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Fabrication, Modelling and Assessment of Hybrid 1-D Elastic Fabry Perot Microcavity for Mechanical Sensing Applications
摘要： 1-D multilayer dielectric films consisting of seven pairs of SiO2 and TiO2 alternating layers are deposited on a SiO2 substrate using the radio frequency sputtering technique. The thicknesses of the film layers are chosen to reflect the visible radiation around 650 nm. An elastic microcavity layer made of Polydimethylsiloxane was sandwiched between two Bragg reflectors. A fabrication process was then developed for elastic microcavity in order to tailor the thickness, establish the surface planarity and to increase reproducibility of the samples. Optical transmittance of the single Bragg reflector and the microcavity were both simulated and measured. A comparison between measurement data and Transfer Matrix Method calculations shows a favourable correlation. Furthermore, in order to assess the suitability of the microcavity as a force sensor, transmittance measurements were carried out as a function of the applied forces. The change in the elastic microcavity thickness due to applied forces resulted in cavity resonance peak shifts proportional to the applied forces.
关键词： Optical Characterization and Modelling,Silica and Titania,1D Elastic Photonic Crystal,Mechanical Sensor,RF sputtering,PDMS
更新于2025-09-23 15:22:29
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Effect of Transition Metal Oxide Doping (Cr, Co, V) in the Photocatalytic Activity of TiO2 for Congo Red Degradation under Visible Light
摘要： Comparative study of Cr, Co or V-doped TiO2 was carried out. The photocatalysts were synthesized via sol-gel method. The results indicated that the dopants of Cr, Co, and V induced anatase to rutile phase transition of TiO2 at different dopant amounts of 1, 4, 2 mol%, respectively. Besides that, the existence of dopant extended the absorption wavelength of TiO2 to visible light region, thus making it a visible-driven photocatalyst. The doped transition metal exhibited different oxidation states on the TiO2 surface. The prepared photocatalysts were tested over photodegradation of Congo Red. Amongst all, Cr-doped TiO2 (3 mol%) was the best photocatalyst attributed to the presence of 45% rutile phase, reduced band gap energy of 2.30 eV and formation of Cr6+, which acted as an electron scavenger to delay the hole-electron recombination.
关键词： photodegradation,congo red,transition metal oxide,Titania
更新于2025-09-23 15:22:29
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Sensitization of TiO <sub/>2</sub> by the symmetric cationic polymethine dye for the photocatalytic reduction of methylene blue
摘要： Using the spectral, electrochemical and energy transformation characteristics of the cationic polymethine dye (D) 2-[(1E)-1,3-butadienyl-]-1-(phenylmethyl)-benindolium borfluoride, it has been found that the dye can be applied as a highly efficient sensitizer of TiO2. An intensity of the initially narrow light adsorption band becomes wider and embraces practically entire visible and near IR zones as a result of application of the dye to the surface of TiO2. Due to this effect, a wider array of light quanta can potentially be involved in the photocatalytic transformations. Some new heterostructures (HS) of the type D/TiO2 have been developed and their photocatalytic activities were determined in the test reaction of reduction of methylene blue by formaldehyde for different dye contents and under various modes of irradiation. The schemes of the energy transformation initiated by the light with different wavelengths are proposed and discussed.
关键词： photocatalytic activity.,heterostructure,Cationic polymethine dye,titania,methylene blue,sensitizing
更新于2025-09-23 15:22:29
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Mechanistic Study on Facet-Dependent Deposition of Metal Nanoparticles on Decahedral-Shaped Anatase Titania Photocatalyst Particles
摘要： Facet-selective gold or platinum-nanoparticle deposition on decahedral-shaped anatase titania particles (DAPs) exposing {001} and {101} facets via photodeposition (PD) from metal-complex sources was reexamined using DAPs prepared with gas-phase reaction of titanium (IV) chloride and oxygen by quantitatively evaluating the area deposition density on {001} and {101} and comparing with the results of deposition from colloidal metal particles in the dark (CDD) or under photoirradiation (CDL). The observed facet selectivity, more or less {101} preferable, depended mainly on pH of the reaction suspensions and was almost non-selective at low pH regardless of the deposition method, PD or CDL, and the metal-source materials. Based on the results, the present authors propose that facet selectivity is attributable to surface charges (zeta potential) depending on the kind of facets, {001} and {101}, and pH of the reaction mixture and that this concept can explain the observed facet selectivity and possibly the reported facet selectivity without taking into account facet-selective reaction of photoexcited electrons and positive holes on {101} and {001} facets, respectively.
关键词： zeta potential,pH dependence,facet-selective reaction,facet-selective metal photodeposition,{001} and {101} facets,decahedral-shaped anatase titania particles
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE Micro Electro Mechanical Systems (MEMS) - Belfast (2018.1.21-2018.1.25)] 2018 IEEE Micro Electro Mechanical Systems (MEMS) - A novel approach to black titania fabrication via atomic layer deposition for energy storage
摘要： This work presents the first demonstration of atomic layer deposited (ALD) black titania (TiOx), to the best of our knowledge. By fabricating b-TiOx using ALD we have accomplished four distinct achievements: (1) development of a direct deposition method of b-TiOx, without need for deoxygenation annealing, as required by current fabrication processes; (2) the ability to deposit b-TiOx onto highly porous materials with ?ngstrom-level precision; (3) increased response to the solar spectrum over TiO2, as demonstrated by >10x improvement in detectable photocurrent when compared to TiO2; (4) >7x improvement in capacitance when comparing a b-TiOx supercapacitor to a TiO2 supercapacitor. As such, this work allows for more robust and precise black titania deposition, opening up new possibilities of devices based on b-TiOx.
关键词： atomic layer deposition,supercapacitor,energy storage,photocurrent,black titania
更新于2025-09-23 15:21:21
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Morphology of TiO2 Layers with a Well-Developed Acicular–Fibrous Structure in VT-20 Titanium
摘要： We have studied the effect of size factors of substrates on the formation of TiO2 layers with a well-developed acicular–fibrous structure on VT-20 titanium. The proposed technique allows a TiO2 layer with a large surface area to be produced by etching in a KOH solution (without using hydrothermal synthesis conditions), followed by heat treatment. The layers thus produced consist of fibers 20–100 nm in diameter and up to 1 μ m in length, which are strongly bonded to the substrate surface. Their phase composition is dominated by rutile. The fiber growth process is shown to be influenced by substrate etching and heat treatment conditions, weakly influenced by the curvature of the substrate, and independent of its dimensions.
关键词： large surface area,acicular structure,morphology,titania
更新于2025-09-23 15:21:21
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Sustainable Organic Dyes from Winemaking Lees for Photoelectrochemical Dye-Sensitized Solar Cells
摘要： During the last two decades, Dye Sensitized Solar Cells (DSSCs) have received a great deal of attention as a promising, low-cost alternative to conventional silicon photovoltaic devices. Natural dye molecules can be used as a sensitizer for their low cost, good light absorbance, easy preparation process, and biodegradability. In this study, dyes were obtained from wine lees, the last by-product of winemaking process, supplied by a venetian winery (Italy). Polyphenols, like tannins and anthocyanins, which were extracted from winemaking lees, were adsorbed on a nanostructured ordered mesoporous titanium dioxide, previously treated at different temperatures (400–600 °C). Both dyes and titania semiconductor samples were studied with different techniques. The tests were carried out on prototypes to evaluate the cell power and the photocurrent generated under simulated solar light irradiation. The obtained solar energy conversion efficiencies are comparable to those that were reported in literature by using organic dyes extracted from vegetables, fruits, and plants. It is significant that these dyes are largely available and cost effective, since recovered from a waste otherwise to be disposed of, opening up a perspective of feasibility for inexpensive and environmentally friendly dye solar cells to generate green electricity and transforming agri-food waste into a resource.
关键词： circular economy,organic dyes,titania nanoparticles,winemaking lees,DSSCs
更新于2025-09-23 15:21:01
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A novel kinetic model to estimate the agglomerate diameter formed by nano-sized Titania in emulsion region of AFBPR
摘要： To predict the agglomerate diameter formed by nano-sized Titania powders (P25) in emulsion region of annular fluidization bed photocatalytic reactor (AFBPR), a kinetic model was developed based on an assumption of a target molecule only reacts on the active site of an agglomerate in illumination field. The results indicated that the agglomerate diameter was a function of bed voidage and gas velocity for a given photocatalytic oxidation. It was obvious that the agglomerate diameter decreased with increasing bed voidage, and decreased along the heighten of fluidized bed, which were confirmed by the experimental results. The agglomerate size decreased with gas velocity increased, validated by the estimated data of force model. Finally, the veracity of kinetic model was validated by variation of gaseous compound types and their concentrations, which suggested that this kinetic model was feasible for photocatalytic oxidation of gaseous pollutants. This investigation highlights the novel method to describe the relationship between agglomerate diameter distribution formed in emulsion region of AFBPR and photocatalytic reactivity.
关键词： Kinetic model,Agglomerate,Bed voidage,Titania,Photocatalytic oxidation
更新于2025-09-23 15:21:01
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Efficient N, Fe Co-Doped TiO2 Active under Cost-Effective Visible LED Light: From Powders to Films
摘要： An eco-friendly photocatalytic coating, active under a cost-effective near-visible LED system, was synthesized without any calcination step for the removal of organic pollutants. Three types of doping (Fe, N and Fe + N), with different dopant/Ti molar ratios, were investigated and compared with undoped TiO2 and the commercial P25 photocatalyst. Nano-crystalline anatase-brookite particles were successfully produced with the aqueous sol-gel process, also at a larger scale. All samples displayed a higher visible absorption and specific surface area than P25. Photoactivity of the catalyst powders was evaluated through the degradation of p-nitrophenol in water under visible light (>400 nm). As intended, all samples were more performant than P25. The N-doping, the Fe-doping and their combination promoted the activity under visible light. Films, coated on three different substrates, were then compared. Finally, the photoactivity of a film, produced from the optimal N-Fe co-doped colloid, was evaluated on the degradation of (i) p-nitrophenol under UV-A light (365 nm) and (ii) rhodamine B under LED visible light (395 nm), and compared to undoped TiO2 film. The higher enhancement is obtained under the longer wavelength (395 nm). The possibility of producing photocatalytic films without any calcination step and active under low-energy LED light constitutes a step forward for an industrial development.
关键词： aqueous sol-gel process,Fe/N doping,LED visible light,titania,photocatalysis
更新于2025-09-23 15:21:01
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AIP Conference Proceedings [Author(s) 3RD INTERNATIONAL SCIENCES, TECHNOLOGY & ENGINEERING CONFERENCE (ISTEC) 2018 - MATERIAL CHEMISTRY - Penang, Malaysia (17–18 April 2018)] - Synthesis of gold nanoparticles (AuNPs) onto anodized titania nanotubes (TNTs) by spin coating technique
摘要： Gold nanoparticles (AuNPs) have received copious interests due to their unique properties such as small in size, reactive, high surface area and can be potentially applied in myriad fields including physics, chemistry, medicine and material sciences. However, the nanosized of gold particles makes them very reactive and undergo aggregation without protection. For that reason, supporting materials are introduced to prevent the aggregation of the AuNPs. In particular, metal oxide for example, titanium dioxide or titania nanotubes (TNTs) has been used as a support material because of its inertness, high porosity and great surface areas. Nevertheless, achieving precise control of attachment AuNPs on the TNTs substrate by conventional methods such as thermal evaporation and conservative heating are far from satisfactory. Herein, in this work, a new approach has been developed to synthesize controlled and uniformed attachment of AuNPs onto fabricated electrochemically-anodized TNTs by a spin coating technique. This preliminary work used different spin rate of 500, 1000 and 2000 revolutions per minute (rpm), following by heat treatment at 250 °C for 2 hours. The FESEM micrograph showed the anodized TNTs with good morphological structures were successfully fabricated at a voltage of 50 V in a mixture of ethylene glycol containing 0.5 wt. % ammonium fluoride solution, with an average nanotubes diameter of 150 nm. Meanwhile, the attachment of AuNPs on the fabricated TNTs has been effectively achieved at a higher spin rate of 2000 rpm and the EDX analysis confirmed the deposition of AuNPs over the TNTs. The AuNPs-TNTs also were tested for the catalytic reduction of p-nitrophenol (p-NP), in which is discussed shortly in this paper.
关键词： Gold nanoparticles,spin coating,titania nanotubes,electrochemical anodization
更新于2025-09-23 15:21:01