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Binary Superlattices of Infrared Plasmonic and Excitonic Nanocrystals
摘要： Self-assembled superlattices of nanocrystals offer exceptional control over the coupling between nanocrystals, similar to how solid-state crystals tailor the bonding between atoms. By assembling nanocrystals of different properties (e.g., plasmonic, excitonic, dielectric, or magnetic), we can form a wealth of binary superlattice metamaterials with new functionalities. Here, we introduce infrared plasmonic Cu2?xS nanocrystals to the limited library of materials that have been successfully incorporated into binary superlattices. We are the first to create a variety of binary superlattices with large excitonic (PbS) nanocrystals and small plasmonic (Cu2?xS) nanocrystals, both resonant in the infrared. Then, by controlling the surface chemistry of large Cu2?xS nanocrystals, we produced structurally analogous superlattices of large Cu2?xS and small PbS nanocrystals. Transmission electron microscopy (TEM) and grazing-incidence small-angle X-ray scattering (GISAXS) were used to characterize both types of superlattices. Furthermore, our unique surface modification of the large Cu2?xS nanocrystals also prevented them from chemically quenching the photoluminescence of the PbS nanocrystals, which occurred when the PbS nanocrystals were mixed with unmodified Cu2?xS nanocrystals. These synthetic achievements create a set of binary superlattices that can be used to understand how infrared plasmonic and excitonic nanocrystals couple in a variety of symmetries and stoichiometries.
关键词： infrared quantum dots,nanocrystals,self-assembly,supracrystal,metamaterial,binary superlattice,grazing-incidence small-angle X-ray scattering (GISAXS)
更新于2025-09-23 15:21:01
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Reduced Graphene Oxide Aerogels with Uniformly Self-Assembled Polyaniline Nanosheets for Electromagnetic Absorption
摘要： Reduced Graphene Oxide (RGO)/polyaniline (PANI) composite aerogels (GPA) with uniformly distributed PANI nanosheets were prepared by a facile self-assembly way. The fabricated hybrids present a cross-linked three-dimensional(3D) porous network and RGO sheets were covered by PANI sheets with controlled content. The unique architecture efficiently reduced agglomeration of RGO and enhanced the conductive loss of the material to incident wave. Specifically, the GPA composite with 50 wt% PANI showed excellent electromagnetic wave absorption capacity, the largest reflection loss (RL) value reached -48 dB with fill loading of only 3% and the qualified bandwidth (RL ≤-10 dB) covered the entire Ku band (12-18 GHz). The study is expected to pave the way to prepare wide qualified bandwidth and lightweight graphene-based electromagnetic wave absorption hybrids with controlled microstructure.
关键词： conductive network,3D porous structure,electromagnetic wave absorption,self-assembly,light weight
更新于2025-09-23 15:21:01
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Ordered Mesoporous TiO <sub/>2</sub> Gyroids: Effects of Pore Architecture and Nb-Doping on Photocatalytic Hydrogen Evolution under UV and Visible Irradiation
摘要： Pure and Nb-doped TiO2 photocatalysts with highly ordered alternating gyroid architecture and well-controllable mesopore size of 15 nm via co-assembly of a poly(isoprene)-block-poly(styrene)-block-poly(ethylene oxide) block copolymer are synthesized. A combined effort by electron microscopy, X-ray scattering, photoluminescence, X-ray photoelectron spectroscopy, Raman spectroscopy, and density functional theory simulations reveals that the addition of small amounts of Nb results in the substitution of Ti4+ with isolated Nb5+ species that introduces inter-bandgap states, while at high concentrations, Nb prefers to cluster forming shallow trap states within the conduction band minimum of TiO2. The gyroidal photocatalysts are remarkably active toward hydrogen evolution under UV and visible light due to the open 3D network, where large mesopores ensure efficient pore diffusion and high photon harvesting. The gyroids yield unprecedented high evolution rates beyond 1000 μmol h?1 (per 10 mg catalyst), outperforming even the benchmark P25-TiO2 more than fivefold. Under UV light, the Nb-doping reduces the activity due to the introduction of charge recombination centers, while the activity in the visible triple upon incorporation is owed to a more efficient absorption due to inter-bandgap states. This unique pore architecture may further offer hitherto undiscovered optical benefits to photocatalysis, related to chiral and metamaterial-like behavior, which will stimulate further studies focusing on novel light–matter interactions.
关键词： photocatalysis,block copolymers,titanium dioxide,self-assembly
更新于2025-09-23 15:21:01
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Self-assembled monolayer film of concave star-shaped Au nanocrystals as highly efficient SERS substrates
摘要： In this work, various geometries of Au nanocrystals with sharp tips including decahedra, concave star, and spindle were synthesized through Ag underpotential deposition-dominated growth approach based on utilizing a novel type of Au nanoseed (i.e., pentatwinned Au nanospheres). These as-prepared Au nanocrystals exhibited a broad localized surface plasmon resonance (LSPR) tunability from visible to near-infrared region. Furthermore, we fabricated the monolayer film based on Au nanocrystals with different morphologies through liquid/liquid interface self-assembly technique, which displayed strong shape-dependent surface enhanced Raman scatting (SERS) performance. More significantly, concave star-shaped Au nanocrystals with ten sharp tips endowed them with 12-fold higher SERS enhancements than Au nanospheres, which was in line with the simulation results by finite difference time domain (FDTD) method. Our study provides a novel route for fabrication of Au nanocrystals with diversified structures, and the efficient SERS substrates have great prospect for the applications in ultrasensitive chemical and biological sensing.
关键词： Au nanocrystals,SERS,Self-assembly,LSPR,Underpotential deposition
更新于2025-09-23 15:21:01
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Tiled Monolayer Films of 2D Molybdenum Disulphide Nanoflakes Assembled at Liquid/Liquid Interfaces
摘要： Thin films of MoS2 bilayer nanoflakes, which are predominantly a single flake thick and in edge-to-edge contact, have been produced via self-assembled tiling at the planar interface between two immiscible liquids. Films of several square centimeters extent can be produced with total covered area approaching 90 % and over 70 % of the film covered by single flakes without overlap. Films produced through liquid/liquid assembly are shown to produce a lower uncovered area fraction and more uniform thickness when compared with films of similar areal coverage produced by the “top-down” techniques of spin coating and spray coating. Statistical analysis of flake coverage data, measured by AFM, shows that liquid/liquid assembly produces a distinctly different variation in film thickness than conventional “top-down” deposition. This supports the hypothesis that the 2D confinement of liquid/liquid assembly produces more uniform films. Demonstrator field-effect transistors (FETs) manufactured from the films exhibit mobility and on/off current ratios of 0.73 cm2 V-1 s-1 and 105 respectively; comparable to FETs of similar layout and CVD-grown or mechanically cleaved single crystal MoS2 channel material. This work demonstrates the use of liquid/liquid interfaces as a useful tool for self-assembly of high performance thin film devices made from dispersions of 2D materials.
关键词： self-assembly,2D materials,coverage,device fabrication,thin films,Poisson distribution
更新于2025-09-23 15:21:01
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Edge Enriched Self-assembly of Au Nanoparticles: Coffee-Ring Effect during Microcontact Printing via Agarose Stamps
摘要： Amino functionalized surfaces were selectively modified via the combination of a wet agarose stamping technique and microcontact printing technique. Because of the specific reaction environments and diffusion of HNO2 confined in agarose stamp, the reaction of amino groups in the edge of the strip pattern was much more intense than other areas. The modified amino groups in the edge areas show higher affinity to Au-NPs than other areas, consequently, edge enriched Au-NPs patterns were observed after the self-assembly of Au-NPs. A “cylindrical droplet” model, in a manner analogous to coffee-ring effect, was proposed to describe the diffusion of HNO2 from the bulk to the edge in agarose stamp. By using such density varied Au-NPs patterns as templates for the growth of ZnO nanorods, we observed high density of Au-NPs resulting in high density and highly (001) oriented ZnO nanorods. In contrast, sparse and non-oriented ZnO nanorods were grew on low density of Au-NPs areas. Our findings might open new routes for the fabrication of gradient patterns and extend applications of Au-NPs patterns in surface enhanced Raman scattering and catalysis.
关键词： coffee-ring effect,gradient patterns,microcontact printing,agarose stamp,self-assembly
更新于2025-09-23 15:21:01
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Fabrication cobalt-doped indium oxide/molybdenum disulfide ternary nanocomposite toward carbon monoxide gas sensing
摘要： This paper demonstrated a high-performance carbon monoxide (CO) gas sensor based on cobalt (Co)-doped indium oxide (In2O3) nanoparticles/molybdenum disulfide (MoS2) nanoflowers nanocomposite. Co-In2O3 nanoparticles were synthesized by a co-precipitation method, and flower-like MoS2 was prepared by one-step hydrothermal route. Layer-by-layer self-assembly technique was employed to fabricate Co-In2O3/MoS2 film sensor on an epoxy substrate with interdigital electrodes. Scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) were carried out to fully examine the morphology, microstructure, and elementary composition of the as-prepared samples. The CO-sensing characteristics of the Co-In2O3/MoS2 film sensor were systematically investigated under room temperature through exposing the sensor to various concentration of CO gas. The Co-In2O3/MoS2 sensor achieved high sensitivity, fast response/recovery speed, excellent repeatability and stable long-term stability. An approach of combining gas-sensing experiments with density-functional theory (DFT) simulation based on first-principle was used to further explore the CO-sensing mechanism of the Co-In2O3/MoS2 sensor. The Co2+ ion doping, and heterojunctions created at interfaces of Co-In2O3 and MoS2 were attributed to the high-performance CO sensing.
关键词： CO gas sensor,LbL self-assembly,molybdenum disulfide,first-principle theory,Co-doped indium oxide
更新于2025-09-23 15:21:01
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Plasmonic Janus Microspheres Created from Pickering Emulsion Drops
摘要： Metal nanostructures have been created in a film format to develop unique plasmonic properties. Here, well-defined metal nanostructures are designed on the surface of microspheres to provide plasmonic microgranules. As conventional techniques are inadequate for nanofabrication on spherical surfaces, photocurable emulsion drops with a regular array of silica particles are employed at the interface to create periodic nanostructures. The silica particles, originating from the dispersed phase, fully cover the interface by forming a non-close-packed hexagonal array after drop generation, and slowly protrude to the continuous phase during aging while their interparticle separation decreases. Therefore, hexagonal arrays of spherical dimples with controlled geometry and separation are created on the surface of microspheres by photocuring the drops and removing the particles. Directional deposition of either aluminum or gold results in a continuous film with a hexagonal array of holes on the outermost surface and isolated curved disks in dimples, which renders the hemisphere of microspheres plasmonically colored. The resonant wavelength is controlled by adjusting the aging time, metal thickness, and size of silica particles, providing various plasmonic colors. This granular format of the plasmonic Janus microspheres will open a new avenue of optical applications including active color pixels, optical barcodes, and microsensors.
关键词： Janus microspheres,self-assembly,colloids,Pickering emulsions,plasmonic colors
更新于2025-09-23 15:21:01
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Self-Assembly of Europium-Containing Polyoxometalates/Tetra- <i>n</i> -alkyl Ammonium with Enhanced Emission for Cu <sup>2+</sup> Detection
摘要： Lanthanide-containing polyoxometalates (POMs) can be used to detect various materials, but their luminescence in water has suffered enormous limitations due to the strong fluorescence quenching. Herein, to resolve this problem, three-dimensional nanoparticles built by mixed Weakley-type europium-containing POMs (Na9[EuW10O36]·32H2O, abbreviated to EuW10) and tetra-n-alkyl ammonium (TA) with enhanced fluorescent properties have been designed in aqueous solution using an ionic self-assembly (ISA) technique, which is mainly driven by the electrostatic interaction between EuW10 and TA. The morphology and fluorescent properties of the system as well as some influencing factors (alkyl chain length, amino group, and inorganic salt concentration) were systematically investigated. The results indicated that the fluorescent intensity of EuW10/tetramethylammonium bromide (TMAB) composite increased about 14 times, whereas the extent of increase of fluorescence for EuW10/tetraethylammonium bromide (TEAB) and EuW10/tetrabutylammonium bromide (TMAB) composites gradually decrease due to the bulkier steric hindrance of the longer alkyl chain. Besides, the luminescence of EuW10/TMAB nanoparticles is pH responsive, and the reversibility of their structures and luminescence can be realized upon the addition of NaOH/HCl. Moreover, the EuW10/TMAB system also shows great fluorescence-sensing behavior, which could detect Cu2+ with a detection limit of 0.15 μM. Our work provides a facile construction strategy for a functional fluorescent complex via POMs-based supramolecular self-assembly in aqueous solution, which will be further used in biomarkers and sensors.
关键词： Cu2+ detection,fluorescence enhancement,ionic self-assembly,lanthanide-containing polyoxometalates,pH-responsive
更新于2025-09-23 15:21:01
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Single molecule localisation microscopy reveals how HIV-1 Gag proteins sense membrane virus assembly sites in living host CD4 T cells
摘要： Monitoring virus assembly at the nanoscale in host cells remains a major challenge. Human immunodeficiency virus type 1 (HIV-1) components are addressed to the plasma membrane where they assemble to form spherical particles of 100 nm in diameter. Interestingly, HIV-1 Gag protein expression alone is sufficient to produce virus-like particles (VLPs) that resemble the immature virus. Here, we monitored VLP formation at the plasma membrane of host CD4+ T cells using a newly developed workflow allowing the analysis of long duration recordings of single-molecule Gag protein localisation and movement. Comparison of Gag assembling platforms in CD4+ T cells expressing wild type or assembly-defective Gag mutant proteins showed that VLP formation lasts roughly 15 minutes with an assembly time of 5 minutes. Trapping energy maps, built from membrane associated Gag protein movements, showed that one third of the assembling energy is due to direct Gag capsid-capsid interaction while the remaining two thirds require the nucleocapsid-RNA interactions. Finally, we show that the viral RNA genome does not increase the attraction of Gag at the membrane towards the assembling site but rather acts as a spatiotemporal coordinator of the membrane assembly process.
关键词： HIV-1,Gag protein,virus assembly,CD4+ T cells,single-molecule localisation microscopy
更新于2025-09-23 15:21:01