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Graded-Index Fluoropolymer Antireflection Coatings for Invisible Plastic Optics
摘要： Plastic optics are used in an ever-expanding range of applications and yet a durable, high performance antireflection (AR) coating remains elusive for this material class. Here, we introduce a sacrificial porogen approach to produce ultralow refractive index nanoporous fluoropolymer AR coatings via thermal co-evaporation of Teflon AF and the small molecule N,N′-Bis(3-methylphenyl)-N,N′-diphenylbenzidine (NPD). Using this approach, we demonstrate a five-layer, step-graded AR coating that reduces the solar spectrum-averaged (400 < λ < 2000 nm) reflectance of acrylic plastic to <0.5% for incidence angles up to 40° and withstands over three months of outdoor rooftop exposure with minimal degradation. A trilayer coating optimized for the visible range yields luminous reflectivity down to ~0.1%, effectively rendering double-side coated acrylic plastic invisible under room lighting conditions. Strong adhesion to most optical plastics, an outstanding combination of mechanical, chemical, and environmental durability, and compatibility with commercial vacuum coating systems should enable this AR technology to find widespread practical use.
关键词： gradient-index,polymer optics,sacrificial porogen,antireflection,nanoporous
更新于2025-09-23 15:23:52
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Easy preparation of nanoporous Ge/Cu3Ge composite and its high performances towards lithium storage
摘要： Nanoporous Ge/Cu3Ge composite is fabricated simply through selective dealloying of GeCuAl precursor alloy in dilute alkaline solution. The as-made Ge/Cu3Ge is characterized by three dimensional (3D) bicontinuous network nanostructure which comprises of substantial nanoscale pore voids and ligaments. Owing to the 3D porous architecture and the introduction of well-conductive Cu3Ge, the lithium storage performances of Ge are dramatically enhanced in terms of higher cycling stability and superior rate performance. Nanoporous Ge/Cu3Ge anode delivers steady capacities above 1000 mA h g-1 upon cycling for 70 loops at 400 mA g-1. In particular, after 300 cycles at the high rate of 3200 mA g-1 the capacity retention for Ge/Cu3Ge is able to reach a maximum of 99.3%. On the contrary, the pure nanoporous Ge encounters severe capacity decay. In view of the outstanding energy storage performances and easy preparation, nanoporous Ge/Cu3Ge exhibits great application potential as an advanced anode in lithium storage related technologies.
关键词： dealloying,anode,lithium ion batteries,nanoporous,germanium
更新于2025-09-23 15:23:52
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Mutated Human P-Selectin Glycoprotein Ligand-1 and Viral Protein-1 of Enterovirus 71 Interactions on Au Nanoplasmonic Substrate for Specific Recognition by Surface-Enhanced Raman Spectroscopy
摘要： Protein tyrosine sulfation is a common post-translational modification that stimulates intercellular or extracellular protein-protein interactions and is responsible for various important biological processes, including coagulation, inflammation, and virus infections. Recently, human P-selectin glycoprotein ligand-1 (PSGL-1) has been shown to serve as a functional receptor for enterovirus 71 (EV71). It has been proposed that the capsid viral protein VP1 of EV71 is directly involved in this specific interaction with sulfated or mutated PSGL-1. Surface-enhanced Raman spectroscopy (SERS) is used to distinguish PSGL-1 and VP1 interactions on an Au nanoporous substrate and identify specific VP1 interaction positions of tyrosine residue sites (46, 48, and 51). The three tyrosine sites in PSGL-1 were replaced by phenylalanine (F), as determined using SERS. A strong phenylalanine SERS signal was obtained in three regions of the mutated protein on the nanoporous substrate. The mutated protein positions at (51F) and (48F, 51F) produced a strong SERS peak at 1599–1666 cm?1, which could be related to a binding with the mutated protein and anti-sulfotyrosine interactions on the nanoporous substrate. A strong SERS effect of the mutated protein and VP1 interactions appeared at (48F), (51F), and (46F, 48F). In these positions, there was less interaction with VP1, as indicated by a strong phenylalanine signal from the mutated protein.
关键词： viral protein 1,P-selectin glycoprotein ligand-1,surface-enhanced Raman spectroscopy,nanoporous,phenylalanine
更新于2025-09-23 15:21:01
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Fabrication and optoelectronic properties of Ga2O3/Eu epitaxial films on nanoporous GaN distributed Bragg reflectors
摘要： Nanoporous GaN distributed Bragg re?ectors (DBRs) with a high re?ectivity (* 92%), which was fabricated via a doping selective electrochemical etching process, were used to deposit Eu-doped b-Ga2O3 ?lms by using pulsed layer deposition. Structural and chemical composition analyses indicated that the 900 (cid:3)C-annealed ?lm in air has the best crystalline quality and highest photo-luminescence (PL) ef?ciency. The epitaxial relationship between the b-Ga2O3: Eu ?lm and DBR mirror was Ga2O3 (201)kGaN (0001) with Ga2O3 [010]kGaN [1210]. Compared to the Eu:Ga2O3 ?lm on reference template, the 900 (cid:3)C-an-nealed ?lm on the DBR mirror presented a * 20-fold enhancement in the PL emission. The performance enhancement was attributed to light-coupling enhancement of the buried DBR mirror. Because of the good electrical properties of the annealed ?lms, the fabricated DBR substrates pave the way for devel-oping a range of rare-earth-doped Ga2O3 optoelectronic devices.
关键词： Ga2O3/Eu,optoelectronic properties,pulsed layer deposition,distributed Bragg re?ectors,nanoporous GaN
更新于2025-09-23 15:21:01
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Fluorescent Properties of Gd-Doped Zno Nanonporous Networks & Its Application in Optical Biosensing
摘要： This research presents a study of the fluorescent properties of new materials based on gadolinium-doped zinc oxide nanoporous networks obtained by sol gel method on the surface of microcrystalline silicon. The effect of co-doping of different concentrations of Gd ions on the emission properties of ZnO nanoparticles has been investigated. Emissions of such biomolecules as protein, amino acids and porphyrin and its detection limits were studied for the purpose of practical application of Gd-doped ZnO nanonporous networks as an element of an optical biosensor technology.
关键词： sol-gel method,nanoporous networks,optical biosensing,fluorescent properties,Gd-doped ZnO
更新于2025-09-23 15:21:01
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<i>(Invited)</i> Electrochemical Formation of Nanoporous Indium Phosphide in KOH Electrolytes
摘要： Anodization of highly doped n-InP in KOH can result in a nanoporous sub-surface layer. Pores originate from surface pits and an isolated porous domain is initially formed beneath each pit. Domains are separated from the surface by a thin non-porous layer and each is connected to the electrolyte by its pit. Pores emanate along the <111>A directions to form truncated tetrahedral domains. We propose a three-step model of electrochemical pore formation: (1) hole generation at pore tips, (2) hole diffusion and (3) electrochemical oxidation of the semiconductor to form etch products. Step 1 determines the overall etch rate. However, if the kinetics of Step 3 are slow relative to Step 2, then etching can occur at preferred crystallographic sites leading to pore propagation in preferential directions. Pore width decreases with increasing anodization temperature and with increasing KOH concentration up to 9 mol dm-3, above which it decreases. At low current densities pores have sharp tips and triangular cross-sections; at higher current densities, the pore tips and cross-sections become more rounded while the pore width decreases. These observations are explained by the three-step model.
关键词： electrochemical formation,nanoporous,pore propagation,indium phosphide,KOH electrolytes
更新于2025-09-23 15:21:01
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Nanoconfined water vapour as a probe to evaluate plasmonic heating
摘要： Engineering the photothermal effect in plasmonic materials is of paramount importance for many applications such as cancer therapy, chemical synthesis, cold catalysis and more recently for metasurfaces. Evaluation of plasmonic heating at the nanoscale is challenging and generally requires sophisticated equipments and/or temperature-sensitive probes such as fluorescent molecules or materials. Here we propose to use water vapor as probe to evaluate the local heating around plasmonic nanoparticles. We demonstrated the concept for the case of a plasmonic colloidal film composed by a bi-modal nanoporosity. In particular we exploit the thermal and light water liquid-vapor phase transitions taking place into the nanoporous medium that can be triggered by external stimulus such as heating or irradiation to obtain structural and optical variations in the films. Estimation of the local temperature was then obtained by using spectroscopic ellipsometry acquired by a multimodal chamber. More generally, this method offer a simple and general approach to determine local temperature that only requires a nanoporous material and water vapor, such as environmental humidity. In addition this approach can be further generalized to other materials, vapor molecules or optical technique.
关键词： local temperature measurement,spectroscopic ellipsometry,water vapor,nanoporous materials,plasmonic heating
更新于2025-09-23 15:19:57
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Plasmonic-induced overgrowth of amorphous molybdenum sulfide on nanoporous gold: An ambient synthesis method of hybrid nanoparticles with enhanced electrocatalytic activity
摘要： Hybrid materials of earth abundant transition metal dichalcogenides and noble metal nanoparticles, such as molybdenum sulfide (MoSx) and gold nanoparticles, exhibit synergistic effects that can enhance electrocatalytic reactions. However, most current hybrid MoSx-gold synthesis requires an energy intensive heat source of >500 ○C or chemical plating to achieve deposition of MoSx on the gold surface. Herein, we demonstrate the direct overgrowth of MoSx over colloidal nanoporous gold (NPG), conducted feasibly under ambient conditions, to form hybrid particles with enhanced electrocatalytic performance toward hydrogen evolution reaction. Our strategy exploits the localized surface plasmon resonance-mediated photothermal heating of NPG to achieve >230 ○C surface temperature, which induces the decomposition of the (NH4)2MoS4 precursor and direct overgrowth of MoSx over NPG. By tuning the concentration ratio between the precursor and NPG, the amount of MoSx particles deposited can be systematically controlled from 0.5% to 2% of the Mo/(Au + Mo) ratio. Importantly, we find that the hybrid particles exhibit higher bridging and an apical S to terminal S atomic ratio than pure molybdenum sulfide, which gives rise to their enhanced electrocatalytic performance for hydrogen evolution reaction. We demonstrate that hybrid MoSx-NPG exhibits >30 mV lower onset potential and a 1.7-fold lower Tafel slope as compared to pure MoSx. Our methodology provides an energy- and cost-efficient synthesis pathway, which can be extended to the synthesis of various functional hybrid structures with unique properties for catalysis and sensing applications.
关键词： molybdenum sulfide,electrocatalytic activity,nanoporous gold,hydrogen evolution reaction,plasmonic
更新于2025-09-23 15:19:57
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Optimization of structural and optical properties of nanoporous silicon substrate for thin layer transfer application
摘要： A study on optical and structural properties of nanoporous silicon is presented in this paper. The samples were prepared by electrochemical etching a heavily boron doped silicon wafer in a hydrofluoric acid electrolyte and flowed by in-situ sintering in ultra-high vacuum chemical vapor deposition reactor (UHVCVD) under hydrogen atmosphere at high temperature varied between 900 and 1100 °C. The structural and morphological properties were carried out using atomic force microscopy (AFM), scanning electronic microscopy (SEM) and high resolution transmission electronic microscopy (HRTEM). The optical properties were performed using the photoluminescence Spectroscopy (PL), Time Resolved Photoluminescence (TRPL), RAMAN spectroscopy and Fourier-transform infrared spectroscopy (FT-IR). It is shown that the in-situ heating at 900 °C desorbs the native oxide from the porous layer and closes the pores forming a continuous defects-free surface at the top of porous layer. The process allows obtaining stable porous layer with enhanced structural and optical properties and also tailoring the morphological properties and the visible optical emission. This paper aims at a comprehensive determination of the physical properties of sintered porous silicon, in particular, its structural and optical properties.
关键词： structural properties,optical properties,nanoporous silicon,thin layer transfer,sintering
更新于2025-09-23 15:19:57
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Anodic Formation of Nanoporous Indium Phosphide in KOH Electrolytes: Effects of Temperature and Concentration
摘要： Anodization of n-InP electrodes was carried out over a range of temperatures and KOH concentrations. Scanning electron microscopy showed <111>A aligned pore growth with pore width decreasing as the temperature was increased. This variation is explained in terms of the relative rates of electrochemical reaction and hole diffusion and supports the three-step model proposed earlier. As temperature is increased, both the areal density and width of surface pits decrease resulting in a large increase in the current density through the pits. This explains an observed decrease in porous layer thickness: pits sustain mass transport at the necessary rate for a shorter time before precipitation of etch products blocks the pores. As the concentration of KOH is increased, both pore width and layer thickness decrease to minima at ～9 mol dm?3 after which they again increase. This variation of pore width is also explained by the three-step model and the variation in layer thickness is explained by mass transport effects. Layer porosity follows a similar trend to pore width, further supporting the three-step model. A transition from porous layer formation to planar etching is observed below 2 mol dm?3 KOH, and this is also explained by the three-step model.
关键词： concentration,three-step model,indium phosphide,anodization,nanoporous,KOH,temperature
更新于2025-09-19 17:15:36