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Czerwiński M, del Olmo Martinez R, Michalska-Domańska M. Application of Anodic Titanium Oxide Modified with Silver Nanoparticles as a Substrate for Surface-Enhanced Raman Spectroscopy. MATERIALS (BASEL, SWITZERLAND) 2023; 16:5696. [PMID: 37629988 PMCID: PMC10456277 DOI: 10.3390/ma16165696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 08/10/2023] [Accepted: 08/14/2023] [Indexed: 08/27/2023]
Abstract
The formation of nanostructured anodic titanium oxide (ATO) layers was explored on pure titanium by conventional anodizing under two different operating conditions to form nanotube and nanopore morphologies. The ATO layers were successfully developed and showed optimal structural integrity after the annealing process conducted in the air atmosphere at 450 °C. The ATO nanopore film was thinner (1.2 +/- 0.3 μm) than the ATO nanotube layer (3.3 +/- 0.6 μm). Differences in internal pore diameter were also noticeable, i.e., 88 +/- 9 nm and 64 +/- 7 nm for ATO nanopore and nanotube morphology, respectively. The silver deposition on ATO was successfully carried out on both ATO morphologies by silver electrodeposition and Ag colloid deposition. The most homogeneous silver deposit was prepared by Ag electrodeposition on the ATO nanopores. Therefore, these samples were selected as potential surface-enhanced Raman spectroscopy (SERS) substrate, and evaluation using pyridine (aq.) as a testing analyte was conducted. The results revealed that the most intense SERS signal was registered for nanopore ATO/Ag substrate obtained by electrodeposition of silver on ATO by 2.5 min at 1 V from 0.05M AgNO3 (aq.) (analytical enhancement factor, AEF ~5.3 × 104) and 0.025 M AgNO3 (aq.) (AEF ~2.7 × 102). The current findings reveal a low-complexity and inexpensive synthesis of efficient SERS substrates, which allows modification of the substrate morphology by selecting the parameters of the synthesis process.
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Affiliation(s)
- Mateusz Czerwiński
- Institute of Optoelectronics, Military University of Technology, Kaliskiego 2, 00-908 Warsaw, Poland;
| | | | - Marta Michalska-Domańska
- Institute of Optoelectronics, Military University of Technology, Kaliskiego 2, 00-908 Warsaw, Poland;
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Simfroso K, Cabo SR, Unabia R, Britos A, Sokołowski P, Candidato R. Solution Precursor Plasma Spraying of TiO 2 Coatings Using a Catalyst-Free Precursor. MATERIALS (BASEL, SWITZERLAND) 2023; 16:1515. [PMID: 36837144 PMCID: PMC9959857 DOI: 10.3390/ma16041515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/08/2023] [Accepted: 02/08/2023] [Indexed: 06/18/2023]
Abstract
The microstructural characteristics and phase composition of solution precursor plasma-sprayed (SPPS) titania-based coatings using a catalyst-free precursor are reported in this work. An ethanol-based solution containing titanium isopropoxide was used to deposit TiO2 coatings. The thermal behavior of the solution precursor changed as its phase transformation temperature increased when the molar concentration was increased from 0.3 M to 0.6 M. Scanning electron micrographs showed that the surface of the coatings was composed of nano- and submicron-sized spherical particles (<1 μm) with sintered and melted particles. The cross-sections showed a porous structure using lower concentrations and dense coating formation with micropores using higher concentrations, with thicknesses of about 5 µm-8 µm. Moreover, the coatings when the number of spray passes was increased were 16 µm-20 µm thick, giving an average layer thickness of 0.6 µm deposited per spray pass in all cases. Phase analysis revealed the presence of both the anatase and rutile phases of TiO2 in coatings sprayed with various concentrations at various stand-off distances. More detailed discussion is presented with respect to the effects of the solution concentration, stand-off distance, and number of spray passes on the coating's phase composition and microstructure.
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Affiliation(s)
- Key Simfroso
- Department of Physics, College of Science and Mathematics, Mindanao State University-Iligan Institute of Technology (MSU-IIT), Andres Bonifacio Ave., Tibanga, Iligan City 9200, Philippines
- Premier Research Institute of Science and Mathematics (PRISM), Mindanao State University-Iligan Institute of Technology (MSU-IIT), Andres Bonifacio Ave., Tibanga, Iligan City 9200, Philippines
| | - Shena Ramyr Cabo
- Premier Research Institute of Science and Mathematics (PRISM), Mindanao State University-Iligan Institute of Technology (MSU-IIT), Andres Bonifacio Ave., Tibanga, Iligan City 9200, Philippines
| | - Romnick Unabia
- Premier Research Institute of Science and Mathematics (PRISM), Mindanao State University-Iligan Institute of Technology (MSU-IIT), Andres Bonifacio Ave., Tibanga, Iligan City 9200, Philippines
| | - Angelito Britos
- Department of Physics, College of Science and Mathematics, Mindanao State University-Iligan Institute of Technology (MSU-IIT), Andres Bonifacio Ave., Tibanga, Iligan City 9200, Philippines
- Premier Research Institute of Science and Mathematics (PRISM), Mindanao State University-Iligan Institute of Technology (MSU-IIT), Andres Bonifacio Ave., Tibanga, Iligan City 9200, Philippines
| | - Paweł Sokołowski
- Department of Metal Forming, Welding and Metrology, Faculty of Mechanical Engineering, Wrocław University of Science and Technology (WUST), Wybrzeże Stanisława Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Rolando Candidato
- Department of Physics, College of Science and Mathematics, Mindanao State University-Iligan Institute of Technology (MSU-IIT), Andres Bonifacio Ave., Tibanga, Iligan City 9200, Philippines
- Premier Research Institute of Science and Mathematics (PRISM), Mindanao State University-Iligan Institute of Technology (MSU-IIT), Andres Bonifacio Ave., Tibanga, Iligan City 9200, Philippines
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Honda M, Ochiai T, Listiani P, Yamaguchi Y, Ichikawa Y. Low-Temperature Synthesis of Cu-Doped Anatase TiO 2 Nanostructures via Liquid Phase Deposition Method for Enhanced Photocatalysis. MATERIALS (BASEL, SWITZERLAND) 2023; 16:639. [PMID: 36676373 PMCID: PMC9862325 DOI: 10.3390/ma16020639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 12/29/2022] [Accepted: 01/05/2023] [Indexed: 06/17/2023]
Abstract
Titanium dioxide (TiO2) photocatalysis can harness the energy from sunlight, providing a solution to many green- and energy-related problems. In this study, we aimed to produce Cu doped TiO2 (Cu-TiO2) structures at a low temperature (~70 °C) under atmospheric pressure based on liquid phase deposition. The products prepared with Cu nitrate exhibited anatase-phase TiO2 with the presence of Cu, and the particles showed a waxberry-like structure. Changing the Cu nitrate concentration allowed control of the atomic concentration; we confirmed ~1.3 atm.% of Cu ions in the product when we applied 10 mM in the precursor solution. By doping Cu, the light absorption edge shifted to 440 nm (~2.9 eV), and we proved the photocatalytic reaction through action spectral measurement. We observed the decomposition of acetaldehyde into CO2 on Cu-TiO2 photocatalysts, which produced optimized improvements in photocatalytic activity at Cu dopant levels between 0.2 and 0.4 atm.%. This study demonstrates that the liquid phase deposition technique can be used for doping metallic ions into TiO2, which shows promise for preparing novel and unique nanomaterials as visible light photocatalysts.
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Affiliation(s)
- Mitsuhiro Honda
- Graduate School of Engineering, Nagoya Institute of Technology, Nagoya 466-8555, Japan
| | - Tsuyoshi Ochiai
- Materials Analysis Group, Kawasaki Technical Support Department, Kanagawa Institute of Industrial Science and TEChnology (KISTEC), Kawasaki 213-0012, Japan
| | - Popy Listiani
- Graduate School of Engineering, Nagoya Institute of Technology, Nagoya 466-8555, Japan
| | - Yuma Yamaguchi
- Graduate School of Engineering, Nagoya Institute of Technology, Nagoya 466-8555, Japan
| | - Yo Ichikawa
- Graduate School of Engineering, Nagoya Institute of Technology, Nagoya 466-8555, Japan
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Meta-Heuristics Optimization of Mirrors for Gravitational Wave Detectors: Cryogenic Case. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12157680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In this paper, we explore the behavior of several optimization methods for reducing coating Brownian noise in the mirrors of gravitational wave detectors. We will refer to cryogenic operating temperatures, where the low refractive index material has mechanical losses higher than those of the high refractive index material. This situation is the exact opposite of that which occurs at room temperature, which is already widely known. The optimal design of the dielectric mirror (without a priori assumptions on thicknesses) can be obtained through the combined multi-objective optimization of transmittance and thermal noise. In the following, we apply several multi-objective meta-heuristics to compute the Pareto front related to the optimization problem of dielectric mirror thicknesses made of two materials (binary coatings). This approach gives us more certainty about the structure of the final result. We find strong evidence that all meta-heuristics converge to the same solution. The final result can be interpreted with simple physical considerations, providing useful rules to simplify the thicknesses of the optimization algorithm.
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Suwazono Y, Murayoshi T, Nagai H, Sato M. Facile Fabrication of Single-Walled Carbon Nanotube/Anatase Composite Thin Film on Quartz Glass Substrate for Translucent Conductive Photoelectrode. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:3352. [PMID: 34947702 PMCID: PMC8704124 DOI: 10.3390/nano11123352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 12/06/2021] [Accepted: 12/08/2021] [Indexed: 11/26/2022]
Abstract
A single-walled carbon nanotube/anatase (SWCNT/anatase) composite thin film with a transmittance of over 70% in the visible-light region was fabricated on a quartz glass substrate by heat treating a precursor film at 500 °C in air. The precursor film was formed by spin coating a mixed solution of the titania molecular precursor and well-dispersed SWCNTs (0.075 mass%) in ethanol. The anatase crystals and Ti3+ ions in the composite thin films were determined by X-ray diffraction and X-ray photoelectron spectroscopy, respectively. The effect of the heating process on the SWCNTs was analyzed using Raman spectroscopy. The composite film showed an even surface with a scratch resistance of 4H pencil hardness, as observed using field-emission scanning electron microscopy and atomic force microscopy. The electrical resistivity and optical bandgap energy of the composite thin film with a thickness of 100 nm were 6.6 × 10-2 Ω cm and 3.4 eV, respectively, when the SWCNT content in the composite thin film was 2.9 mass%. An anodic photocurrent density of 4.2 μA cm-2 was observed under ultraviolet light irradiation (16 mW cm-2 at 365 nm) onto the composite thin film, thus showing excellent properties as a photoelectrode without conductive substrates.
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Affiliation(s)
- Yutaka Suwazono
- Applied Chemistry and Chemical Engineering Program, Graduate School, Kogakuin University, Tokyo 192-0015, Japan;
| | - Takuro Murayoshi
- Electrical Engineering and Electronics Program, Graduate School, Kogakuin University, Tokyo 192-0015, Japan; (T.M.); (H.N.)
| | - Hiroki Nagai
- Electrical Engineering and Electronics Program, Graduate School, Kogakuin University, Tokyo 192-0015, Japan; (T.M.); (H.N.)
- Department of Applied Physics, School of Advanced Engineering, Kogakuin University, Tokyo 192-0015, Japan
| | - Mitsunobu Sato
- Applied Chemistry and Chemical Engineering Program, Graduate School, Kogakuin University, Tokyo 192-0015, Japan;
- Electrical Engineering and Electronics Program, Graduate School, Kogakuin University, Tokyo 192-0015, Japan; (T.M.); (H.N.)
- Department of Applied Physics, School of Advanced Engineering, Kogakuin University, Tokyo 192-0015, Japan
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Synthesis and Photochemical Properties of Monolithic TiO 2 Nanowires Diode. Molecules 2021; 26:molecules26123636. [PMID: 34203577 PMCID: PMC8232246 DOI: 10.3390/molecules26123636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 06/05/2021] [Accepted: 06/08/2021] [Indexed: 11/16/2022] Open
Abstract
In this paper, the structural and photochemical properties of a monolithic photochemical diode are discussed. The present structure is composed, from the top to the bottom, of a TiO2 nanowire layer, a TiO2 film, a Ti foil, and a porous layer made of Pt nanoparticles. The synthesis of the nanowires was simply carried out by Au-catalysed-assisted process; the effects of the annealing temperature and time were deeply investigated. Morphological and structural characterizations were performed by scanning electron microscopy and Raman spectroscopy. The analyses showed the rutile structure of the TiO2 nanowires. The photocatalytic properties were studied through the degradation of methylene blue (MB) dye under UV light irradiation. The nanowires induced an enhancement of the photo-degradation rate, compared to TiO2 in a bulk form, due to an increase in the surface area. Moreover, the presence of a nano-porous Pt layer deposited on the rear side of the samples provided a further increase in the MB degradation rate, related to the scavenging effect of Pt nanoparticles. The overall increment of the photo-activity, due to the nano-structuration of the TiO2 and to the presence of the Pt layer, resulted a factor 7, compared to the bulk reference. In addition, photovoltage measurements allowed to assess the effects of TiO2 nano-structuration and Pt nanoparticles on the electron accumulation.
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