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Amani Hamedani H, Stegall T, Yang Y, Wang H, Menon A, Bhalotia A, Karathanasis E, Capadona JR, Hess-Dunning A. Flexible multifunctional titania nanotube array platform for biological interfacing. MRS BULLETIN 2023; 49:299-309. [PMID: 38645611 PMCID: PMC11026245 DOI: 10.1557/s43577-023-00628-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 10/19/2023] [Indexed: 04/23/2024]
Abstract
Abstract The current work presents a novel flexible multifunctional platform for biological interface applications. The use of titania nanotube arrays (TNAs) as a multifunctional material is explored for soft-tissue interface applications. In vitro biocompatibility of TNAs to brain-derived cells was first examined by culturing microglia cells-the resident immune cells of the central nervous system on the surface of TNAs. The release profile of an anti-inflammatory drug, dexamethasone from TNAs-on-polyimide substrates, was then evaluated under different bending modes. Flexible TNAs-on-polyimide sustained a linear release of anti-inflammatory dexamethasone up to ~11 days under different bending conditions. Finally, microfabrication processes for patterning and transferring TNA microsegments were developed to facilitate structural stability during device flexing and to expand the set of compatible polymer substrates. The techniques developed in this study can be applied to integrate TNAs or other similar nanoporous inorganic films onto various polymer substrates. Impact statement Titania nanotube arrays (TNAs) are highly tunable and biocompatible structures that lend themselves to multifunctional implementation in implanted devices. A particularly important aspect of titania nanotubes is their ability to serve as nano-reservoirs for drugs or other therapeutic agents that slowly release after implantation. To date, TNAs have been used to promote integration with rigid, dense tissues for dental and orthopedic applications. This work aims to expand the implant applications that can benefit from TNAs by integrating them onto soft polymer substrates, thereby promoting compatibility with soft tissues. The successful direct growth and integration of TNAs on polymer substrates mark a critical step toward developing mechanically compliant implantable systems with drug delivery from nanostructured inorganic functional materials. Diffusion-driven release kinetics and the high drug-loading efficiency of TNAs offer tremendous potential for sustained drug delivery for scientific investigations, to treat injury and disease, and to promote device integration with biological tissues. This work opens new opportunities for developing novel and more effective implanted devices that can significantly improve patient outcomes and quality of life. Graphical abstract Supplementary information The online version contains supplementary material available at 10.1557/s43577-023-00628-y.
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Affiliation(s)
- Hoda Amani Hamedani
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, USA
- Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, USA
| | - Thomas Stegall
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, USA
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, USA
| | - Yi Yang
- Department of Electrical, Computer, and Systems Engineering, Case Western Reserve University, Cleveland, USA
| | - Haochen Wang
- Department of Electrical, Computer, and Systems Engineering, Case Western Reserve University, Cleveland, USA
| | - Ashwin Menon
- Department of Mechanical Engineering, Case Western Reserve University, Cleveland, USA
| | - Anubhuti Bhalotia
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, USA
| | - Efstathios Karathanasis
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, USA
- Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, Cleveland, USA
| | - Jeffrey R. Capadona
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, USA
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, USA
| | - Allison Hess-Dunning
- Advanced Platform Technology Center, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, USA
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, USA
- Department of Electrical, Computer, and Systems Engineering, Case Western Reserve University, Cleveland, USA
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David TM, Dev PR, Wilson P, Sagayaraj P, Mathews T. A critical review on the variations in anodization parameters toward microstructural formation of TiO
2
nanotubes. ELECTROCHEMICAL SCIENCE ADVANCES 2022. [DOI: 10.1002/elsa.202100083] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- T. Manovah David
- Thin Films and Coatings Section Surface Nanoscience Division Materials Science Group Indira Gandhi Centre for Atomic Research (IGCAR) Kalpakkam India
| | - Priya Ranjan Dev
- Department of Chemistry Madras Christian College (Autonomous) University of Madras Chennai India
| | - P. Wilson
- Department of Chemistry Madras Christian College (Autonomous) University of Madras Chennai India
| | - P. Sagayaraj
- Department of Physics, Loyola College (Autonomous) Chennai India
| | - Tom Mathews
- Thin Films and Coatings Section Surface Nanoscience Division Materials Science Group Indira Gandhi Centre for Atomic Research (IGCAR) Kalpakkam India
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Abstract
The high specific strength, good corrosion resistance, and great biocompatibility make titanium and its alloys the ideal materials for biomedical metallic implants. Ti-6Al-4V alloy is the most employed in practical biomedical applications because of the excellent combination of strength, fracture toughness, and corrosion resistance. However, recent studies have demonstrated some limits in biocompatibility due to the presence of toxic Al and V. Consequently, scientific literature has reported novel biomedical β-Ti alloys containing biocompatible β-stabilizers (such as Mo, Ta, and Zr) studying the possibility to obtain similar performances to the Ti-6Al-4V alloys. The aim of this review is to highlight the corrosion resistance of the passive layers on biomedical Ti-6Al-4V and β-type Ti alloys in the human body environment by reviewing relevant literature research contributions. The discussion is focused on all those factors that influence the performance of the passive layer at the surface of the alloy subjected to electrochemical corrosion, among which the alloy composition, the method selected to grow the oxide coating, and the physicochemical conditions of the body fluid are the most significant.
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Dias-Netipanyj MF, Sopchenski L, Gradowski T, Elifio-Esposito S, Popat KC, Soares P. Crystallinity of TiO 2 nanotubes and its effects on fibroblast viability, adhesion, and proliferation. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2020; 31:94. [PMID: 33128627 DOI: 10.1007/s10856-020-06431-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 09/24/2020] [Indexed: 06/11/2023]
Abstract
Titanium and titanium alloys are widely used as a biomaterial due to their mechanical strength, corrosion resistance, low elastic modulus, and excellent biocompatibility. TiO2 nanotubes have excellent bioactivity, stimulating the adhesion, proliferation of fibroblasts and adipose-derived stem cells, production of alkaline phosphatase by osteoblasts, platelets activation, growth of neural cells and adhesion, spreading, growth, and differentiation of rat bone marrow mesenchymal stem cells. In this study, we investigated the functionality of fibroblast on titania nanotube layers annealed at different temperatures. The titania nanotube layer was fabricated by potentiostatic anodization of titanium, then annealed at 300, 530, and 630 °C for 5 h. The resulting nanotube layer was characterized using SEM (Scanning Electron Microscopy), TF-XRD (Thin-film X-ray diffraction), and contact angle goniometry. Fibroblasts viability was determined by the CellTiter-Blue method and cytotoxicity by Lactate Dehydrogenase test, and the cell morphology was analyzed by scanning electron microscopy. Also, cell adherence, proliferation, and morphology were analyzed by fluorescence microscopy. The results indicate that the modification in nanotube crystallinity may provide a favorable surface fibroblast growth, especially on substrates annealed at 530 and 630 °C, indicating that these properties provide a favorable template for biomedical implants.
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Affiliation(s)
- Marcela Ferreira Dias-Netipanyj
- Graduate Program in Health Science, School of Medicine, Pontifícia Universidade Católica do Paraná, Curitiba, Paraná, Brazil
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA
| | - Luciane Sopchenski
- Department of Mechanical Engineering, Polytechnic School, Pontifícia Universidade Católica do Paraná, Curitiba, Paraná, Brazil
| | - Thatyanne Gradowski
- Graduate Program in Health Science, School of Medicine, Pontifícia Universidade Católica do Paraná, Curitiba, Paraná, Brazil
| | - Selene Elifio-Esposito
- Graduate Program in Health Science, School of Medicine, Pontifícia Universidade Católica do Paraná, Curitiba, Paraná, Brazil
| | - Ketul C Popat
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA
| | - Paulo Soares
- Department of Mechanical Engineering, Polytechnic School, Pontifícia Universidade Católica do Paraná, Curitiba, Paraná, Brazil.
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5
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The In-Depth Studies of Pulsed UV Laser-Modified TiO 2 Nanotubes: The Influence of Geometry, Crystallinity, and Processing Parameters. NANOMATERIALS 2020; 10:nano10030430. [PMID: 32121282 PMCID: PMC7152992 DOI: 10.3390/nano10030430] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 02/18/2020] [Accepted: 02/26/2020] [Indexed: 11/25/2022]
Abstract
The laser processing of the titania nanotubes has been investigated in terms of morphology, structure, and optical properties of the obtained material. The length of the nanotubes and crystallinity, as well as the atmosphere of the laser treatment, were taken into account. The degree of changes of the initial geometry of nanotubes were checked by means of scanning electron microscopy, which visualizes both the surface and the cross-section. The phase conversion from the amorphous to anatase has been achieved for laser-treated amorphous material, whereas modification of calcined one led to distortion within the crystal structure. This result is confirmed both by Raman and grazing incident XRD measurements. The latter studies provided an in-depth analysis of the crystalline arrangement and allowed also for determining the propagation of laser modification. The narrowing of the optical bandgap for laser-treated samples has been observed. Laser treatment of TiO2 nanotubes can lead to the preparation of the material of desired structural and optical parameters. The usage of the motorized table during processing enables induction of changes in the precisely selected area of the sample within a very short time.
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Chemical Gas Sensors Studied at SENSOR Lab, Brescia (Italy): From Conventional to Energy-Efficient and Biocompatible Composite Structures. SENSORS 2020; 20:s20030579. [PMID: 31973066 PMCID: PMC7037366 DOI: 10.3390/s20030579] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 01/17/2020] [Accepted: 01/19/2020] [Indexed: 11/17/2022]
Abstract
In this paper, we present the investigations on metal oxide-based gas sensors considering the works performed at SENSOR lab, University of Brescia (Italy). We reported the developments in synthesis techniques for the preparation of doped and functionalized low-dimensional metal oxide materials. Furthermore, we discussed our achievements in the fabrication of heterostructures with unique functional features. In particular, we focused on the strategies to improve the sensing performance of metal oxides at relatively low operating temperatures. We presented our studies on surface photoactivation of sensing structures considering the application of biocompatible materials in the architecture of the functional devices as well.
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Üzer E, Kumar P, Kisslinger R, Kar P, Thakur UK, Shankar K, Nilges T. Vapor growth of binary and ternary phosphorus-based semiconductors into TiO 2 nanotube arrays and application in visible light driven water splitting. NANOSCALE ADVANCES 2019; 1:2881-2890. [PMID: 36133583 PMCID: PMC9418120 DOI: 10.1039/c9na00084d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 05/17/2019] [Indexed: 06/11/2023]
Abstract
We report successful synthesis of low band gap inorganic polyphosphide and TiO2 heterostructures with the aid of short-way transport reactions. Binary and ternary polyphosphides (NaP7, SnIP, and (CuI)3P12) were successfully reacted and deposited into electrochemically fabricated TiO2 nanotubes. Employing vapor phase reaction deposition, the cavities of 100 μm long TiO2 nanotubes were infiltrated; approximately 50% of the nanotube arrays were estimated to be infiltrated in the case of NaP7. Intensive characterization of the hybrid materials with techniques including SEM, FIB, HR-TEM, Raman spectroscopy, XRD, and XPS proved the successful vapor phase deposition and synthesis of the substances on and inside the nanotubes. The polyphosphide@TiO2 hybrids exhibited superior water splitting performance compared to pristine materials and were found to be more active at higher wavelengths. SnIP@TiO2 emerged to be the most active among the polyphosphide@TiO2 materials. The improved photocatalytic performance might be due to Fermi level re-alignment and a lower charge transfer resistance which facilitated better charge separation from inorganic phosphides to TiO2.
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Affiliation(s)
- Ebru Üzer
- Department of Chemistry, Technical University of Munich Lichtenbergstr. 4 85748 Garching Germany
| | - Pawan Kumar
- Department of Electrical and Computer Engineering 9211-116 Street NW Edmonton Alberta Canada T6G 1H9
| | - Ryan Kisslinger
- Department of Electrical and Computer Engineering 9211-116 Street NW Edmonton Alberta Canada T6G 1H9
| | - Piyush Kar
- Department of Electrical and Computer Engineering 9211-116 Street NW Edmonton Alberta Canada T6G 1H9
| | - Ujwal Kumar Thakur
- Department of Electrical and Computer Engineering 9211-116 Street NW Edmonton Alberta Canada T6G 1H9
| | - Karthik Shankar
- Department of Electrical and Computer Engineering 9211-116 Street NW Edmonton Alberta Canada T6G 1H9
| | - Tom Nilges
- Department of Chemistry, Technical University of Munich Lichtenbergstr. 4 85748 Garching Germany
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8
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Titania Photonic Crystals with Precise Photonic Band Gap Position via Anodizing with Voltage versus Optical Path Length Modulation. NANOMATERIALS 2019; 9:nano9040651. [PMID: 31018593 PMCID: PMC6523195 DOI: 10.3390/nano9040651] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 04/20/2019] [Accepted: 04/20/2019] [Indexed: 12/29/2022]
Abstract
Photonic crystals based on titanium oxide are promising for optoelectronic applications, for example as components of solar cells and photodetectors. These materials attract great research attention because of the high refractive index of TiO2. One of the promising routes to prepare photonic crystals based on titanium oxide is titanium anodizing at periodically changing voltage or current. However, precise control of the photonic band gap position in anodic titania films is a challenge. To solve this problem, systematic data on the effective refractive index of the porous anodic titanium oxide are required. In this research, we determine quantitatively the dependence of the effective refractive index of porous anodic titanium oxide on the anodizing regime and develop a model which allows one to predict and, therefore, control photonic band gap position in the visible spectrum range with an accuracy better than 98.5%. The prospects of anodic titania photonic crystals implementation as refractive index sensors are demonstrated.
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Darabdhara G, Das MR. Dual responsive magnetic Au@Ni nanostructures loaded reduced graphene oxide sheets for colorimetric detection and photocatalytic degradation of toxic phenolic compounds. JOURNAL OF HAZARDOUS MATERIALS 2019; 368:365-377. [PMID: 30690389 DOI: 10.1016/j.jhazmat.2019.01.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Revised: 01/02/2019] [Accepted: 01/06/2019] [Indexed: 06/09/2023]
Abstract
We report the colorimetric detection and photocatalytic degradation of toxic phenolic compounds using Au@Ni loaded reduced graphene oxide (rGO) nanostructures. Core-shell nanoparticles of Au and Ni are successfully designed on rGO with size <8 nm by a solvothermal route which demonstrate excellent enzyme mimic behaviour towards the oxidation of 3,3',5,5' tetramethylbenzidine (TMB), a peroxidase substrate and towards colorimetric detection of phenols with detection limit as low as 1.68 μM, wide detection range of 1-300 μM and admirable selectivity. Additionally, the Au@Ni/rGO nanocomposite exhibits excellent photo responsive behaviour towards degradation of phenol, 2-chlorophenol (2-CP) and 2-nitrophenol (2-NP) under natural sunlight irradiation with more than 87% degradation. The superiority of the bimetallic nanocomposite is established by comparing its activity to its monometallic counterparts. The sustainability of the nanocomposite is assessed through the reusability in the photocatalytic reaction upto six consecutive cycles without significant loss in activity. This is the first study where nanomaterials are used for both detection and degradation of environmental pollutants with positive and encouraging results.
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Affiliation(s)
- Gitashree Darabdhara
- Advanced Materials Group, Materials Sciences and Technology Division, CSIR-North East Institute of Science and Technology, Jorhat, 785006, Assam, India; Academy of Scientific and Innovative Research, CSIR-NEIST Campus, India
| | - Manash R Das
- Advanced Materials Group, Materials Sciences and Technology Division, CSIR-North East Institute of Science and Technology, Jorhat, 785006, Assam, India; Academy of Scientific and Innovative Research, CSIR-NEIST Campus, India.
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10
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Resistance of Superhydrophobic Surface-Functionalized TiO₂ Nanotubes to Corrosion and Intense Cavitation. NANOMATERIALS 2018; 8:nano8100783. [PMID: 30279353 PMCID: PMC6215275 DOI: 10.3390/nano8100783] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Revised: 09/25/2018] [Accepted: 09/27/2018] [Indexed: 12/17/2022]
Abstract
The availability of robust superhydrophobic materials with the ability to withstand harsh environments are in high demand for many applications. In this study, we have presented a simple method to fabricate superhydrophobic materials from TiO2 nanotube arrays (TNTAs) and investigated the resilience of the materials when they are subjected to harsh conditions such as intense cavitation upon ultrasonication, corrosion in saline water, water-jet impact, and abrasion. The TNTAs were prepared by anodization of Ti foil in buffered aqueous electrolyte containing fluoride ions. The hydrophilic TNTAs were functionalized with octadecylphosphonic acid (ODPA) or 1H, 1H′, 2H, 2H′-perfluorodecyl phosphonic acid (PFDPA) to form a self-assembled monolayer on the TNTA surface to produce superhydrophobic ODPA@TNTA or PFDPA@TNTA surfaces. The superhydrophobic ODPA@TNTA and PFDPA@TNTA have contact angles of 156.0° ± 1.5° and 168° ± 1.5°, and contact angle hysteresis of 3.0° and 0.8°, respectively. The superhydrophobic ODPA@TNTA and PFDPA@TNTA were subjected to ultrasonication, corrosion in saline water, and water-jet impact and abrasion, and the resilience of the systems was characterized by electrochemical impedance spectroscopy (EIS), contact angle (CA) measurements, diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS), and field-emission scanning electron microscopy (FESEM). The results presented here show that superhydrophobic ODPA@TNTA and PFDPA@TNTA are robust and resilient under the harsh conditions studied in this work, and indicate the potential of these materials to be deployed in practical applications.
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11
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Zappa D, Galstyan V, Kaur N, Munasinghe Arachchige HMM, Sisman O, Comini E. "Metal oxide -based heterostructures for gas sensors"- A review. Anal Chim Acta 2018; 1039:1-23. [PMID: 30322540 DOI: 10.1016/j.aca.2018.09.020] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 09/10/2018] [Accepted: 09/10/2018] [Indexed: 11/30/2022]
Abstract
This review focuses on the synthesis and chemical sensing characterization of metal oxide heterostructures reported since 2012. Heterostructures exhibit strong interactions between closely packed interfaces, showing superior performances compared to single structures. Surface effects appear thanks to the magnification of nanostructures' surface leading to an enhancement of surface related properties (the base of chemical sensors working mechanism). The combination of different metal oxides to form heterostructures further improves the selectivity and/or other important sensing parameters. A very large number of different morphologies and structures have been proposed, each one exhibiting peculiar sensing properties towards specific chemical compounds. Among the different preparation methodologies, a significant number has been performed by means of hydrothermal method. However, the combination of various fabrication methods seems a very efficient strategy to obtain metal oxide-based heterostructures with different morphologies and dimensions such as core-shell nanostructures, one-dimensional heterostructures, two-dimensional layered heterojunctions, and three-dimensional hierarchical heterostructures. Despite all extraordinary advances in both material science and nanotechnology and the results achieved with heterostructured chemical sensors, there are few points that still deserve further studies and investigations, such as possible diffusion across the junctions, reproducibility of the fabrication process, synergistic or catalytic effects among the materials forming the heterostructures and influence/stability of the contacts. Moreover, perfect control over their growth is mandatory for their application in commercial devices. Only a careful understanding of the growth and the interface properties could fill the existing gap between laboratory studies and real-world exploitation of these heterostructures.
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Affiliation(s)
- Dario Zappa
- SENSOR Laboratory, Dept. of Information Engineering (DII), Università degli Studi di Brescia, Via Valotti 7, 25123, Italy
| | - Vardan Galstyan
- SENSOR Laboratory, Dept. of Information Engineering (DII), Università degli Studi di Brescia, Via Valotti 7, 25123, Italy
| | - Navpreet Kaur
- SENSOR Laboratory, Dept. of Information Engineering (DII), Università degli Studi di Brescia, Via Valotti 7, 25123, Italy
| | | | - Orhan Sisman
- SENSOR Laboratory, Dept. of Information Engineering (DII), Università degli Studi di Brescia, Via Valotti 7, 25123, Italy
| | - Elisabetta Comini
- SENSOR Laboratory, Dept. of Information Engineering (DII), Università degli Studi di Brescia, Via Valotti 7, 25123, Italy.
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Abstract
Metal oxide materials have been applied in different fields due to their excellent functional properties. Metal oxides nanostructuration, preparation with the various morphologies, and their coupling with other structures enhance the unique properties of the materials and open new perspectives for their application in the food industry. Chemical gas sensors that are based on semiconducting metal oxide materials can detect the presence of toxins and volatile organic compounds that are produced in food products due to their spoilage and hazardous processes that may take place during the food aging and transportation. Metal oxide nanomaterials can be used in food processing, packaging, and the preservation industry as well. Moreover, the metal oxide-based nanocomposite structures can provide many advantageous features to the final food packaging material, such as antimicrobial activity, enzyme immobilization, oxygen scavenging, mechanical strength, increasing the stability and the shelf life of food, and securing the food against humidity, temperature, and other physiological factors. In this paper, we review the most recent achievements on the synthesis of metal oxide-based nanostructures and their applications in food quality monitoring and active and intelligent packaging.
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Galstyan V. Porous TiO₂-Based Gas Sensors for Cyber Chemical Systems to Provide Security and Medical Diagnosis. SENSORS 2017; 17:s17122947. [PMID: 29257076 PMCID: PMC5751595 DOI: 10.3390/s17122947] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 12/13/2017] [Accepted: 12/17/2017] [Indexed: 12/31/2022]
Abstract
Gas sensors play an important role in our life, providing control and security of technical processes, environment, transportation and healthcare. Consequently, the development of high performance gas sensor devices is the subject of intense research. TiO2, with its excellent physical and chemical properties, is a very attractive material for the fabrication of chemical sensors. Meanwhile, the emerging technologies are focused on the fabrication of more flexible and smart systems for precise monitoring and diagnosis in real-time. The proposed cyber chemical systems in this paper are based on the integration of cyber elements with the chemical sensor devices. These systems may have a crucial effect on the environmental and industrial safety, control of carriage of dangerous goods and medicine. This review highlights the recent developments on fabrication of porous TiO2-based chemical gas sensors for their application in cyber chemical system showing the convenience and feasibility of such a model to provide the security and to perform the diagnostics. The most of reports have demonstrated that the fabrication of doped, mixed and composite structures based on porous TiO2 may drastically improve its sensing performance. In addition, each component has its unique effect on the sensing properties of material.
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Affiliation(s)
- Vardan Galstyan
- Sensor Lab, Department of Information Engineering, University of Brescia, Via Valotti 9, 25133 Brescia, Italy.
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14
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Investigation of electronic band structure and charge transfer mechanism of oxidized three-dimensional graphene as metal-free anodes material for dye sensitized solar cell application. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.08.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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15
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Dehghani Mahmoudabadi Z, Eslami E. Synthesis of TiO2 nanotubes by atmospheric microplasma electrochemistry: Fabrication, characterization and TiO2 oxide film properties. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2017.05.189] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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16
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Einollahzadeh-Samadi M, Dariani RS, Paul A. Tailoring morphology, structure and photoluminescence properties of anodic TiO2nanotubes. J Appl Crystallogr 2017. [DOI: 10.1107/s1600576717007968] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
TiO2nanotube (TNT) structures were grown perpendicular to fluorine-doped tin-oxide-coated glass substrates by anodic oxidation of titanium films. The morphology, crystal structure and optical properties of the TNTs were shown to be dependent on the thickness of the titanium film, which acts as an electrode in electrochemical anodization. Field emission scanning electron microscopy measurements revealed that an increase in titanium thickness from 1.5 to 2.7 µm caused a considerable increase in both inner diameter and tube length, which in turn increases the porosity and the physical surface of the TNTs per unit area. Grazing-incidence small-angle scattering was used to infer the statistical lateral ordering of the TNTs over macroscopic length scales. X-ray diffraction data show an increase in the texture coefficient for the (004) plane as well as theI004/I101intensity ratio with titanium film thickness. All these factors lead to a significant improvement in the photoluminescence intensity from titania nanotubes, which is about five times more than from titania nanoporous materials under similar circumstances.
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17
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Metal Oxide Gas Sensors, a Survey of Selectivity Issues Addressed at the SENSOR Lab, Brescia (Italy). SENSORS 2017; 17:s17040714. [PMID: 28353673 PMCID: PMC5421674 DOI: 10.3390/s17040714] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 03/18/2017] [Accepted: 03/23/2017] [Indexed: 12/24/2022]
Abstract
This work reports the recent results achieved at the SENSOR Lab, Brescia (Italy) to address the selectivity of metal oxide based gas sensors. In particular, two main strategies are being developed for this purpose: (i) investigating different sensing mechanisms featuring different response spectra that may be potentially integrated in a single device; (ii) exploiting the electronic nose (EN) approach. The former has been addressed only recently and activities are mainly focused on determining the most suitable configuration and measurements to exploit the novel mechanism. Devices suitable to exploit optical (photoluminescence), magnetic (magneto-optical Kerr effect) and surface ionization in addition to the traditional chemiresistor device are here discussed together with the sensing performance measured so far. The electronic nose is a much more consolidated technology, and results are shown concerning its suitability to respond to industrial and societal needs in the fields of food quality control and detection of microbial activity in human sweat.
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Khudhair D, Bhatti A, Li Y, Hamedani HA, Garmestani H, Hodgson P, Nahavandi S. Anodization parameters influencing the morphology and electrical properties of TiO2 nanotubes for living cell interfacing and investigations. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2015; 59:1125-1142. [PMID: 26652471 DOI: 10.1016/j.msec.2015.10.042] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 07/16/2015] [Accepted: 10/13/2015] [Indexed: 01/25/2023]
Abstract
Nanotube structures have attracted tremendous attention in recent years in many applications. Among such nanotube structures, titania nanotubes (TiO2) have received paramount attention in the medical domain due to their unique properties, represented by high corrosion resistance, good mechanical properties, high specific surface area, as well as great cell proliferation, adhesion and mineralization. Although lot of research has been reported in developing optimized titanium nanotube structures for different medical applications, however there is a lack of unified literature source that could provide information about the key parameters and experimental conditions required to develop such optimized structure. This paper addresses this gap, by focussing on the fabrication of TiO2 nanotubes through anodization process on both pure titanium and titanium alloys substrates to exploit the biocompatibility and electrical conductivity aspects, critical factors for many medical applications from implants to in-vivo and in-vitro living cell studies. It is shown that the morphology of TiO2 directly impacts the biocompatibility aspects of the titanium in terms of cell proliferation, adhesion and mineralization. Similarly, TiO2 nanotube wall thickness of 30-40nm has shown to exhibit improved electrical behaviour, a critical factor in brain mapping and behaviour investigations if such nanotubes are employed as micro-nano-electrodes.
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Affiliation(s)
- D Khudhair
- Deakin University, Waurn Ponds Campus, Vic 3216, Australia
| | - A Bhatti
- Deakin University, Waurn Ponds Campus, Vic 3216, Australia.
| | - Y Li
- RMIT University, Bundoora, Victoria 3083, Australia
| | | | | | - P Hodgson
- Deakin University, Waurn Ponds Campus, Vic 3216, Australia
| | - S Nahavandi
- Deakin University, Waurn Ponds Campus, Vic 3216, Australia
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19
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Concina I, Vomiero A. Metal oxide semiconductors for dye- and quantum-dot-sensitized solar cells. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2015; 11:1744-1774. [PMID: 25523717 DOI: 10.1002/smll.201402334] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 10/04/2014] [Indexed: 06/04/2023]
Abstract
This Review provides a brief summary of the most recent research developments in the synthesis and application of nanostructured metal oxide semiconductors for dye sensitized and quantum dot sensitized solar cells. In these devices, the wide bandgap semiconducting oxide acts as the photoanode, which provides the scaffold for light harvesters (either dye molecules or quantum dots) and electron collection. For this reason, proper tailoring of the optical and electronic properties of the photoanode can significantly boost the functionalities of the operating device. Optimization of the functional properties relies with modulation of the shape and structure of the photoanode, as well as on application of different materials (TiO2, ZnO, SnO2) and/or composite systems, which allow fine tuning of electronic band structure. This aspect is critical because it determines exciton and charge dynamics in the photoelectrochemical system and is strictly connected to the photoconversion efficiency of the solar cell. The different strategies for increasing light harvesting and charge collection, inhibiting charge losses due to recombination phenomena, are reviewed thoroughly, highlighting the benefits of proper photoanode preparation, and its crucial role in the development of high efficiency dye sensitized and quantum dot sensitized solar cells.
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Affiliation(s)
- Isabella Concina
- CNR-INO SENSOR Lab, Via Branze 45, 25123, Brescia, Italy; University of Brescia, Via Valotti 9, 25133, Brescia, Italy
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20
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Joseph S, Sagayaraj P. A cost effective approach for developing substrate stable TiO2 nanotube arrays with tuned morphology: a comprehensive study on the role of H2O2 and anodization potential. NEW J CHEM 2015. [DOI: 10.1039/c5nj00565e] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The figure shows the FESEM image of the self-organized, highly ordered TiO2 nanotube arrays formed with an anodization potential of 60 V employing 3 vol% of H2O2 in an ethylene glycol electrolyte. The sample exhibited a maximum porosity of 88%.
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Affiliation(s)
- Shibu Joseph
- Department of Physics
- Loyola College (Autonomous)
- Chennai-600 034
- India
| | - Pappu Sagayaraj
- Department of Physics
- Loyola College (Autonomous)
- Chennai-600 034
- India
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21
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Damodaran VB, Bhatnagar D, Leszczak V, Popat KC. Titania nanostructures: a biomedical perspective. RSC Adv 2015. [DOI: 10.1039/c5ra04271b] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
A systematic and comprehensive summary of various TNS-based biomedical research with a special emphasis on drug-delivery, tissue engineering, biosensor, and anti-bacterial applications.
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Affiliation(s)
- Vinod B. Damodaran
- New Jersey Center for Biomaterials and Rutgers – The State University of New Jersey
- Piscataway
- USA
| | - Divya Bhatnagar
- New Jersey Center for Biomaterials and Rutgers – The State University of New Jersey
- Piscataway
- USA
| | - Victoria Leszczak
- Department of Mechanical Engineering and School of Biomedical Engineering
- Colorado State University
- Fort Collins
- USA
| | - Ketul C. Popat
- Department of Mechanical Engineering and School of Biomedical Engineering
- Colorado State University
- Fort Collins
- USA
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22
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Fischer K, Kühnert M, Gläser R, Schulze A. Photocatalytic degradation and toxicity evaluation of diclofenac by nanotubular titanium dioxide–PES membrane in a static and continuous setup. RSC Adv 2015. [DOI: 10.1039/c4ra16219f] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Diclofenac is a commonly used anti-inflammatory drug, which has been found in surface waters. TiO2 nanotubes with a polymer microfiltration membrane showed high photocatalytic degradation of diclofenac combined with an excellent membrane performance and long term stability.
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Affiliation(s)
- K. Fischer
- Leibniz Institute of Surface Modification
- Leipzig
- Germany
| | - M. Kühnert
- Leibniz Institute of Surface Modification
- Leipzig
- Germany
| | - R. Gläser
- Leipzig University
- Institute of Chemical Technology
- Leipzig
- Germany
| | - A. Schulze
- Leibniz Institute of Surface Modification
- Leipzig
- Germany
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23
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Bhowmik B, Bhattacharyya P. Highly stable low temperature alcohol sensor based on hydrothermally grown tetragonal titania nanorods. RSC Adv 2015. [DOI: 10.1039/c5ra14518j] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Highly stable, low temperature (27–175 °C) alcohol (ethanol, methanol and 2-propanol) sensing performance of a hydrothermally grown tetragonal TiO2 nanorod array, targeting the detection level of 1–100 ppm, is reported in this paper.
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Affiliation(s)
- B. Bhowmik
- Nano Thin Film and Solid State Gas Sensor Devices Laboratory
- Department of Electronics and Telecommunication Engineering
- Indian Institute of Engineering Science and Technology
- Howrah
- India
| | - P. Bhattacharyya
- Nano Thin Film and Solid State Gas Sensor Devices Laboratory
- Department of Electronics and Telecommunication Engineering
- Indian Institute of Engineering Science and Technology
- Howrah
- India
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24
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Castro AGB, Bastos AC, Galstyan V, Faglia G, Sberveglieri G, Miranda Salvado IM. Synthesis and electrochemical study of a hybrid structure based on PDMS-TEOS and titania nanotubes for biomedical applications. NANOTECHNOLOGY 2014; 25:365701. [PMID: 25141030 DOI: 10.1088/0957-4484/25/36/365701] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Metallic implants and devices are widely used in the orthopedic and orthodontic clinical areas. However, several problems regarding their adhesion with the living tissues and inflammatory responses due to the release of metallic ions to the medium have been reported. The modification of the metallic surfaces and the use of biocompatible protective coatings are two approaches to solve such issues. In this study, in order to improve the adhesion properties and to increase the corrosion resistance of metallic Ti substrates we have obtained a hybrid structure based on TiO₂ nanotubular arrays and PDMS-TEOS films. TiO₂ nanotubes have been prepared with two different diameters by means of electrochemical anodization. PDMS-TEOS films have been prepared by the sol-gel method. The morphological and the elemental analysis of the structures have been investigated by scanning electron microscopy and energy dispersive spectroscopy (EDS). Electrochemical impedance spectroscopy (EIS) and polarization curves have been performed during immersion of the samples in Kokubo's simulated body fluid (SBF) at 37 °C to study the effect of structure layers and tube diameter on the protective properties. The obtained results show that the modification of the surface structure of TiO₂ and the application of PDMS-TEOS film is a promising strategy for the development of implant materials.
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Lee K, Mazare A, Schmuki P. One-dimensional titanium dioxide nanomaterials: nanotubes. Chem Rev 2014; 114:9385-454. [PMID: 25121734 DOI: 10.1021/cr500061m] [Citation(s) in RCA: 506] [Impact Index Per Article: 50.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Kiyoung Lee
- Department of Materials Science WW4-LKO, University of Erlangen-Nuremberg , Martensstrasse 7, 91058 Erlangen, Germany
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26
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Selopal GS, Memarian N, Milan R, Concina I, Sberveglieri G, Vomiero A. Effect of blocking layer to boost photoconversion efficiency in ZnO dye-sensitized solar cells. ACS APPLIED MATERIALS & INTERFACES 2014; 6:11236-11244. [PMID: 24940846 DOI: 10.1021/am501360a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The effect of a ZnO compact blocking layer (BL) in dye-sensitized solar cells (DSSCs) based on ZnO photoanodes is investigated. BL is generated through spray deposition onto fluorine-doped tin oxide (FTO) conducting glass before the deposition of a ZnO active layer. The functional properties of dye-sensitized solar cells (DSSCs) are then investigated as a function of the thickness of the BL for two different kinds of ZnO active layer, i.e., hierarchically self-assembled nanoparticles and microcubes composed of closely packed ZnO sheets. Presence of BL leads to the improvement of photoconversion efficiency (PCE), by physically insulating the electrolyte and the FTO. This effect increases at increasing BL thickness up to around 800 nm, while thicker BL results in reduced cell performance. Remarkable increase in Jsc is recorded, which doubles as compared to cells without blocking layer, leading to PCE as high as 5.6% in the best cell under one sun irradiation (AM 1.5 G, 100 mW cm(-2)). Electrochemical impedance spectroscopy (EIS) elucidates the mechanism boosting the functional features of the cells with BL, which relies with enhanced chemical capacitance together with an almost unchanged recombination resistance, which are reflected in an increased electron lifetime. The results foresee a straightforward way to significantly improve the performance of ZnO-based DSSCs.
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Affiliation(s)
- Gurpreet Singh Selopal
- SENSOR Lab, Department of Information Engineering, University of Brescia , Via Valotti 9, 25133 Brescia, Italy
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27
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Shao D, Li X, Xu H, Yan W. An improved stable Ti/Sb–SnO2 electrode with high performance in electrochemical oxidation processes. RSC Adv 2014. [DOI: 10.1039/c4ra01990c] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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28
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Galstyan V, Comini E, Faglia G, Sberveglieri G. Synthesis of self-ordered and well-aligned Nb2O5 nanotubes. CrystEngComm 2014. [DOI: 10.1039/c4ce01540a] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In the present work we demonstrate the fabrication of self-assembled and highly aligned Nb2O5 nanotubes by means of electrochemical anodization of metallic Nb at room temperature.
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Affiliation(s)
- Vardan Galstyan
- Sensor Lab
- Department of Information Engineering
- University of Brescia and CNR INO
- 25133 Brescia, Italy
| | - Elisabetta Comini
- Sensor Lab
- Department of Information Engineering
- University of Brescia and CNR INO
- 25133 Brescia, Italy
| | - Guido Faglia
- Sensor Lab
- Department of Information Engineering
- University of Brescia and CNR INO
- 25133 Brescia, Italy
| | - Giorgio Sberveglieri
- Sensor Lab
- Department of Information Engineering
- University of Brescia and CNR INO
- 25133 Brescia, Italy
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29
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Liang J, Zhang G, Sun W. Post-treatment on dye-sensitized solar cells with TiCl4 and Nb2O5. RSC Adv 2014. [DOI: 10.1039/c3ra46188b] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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30
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Vaenas N, Stergiopoulos T, Kontos AG, Likodimos V, Falaras P. Influence of controlled-charge anodization processes on the morphology of TiO2 nanotubes and their efficiency in dye-sensitized solar cells. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2013.09.118] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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31
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Galstyan V, Comini E, Faglia G, Sberveglieri G. TiO2 nanotubes: recent advances in synthesis and gas sensing properties. SENSORS 2013; 13:14813-38. [PMID: 24184919 PMCID: PMC3871103 DOI: 10.3390/s131114813] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 10/22/2013] [Accepted: 10/25/2013] [Indexed: 11/16/2022]
Abstract
Synthesis--particularly by electrochemical anodization-, growth mechanism and chemical sensing properties of pure, doped and mixed titania tubular arrays are reviewed. The first part deals on how anodization parameters affect the size, shape and morphology of titania nanotubes. In the second part fabrication of sensing devices based on titania nanotubes is presented, together with their most notable gas sensing performances. Doping largely improves conductivity and enhances gas sensing performances of TiO2 nanotubes.
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Affiliation(s)
- Vardan Galstyan
- Authors to whom correspondence should be addressed; E-Mails: (V.G.); (E.C.)
| | - Elisabetta Comini
- Authors to whom correspondence should be addressed; E-Mails: (V.G.); (E.C.)
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32
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Kuo YY, Chien CH. Sinter-free transferring of anodized TiO2 nanotube-array onto a flexible and transparent sheet for dye-sensitized solar cells. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2013.01.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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33
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Hyam RS, Choi D. Effects of titanium foil thickness on TiO2 nanostructures synthesized by anodization. RSC Adv 2013. [DOI: 10.1039/c3ra40581h] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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34
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Controlling Morphological Parameters of Anodized Titania Nanotubes for Optimized Solar Energy Applications. MATERIALS 2012. [PMCID: PMC5449041 DOI: 10.3390/ma5101890] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Anodized TiO2 nanotubes have received much attention for their use in solar energy applications including water oxidation cells and hybrid solar cells [dye-sensitized solar cells (DSSCs) and bulk heterojuntion solar cells (BHJs)]. High surface area allows for increased dye-adsorption and photon absorption. Titania nanotubes grown by anodization of titanium in fluoride-containing electrolytes are aligned perpendicular to the substrate surface, reducing the electron diffusion path to the external circuit in solar cells. The nanotube morphology can be optimized for the various applications by adjusting the anodization parameters but the optimum crystallinity of the nanotube arrays remains to be realized. In addition to morphology and crystallinity, the method of device fabrication significantly affects photon and electron dynamics and its energy conversion efficiency. This paper provides the state-of-the-art knowledge to achieve experimental tailoring of morphological parameters including nanotube diameter, length, wall thickness, array surface smoothness, and annealing of nanotube arrays.
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Galstyan V, Comini E, Faglia G, Vomiero A, Borgese L, Bontempi E, Sberveglieri G. Fabrication and investigation of gas sensing properties of Nb-doped TiO(2) nanotubular arrays. NANOTECHNOLOGY 2012; 23:235706. [PMID: 22595952 DOI: 10.1088/0957-4484/23/23/235706] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Synthesis of Nb-containing titania nanotubular arrays at room temperature by electrochemical anodization is reported. Crystallization of pure and Nb-doped TiO(2) nanotubes was carried out by post-growth annealing at 400°C. The morphology of the tubes obtained was characterized by scanning electron microscopy (SEM). Crystal structure and composition of tubes were investigated by glancing incidence x-ray diffraction (GIXRD) and total reflection x-ray fluorescence (TXRF). For the first time gas sensing characteristics of Nb-doped TiO(2) nanotubes were investigated and compared to those of undoped nanotubes. The functional properties of nanotubular arrays towards CO, H(2), NO(2), ethanol and acetone were tested in a wide range of operating temperature. The introduction of Nb largely improves conductivity and enhances gas sensing performances of TiO(2) nanotubes.
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Affiliation(s)
- Vardan Galstyan
- SENSOR Lab, Department of Chemistry and Physics, University of Brescia and CNR-IDASC, via Valotti 9, Brescia, Italy.
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