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Self-assembled indium nanostructures formation on InSe (0001) surface
摘要： The surfaces of 2D layered crystals are one among most perspective templates for self-assembling of metal nanostructures due to the dewetting. The initial InSe (0001) surface as topological template was characterized by means of scanning tunneling microscopy/spectroscopy (STM/STS) and low electron energy diffraction. InSe (0001) surface used in the process of formation of nanostructures found to be a template covered with array of triangular-shaped cites. The results of STM/STS studies on the formation of indium nanostructures on (0001) surface of InSe layered semiconductor crystal are presented. Indium was thermally deposited on structurally perfect InSe crystal cleavages obtained in situ. Geometrically heterogeneous (in height) initial (0001) InSe surface is used to activate the dewetting phenomenon in a manner that leads to the formation of 0D triangular-shaped nucleus of deposited indium nanostructures. STS acquired spatially averaged I–V curves changes their dependence from semiconductor one to almost metallic due to dewetting process. Moreover, the spatial arrangement of formed indium nanostructures is powered by hexagonal lattice symmetry of InSe surface on macroscale.
关键词： Hetero nanostructures,Nanostructures template-directed assembly,Layered crystals,Scanning tunneling microscopy/spectroscopy,Indium selenide,Low energy electron diffraction
更新于2025-09-23 15:21:01
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Application of Periodical Nanostructures in Thin Metal Film for Near Infrared Multispectral Filters
摘要： Surface plasmonic nanostructures with cross-shaped-hole array in metal thin films are studied for multispectral filters, which cover visible to near-infrared wavelengths. Surface plasmons are induced from incident wave by the periodic arrays of nanostructures of the metal thin film, and then localized surface plasmon polaritons oscillate in the cavity, which is formed by two surfaces of metals through near-field excitation. The transmission spectra of light through these nanostructures are investigated with the finite-difference time-domain method; our simulations show that the features of the hole, and the periods of the array along with other parameters are critical to the optical spectral performance. The optical characterizations of our fabrications of these nanostructures milled by focused ion beam demonstrated very similar results of transmission spectra of simulation results. The simulations demonstrate he optical performance of the metal nanostructures, it is possible to obtain desired multispectral filters by programming parameters of those plasmonic nanostructures.
关键词： Nanostructures,Multispectral filters,Metallic plasmonic nanostructures
更新于2025-09-23 15:21:01
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Orientation Effects on Plasmonic Heating of Near-Infrared Colloidal Gold Nanostructures
摘要： Photothermal therapy assisted by plasmonic nanostructure relies on the absorption of light energy by the metallic nanoparticle. The manifestation of a rational use of plasmonic-assisted superficial laser thermal therapy procedures requires the analyses of the thermoplasmonic behavior of colloidal nanostructures in random orientation. A quantitative analysis of orientation effect on optically heating metallic nanostructures still unrevealed. Here, we evaluate the thermal properties of metallic nanoparticles (SiO2/Au core-shell particles, Au nanotriangles, Au nanorods, and Au nanocages) irradiated by polarized light. We perform 3D full-wave field analysis to compare absorption properties and temperature rise of these nanoparticles as a function of the nanostructure orientation with respect to applied field polarization. The analysis shows a major variation in joule number of asymmetrical nanostructures (up to 50%) due to orientation effects, which may limit its performance on colloidal photothermal applications. In contrast, the high degree of rotational symmetry of core-shell nanoparticles and nanocages provide greater potential in thermal-assisted phototherapy applications, as their absorption is largely independent (less than 2%) of their orientation in colloid. Our computational results establish new insights for the use of gold nanocages, as a high performance plasmonic structure for thermal applications with colloidal samples.
关键词： Joule number,Photothermal therapy,Gold nanostructures,Thermo-plasmonics
更新于2025-09-23 15:21:01
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1D/2D WO3 nanostructure coupled with nanoparticulate CuO cocatalyst for enhancing solar-driven CO2 photoreduction: The impact of the crystal facet
摘要： Photocatalytic reduction of CO2 into solar fuels is regarded as one of the most promising approaches to address the issues of global warming and the energy crisis. The promotion of spatial charge separation and transfer through crystal facet engineering could be conducive to improved photocatalytic activity. In this study, one-dimensional (1D) WO3 nanowires with a {110} dominant facet (WO3-110) and two-dimensional (2D) WO3 nanosheets with a {001} dominant facet (WO3-001) coupled with CuO nanoparticles are fabricated by a facile method and used for CO2 photoreduction. Its composition and structural characterizations suggest that the WO3-CuO hybrid features good contact between the WO3 and CuO nanostructures. Under light irradiation, the WO3 and WO3-CuO nanostructures are able to photoreduce CO2 into CH4. Notably, the prepared WO3-CuO nanohybrids with different exposed facets show improved CO2 reduction capability compared to pure WO3 and CuO. The heterojunction interface between the WO3 photocatalyst and the CuO cocatalyst through p-n contact can facilitate electron-hole pair separation and accordingly results in enhanced photocatalytic performance. With the assistance of the CuO cocatalyst, the {110} facet WO3-CuO hybrid displays superior photoreduction capability compared to the {001} facet WO3-CuO, which is attributed to the difference in the crystal facets in the heterostructure. The {110} facet WO3 nanowires have a more negative conduction band edge, contributing to the higher reduction capacity of this sample. On the other hand, it is shown that faster charge carrier transfer efficiency would enable more photoinduced electrons to participate in CO2 photoreduction, especially with the involvement of the nanoparticulate CuO cocatalyst. This work provides guidance for designing a hetero-photocatalyst-cocatalyst system through crystal facet engineering.
关键词： WO3-CuO composite,CO2 Photoreduction,1D/2D WO3 nanostructures,heterojunction,crystal facet impact
更新于2025-09-23 15:21:01
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A Novel Nanorod Self-Assembled WO <sub/>3</sub> ?· H <sub/>2</sub> O Spherical Structure: Preparation and Flexible Gas Sensor
摘要： In this work, a novel WO3·H2O spherical structure which was self-assembled by nanorods was achieved by using hydrothermal method. A comprehensive growth mechanism was proposed to explain the formation of three different type nanostructures. Flexible gas sensors were successfully fabricated based on such unique nanostructures. We found that these nanorods and nanoparticle’s self-assembled spherical structure showed excellent gas response to ammonia. This result may provide great benefit potential to further study for the preparation and gas performance of such self-assembled structure of WO3·H2O.
关键词： WO3·H2O,Nanostructures,Self-Assembly,Hydrothermal Process,Gas-Sensing
更新于2025-09-23 15:21:01
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Bandgap engineering in CuO nanostructures: Dual-band, broadband, and UV-C photodetectors
摘要： In this work, the bandgap of CuO (p-type semiconductor) has been engineered from an indirect bandgap of (cid:2)1 eV to a direct bandgap of 4 eV just by tuning the nanostructure morphology and midgap defect states. The absorption in near-infrared (NIR) and visible regions is ordinarily suppressed by controlling the growth parameters. Considering the increasing scope and demand of varying spectral range (UV-C to NIR) photodetectors, the systematic variation of the available density of states (DOS) at a particular energy level in CuO nanostructures has been utilized to fabricate dual-band (250 nm and 900 nm), broadband (250 nm–900 nm), and UV-C (250 nm) photodetectors. The sensitivity and detectivity of the photodetector for broadband detectors were (cid:2)103 and 2.24 (cid:3) 1011 Jones for the wavelengths of 900 nm and 122 and 2.74 (cid:3) 1010 Jones for 250 nm wavelength light, respectively. The UV-C detector showed a sensitivity of 1.8 and a detectivity of 4 (cid:3) 109 Jones for 250 nm wavelength light. A plausible mechanism for the photoconduction has been proposed for explaining the device operation and the effect of variation in available DOS. The obtained photodetectors are the potential candidates for future optoelectronic applications.
关键词： Broadband photodetectors,Bandgap engineering,CuO nanostructures,Dual-band photodetectors,UV-C photodetectors
更新于2025-09-23 15:21:01
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Extremely Low Dark Current and Detection Range Extension of Ga2O3 UV Photodetector using Sn Alloyed Nanostructures
摘要： A unique metal-semiconductor-metal (MSM) photodetector has been fabricated using Sn incorporation in Ga2O3 forming SnxGa1-xO nanostructures (Ns) with platinum (Pt) metal as contacts. The mixed nanostructures (MNs) has been attributed to an increment in the detection range of UV (254 – 302 nm) with ultra-low dark current, hence a potential device in the field of long range deep-UV detector. SnxGa1-xO (Ns) are deposited on c-plane sapphire using low-pressure chemical vapour deposition (LPCVD). From the X-ray diffraction results, existence both SnxGa1-xO and tetragonal SnO2 MNs are confirmed. The XRD peak shifts in SnxGa1-xO is attributed to the integration of Sn with Ga forming SnxGa1-xO alloy with x to be ~7.3% determined from the Vegard’s law. The FESEM images show the thick diameter wire-shaped nanostructures. The absorption spectra show a trace of two absorption edges corresponding to both SnxGa1-xO and SnO2 Ns. Photo to dark current ratio (PDCR) of the fabricated photodetector is large (103) at 2 V bias with fast fall time of 0.18 s. The detector reveals self-powered behaviour also with PDCR > 104 at 0 V bias. The dark current is ultra-low (13 pA at 5 V) due to high barrier height of Pt and the UV detection range has been extended from 254 – 302 nm with a very small drop in PDCR owing to incorporation of Sn.
关键词： LPCVD,Nanostructures,Photodetector,Gallium Oxide
更新于2025-09-23 15:21:01
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Microwave-assisted synthesis of ZnO nanostructures for organic solar cell applications
摘要： In this work, a simple and efficient microwave-assisted hydrothermal method was adopted to synthesis zinc oxide nanostructures. Zinc acetate and hexamethylenetetramine were used as precursors. Various parameters involving synthesis conditions were attuned in order to achieve well-defined morphology. XRD peaks indicated the high crystallinity and hexagonal wurtzite structure of the prepared material. Field emission scanning electron microscopy revealed different morphology of the synthesized material. The prepared material can be used in organic solar cells, for effective dissociation of electron-hole pairs and thus enhancing photovoltaic performance.
关键词： Morphology,Organic solar cells,Microwave,Nanostructures,ZnO
更新于2025-09-23 15:21:01
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Sensitive and Direct DNA Mutation Detection by Surface-enhanced Raman Spectroscopy using Rational Designed and Tunable Plasmonic Nanostructures
摘要： Efficient DNA mutation-detection methods are required for diagnosis, personalized therapy development, and prognosis assessment for diseases such as cancer. To address this issue, we proposed a straightforward approach by combining active plasmonic nanostructures, surface enhanced Raman spectroscopy (SERS), and polymerase chain reaction (PCR), with a statistical tool to identify and classify BRAF wild type (WT) and V600E mutant genes. The nanostructures provide enhanced sensitivity, while PCR offers the high specificity towards target DNA. A series of positively charged plasmonic nanostructures including gold/silver nanospheres, nanoshells, nanoflowers and nanostars, were synthesized with a one-pot strategy and characterized. By changing the shape of nanostructures, we are able to vary the surface plasmon resonance from 551 nm to 693 nm. The gold/silver nanostar showed the highest SERS activity, which was employed for DNA mutation detection. We reproducibly analyzed as few as 100 copies of target DNA sequences using gold/silver nanostars, thus demonstrating the high sensitivity of the direct SERS detection. By means of statistical analysis (principal component analysis-linear discriminant analysis, PCA-LDA), this method was successfully applied to differentiate the WT and V600E mutant both from whole genome DNA (gDNA) lysed from cell line and from cell-free DNA (cfDNA) collected from cell culture media. We further proved that this assay is capable of specifically amplifying and accurately classifying a real plasma sample. Thus, this direct SERS strategy combined with the active plasmonic nanostructures has the potential for wide applications as an alternative tool for sensitively monitoring and evaluating clinical important nucleotide biomarkers.
关键词： PCR,statistical analysis,plasmonic nanostructures,surface-enhanced Raman spectroscopy,DNA mutation detection
更新于2025-09-23 15:21:01
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Periodic ZnO-Elevated Gold Dimer Nanostructures for Surface-Enhanced Raman Scattering Applications
摘要： The electron beam lithography-defined periodic ZnO-elevated gold dimer nanostructures for surface-enhanced Raman spectroscopy with strong electromagnetic field enhancements were fabricated in the present work. The ZnO nanorods (NRs) were grown on the patterned substrate using the hydrothermal process and Au dimers were deposited on the top surface of ZnO NRs, forming suspended gold dimers and providing plasmonic hot-spots with nanocavity effect. The effects of dimer radius, gap size and ZnO NR height on the dark-field scattering spectra and surface-enhanced Raman scattering (SERS) were investigated experimentally and theoretically. The SERS response was enhanced with increasing dimer radius and decreasing gap size. The SERS enhancement factor (EF) due to the localized surface plasmon resonance was calculated from simulation results. The calculated EF as a function of ZnO NR height showed the periodic trend of electric field intensity with the periodicity of about half of the exciting laser wavelength, and was in agreement with SERS measurements. Our hybrid substrates combining plasmonic nanocavity effect with charge transfer across the heterojunction denoted the potential candidate for SERS applications.
关键词： Plasmonics,Surface-Enhanced Raman Scattering,ZnO-Elevated Gold Dimer Nanostructures,Magnetic,Optical,and Hybrid Materials
更新于2025-09-23 15:21:01