetic liposomes. Both their imaging contrast and drug effects are dominated by the amount of iron encapsulated in each NLE, demonstrating the importance of magnetic labeling efficiency. It is known that the membranes function as barriers to ensure that substances pass in and out in an orderly manner. The most important issue in increasing the cellular uptake of IBNPs is the interaction between the NLE membrane and IBNPs, which has been found to be affected by properties of the IBNPs as well as NLE heterogeneity. Two aspects are important for effective magnetic labelling: First, how to effectively drive membrane wrapping of the nanoparticles into the NLEs, and second, how to balance biosafety and nanoparticle uptake. In this review, we will provide a systematic overview of the magnetic labeling of NLEs with IBNPs. This article provides a summary of the applications of magnetically labeled NLEs and the labeling methods used for IBNPs. The review also analyzes the role of IBNPs physicochemical properties, especially their magnetic properties, and the heterogeneity of NLEs in the internalization pathway. At the same time, the future development of magnetically labeled NLEs is also discussed.
