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Mohapatra B, Sulka GD. Review of Anodic Tantalum Oxide Nanostructures: From Morphological Design to Emerging Applications. ACS APPLIED NANO MATERIALS 2024; 7:13865-13892. [PMID: 38962507 PMCID: PMC11220736 DOI: 10.1021/acsanm.4c02000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Revised: 06/03/2024] [Accepted: 06/07/2024] [Indexed: 07/05/2024]
Abstract
Anodization of transition metals, particularly the valve metals (V, W, Ti, Ta, Hf, Nb, and Zr) and their alloys, has emerged as a powerful tool for controlling the morphology, purity, and thickness of oxide nanostructures. The present review is focused on the advances in the synthesis of micro/nanostructures of anodic tantalum oxides (ATO) in inorganic, organic, and mixed inorganic-organic type electrolytes with critically highlighting anodization parameters, such as applied voltage, current, time, and electrolyte temperature. Particularly, the growth of ATO nanostructures in fluoride containing electrolytes and their applications are briefly covered. The details of the current- or voltage-time transient and its relation to the growth of the anodic oxide films are presented systematically. The main discussion revolves around the incorporation of various electrolyte species into the surface of ATO structures and its effects on their physicochemical properties. The latest progress in understanding the growth mechanism of nanoporous/nanotubular ATO structures is outlined. Additionally, the impact of annealing temperature (ranging from 400-1000 °C) and atmosphere on the crystalline structure, morphology, impurity content, and physical properties of the ATOs is briefly described. The common modification methods, such as decorating with other transition metal/metal oxide, heteroatom doping, or generating defects in the ATO structures, are discussed. Besides, the review also covers the most promising applications of these materials in the fields of capacitors, supercapacitors, memristive devices, corrosion protection, photocatalysis, photoelectrochemical (PEC) water splitting, and biomaterials. Finally, future research directions for designing ATO-based nanomaterials and their utilities are indicated.
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Affiliation(s)
- Biswaranjan
D. Mohapatra
- Department of Physical Chemistry
& Electrochemistry, Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland
| | - Grzegorz Dariusz Sulka
- Department of Physical Chemistry
& Electrochemistry, Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland
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2
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Choi MJ, Hwang YJ, Pyun SB, Kim JH, Kim JY, Hong W, Park JY, Kwak J, Cho EC. Reaction-Based Scalable Inorganic Patterning on Rigid and Soft Substrates for Photovoltaic Roofs with Minimal Optical Loss and Sustainable Sunlight-Driven-Cleaning Windows. ACS APPLIED MATERIALS & INTERFACES 2022; 14:38339-38350. [PMID: 35968862 DOI: 10.1021/acsami.2c09145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Recently developed fabrication methods for inorganic patterns (such as laser printing and optical lithography) can avoid some patterning processes conducted by conventional etching and lithography (such as substrate etching and modulation) and are thereby useful for applications in which the substrates and materials must not be damaged during patterning. Simultaneously, it is also necessary to develop facile and economical methods producing inorganic patterns on various substrates without requiring a special apparatus while attaining the above-mentioned advantages. The present study proposes a reaction-based method for fabricating inorganic patterns by immersing substrates coated with a colloidal nanosheet into an aqueous solution containing inorganic precursors. Silica and TiO2 patterns spontaneously developed during the conversion of each inorganic precursor. These patterns were successful on rigid and flexible substrates. We fabricated these patterns on a wafer-sized silicon and large flexible poly(ethylene terephthalate) film, suggesting the scalability. We fabricated a biomimetic pattern on both sides of a glass window, as a photovoltaic roof, for minimal optical losses to maximally present photovoltaic effects of a solar cell. The TiO2 pattern on glass window exhibits sustainable sunlight-driven-cleaning activity for contaminants. The method could provide a platform for economical high-performance inorganic patterns for energy, environmental, electronics, and other areas.
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Affiliation(s)
- Min Ju Choi
- Department of Chemical Engineering, Hanyang University, Seoul 04763, Republic of Korea
| | - Young Ji Hwang
- Department of Chemical Engineering, Hanyang University, Seoul 04763, Republic of Korea
| | - Seung Beom Pyun
- Department of Chemical Engineering, Hanyang University, Seoul 04763, Republic of Korea
| | - Jeong Han Kim
- Department of Chemical Engineering, Hanyang University, Seoul 04763, Republic of Korea
| | - Jung Yeon Kim
- Department of Chemical Engineering, Hanyang University, Seoul 04763, Republic of Korea
| | - Woongpyo Hong
- Materials Research and Engineering Center, Hyundai Motor Company, 37 Cheoldobangmulgwan-ro, Uiwang-si, Gyeonggi-do 16082, Republic of Korea
| | - Jung-Yeon Park
- Materials Research and Engineering Center, Hyundai Motor Company, 37 Cheoldobangmulgwan-ro, Uiwang-si, Gyeonggi-do 16082, Republic of Korea
| | - Jinwoo Kwak
- Materials Research and Engineering Center, Hyundai Motor Company, 37 Cheoldobangmulgwan-ro, Uiwang-si, Gyeonggi-do 16082, Republic of Korea
| | - Eun Chul Cho
- Department of Chemical Engineering, Hanyang University, Seoul 04763, Republic of Korea
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3
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Kisslinger R, Riddell S, Manuel AP, Alam KM, Kalra AP, Cui K, Shankar K. Nonlithographic Formation of Ta 2O 5 Nanodimple Arrays Using Electrochemical Anodization and Their Use in Plasmonic Photocatalysis for Enhancement of Local Field and Catalytic Activity. ACS APPLIED MATERIALS & INTERFACES 2021; 13:4340-4351. [PMID: 33455157 DOI: 10.1021/acsami.0c18580] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We demonstrate the formation of Ta2O5 nanodimple arrays on technologically relevant non-native substrates through a simple anodization and annealing process. The anodizing voltage determines the pore diameter (25-60 nm), pore depth (2-9 nm), and rate of anodization (1-2 nm/s of Ta consumed). The formation of Ta dimples after delamination of Ta2O5 nanotubes occurs within a range of voltages from 7 to 40 V. The conversion of dimples from Ta into Ta2O5 changes the morphology of the nanodimples but does not impact dimple ordering. Electron energy loss spectroscopy indicated an electronic band gap of 4.5 eV and a bulk plasmon band with a maximum of 21.5 eV. Gold nanoparticles (Au NPs) were coated on Ta2O5 nanodimple arrays by annealing sputtered Au thin films on Ta nanodimple arrays to simultaneously form Au NPs and convert Ta to Ta2O5. Au NPs produced this way showed a localized surface plasmon resonance maximum at 2.08 eV, red-shifted by ∼0.3 eV from the value in air or on SiO2 substrates. Lumerical simulations suggest a partial embedding of the Au NPs to explain this magnitude of the red shift. The resulting plasmonic heterojunctions exhibited a significantly higher ensemble-averaged local field enhancement than Au NPs on quartz substrates and demonstrated much higher catalytic activity for the plasmon-driven photo-oxidation of p-aminothiophenol to p,p'-dimercaptoazobenzene.
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Affiliation(s)
- Ryan Kisslinger
- Department of Electrical and Computer Engineering, University of Alberta, 9211-116 Street, Edmonton, Alberta T6G 1H9, Canada
| | - Saralyn Riddell
- Department of Electrical and Computer Engineering, University of Alberta, 9211-116 Street, Edmonton, Alberta T6G 1H9, Canada
| | - Ajay P Manuel
- Department of Electrical and Computer Engineering, University of Alberta, 9211-116 Street, Edmonton, Alberta T6G 1H9, Canada
| | - Kazi M Alam
- Department of Electrical and Computer Engineering, University of Alberta, 9211-116 Street, Edmonton, Alberta T6G 1H9, Canada
- Nanotechnology Research Centre, National Research Council of Canada, Edmonton, Alberta T6G 1H9, Canada
| | - Aarat P Kalra
- Department of Physics, University of Alberta, 9211-116 Street, Edmonton, Alberta T6G 1H9, Canada
| | - Kai Cui
- Nanotechnology Research Centre, National Research Council of Canada, Edmonton, Alberta T6G 1H9, Canada
| | - Karthik Shankar
- Department of Electrical and Computer Engineering, University of Alberta, 9211-116 Street, Edmonton, Alberta T6G 1H9, Canada
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4
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Horwood CA, Owusu-Ansah E, Shi YJ, Birss VI. Pulsed laser induced dewetting of Au thin films on Ta2O5 substrates. Chem Phys 2021. [DOI: 10.1016/j.chemphys.2020.110926] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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5
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Imbault A, Wang Y, Kruse P, Strelcov E, Comini E, Sberveglieri G, Kolmakov A. Ultrathin Gas Permeable Oxide Membranes for Chemical Sensing: Nanoporous Ta₂O₅ Test Study. MATERIALS 2015; 8:6677-6684. [PMID: 28793592 PMCID: PMC5455363 DOI: 10.3390/ma8105333] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 09/17/2015] [Accepted: 09/21/2015] [Indexed: 11/16/2022]
Abstract
Conductometric gas sensors made of gas permeable metal oxide ultrathin membranes can combine the functions of a selective filter, preconcentrator, and sensing element and thus can be particularly promising for the active sampling of diluted analytes. Here we report a case study of the electron transport and gas sensing properties of such a membrane made of nanoporous Ta2O5. These membranes demonstrated a noticeable chemical sensitivity toward ammonia, ethanol, and acetone at high temperatures above 400 °C. Different from traditional thin films, such gas permeable, ultrathin gas sensing elements can be made suspended enabling advanced architectures of ultrasensitive analytical systems operating at high temperatures and in harsh environments.
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Affiliation(s)
- Alexander Imbault
- Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4M1, Canada.
| | - Yue Wang
- Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4M1, Canada.
| | - Peter Kruse
- Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4M1, Canada.
| | - Evgheni Strelcov
- Oak Ridge National Laboratory, Institute for Functional Imaging of Materials and Center for Nanophase Materials Sciences, Oak Ridge, TN 37831, USA.
| | - Elisabetta Comini
- SENSOR Laboratory, Department of Information Engineering, Brescia University and CNR-INO, Brescia 25133, Italy.
| | - Giorgio Sberveglieri
- SENSOR Laboratory, Department of Information Engineering, Brescia University and CNR-INO, Brescia 25133, Italy.
| | - Andrei Kolmakov
- Department of Physics, Southern Illinois University at Carbondale, Carbondale, IL 62901, USA.
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Buyukaksoy A, Fürstenhaupt T, Birss VI. First-time electrical characterization of nanotubular ZrO2 films for micro-solid oxide fuel cell applications. NANOSCALE 2015; 7:8428-8437. [PMID: 25877824 DOI: 10.1039/c5nr00303b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In this work, anodically grown ZrO2 nanotubes (NTs) are examined for the first time for use in micro solid oxide fuel cell (μ-SOFC) applications. This is due to their high surface area to volume ratio and useful nanoscale morphological features (e.g., 5-100 nm thick NT bases that could serve as the electrolyte layer). To understand their full potential for these applications, the determination of their electrical properties is necessary. Therefore, ZrO2 NTs, in the form of a uniform and crack-free film, were obtained by the two-step anodization of Zr foil in aqueous solutions. The films exhibited excellent adhesion to the Zr substrate, which facilitated impedance spectroscopy analyses, used for the first time to obtain the resistivity of the nanotubular array separately from the contact resistances. This gave a conductivity of the ZrO2 NTs of 1.6 × 10(-6) S cm(-1) at 600 °C in N2, approximately twice that reported for dense ZrO2 films measured at the same temperature in air, and also a very reasonable activation energy of 0.90 eV in the 400-600 °C temperature range.
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Affiliation(s)
- Aligul Buyukaksoy
- Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4.
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7
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El-Sayed HA, Horwood CA, Owusu-Ansah E, Shi YJ, Birss VI. Gold nanoparticle array formation on dimpled Ta templates using pulsed laser-induced thin film dewetting. Phys Chem Chem Phys 2015; 17:11062-9. [PMID: 25824989 DOI: 10.1039/c5cp00924c] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Here we show that pulsed laser-induced dewetting (PLiD) of a thin Au metallic film on a nano-scale ordered dimpled tantalum (DT) surface results in the formation of a high quality Au nanoparticle (NP) array. In contrast to thermal dewetting, PLiD does not result in deformation of the substrate, even when the Au film is heated to above its melting point. PLiD causes local heating of only the metal film and thus thermal oxidation of the Ta substrate can be avoided, also because of the high vacuum (low pO2) environment employed. Therefore, this technique can potentially be used to fabricate NP arrays composed of high melting point metals, such as Pt, not previously possible using conventional thermal annealing methods. We also show that the Au NPs formed by PLiD are more spherical in shape than those formed by thermal dewetting, likely demonstrating a different dewetting mechanism in the two cases. As the metallic NPs formed on DT templates are electrochemically addressable, a longer-term objective of this work is to determine the effect of NP size and shape (formed by laser vs. thermal dewetting) on their electrocatalytic properties.
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Affiliation(s)
- Hany A El-Sayed
- Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4.
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8
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Apolinário A, Sousa CT, Ventura J, Andrade L, Mendes AM, Araújo JP. Tailoring the Ti surface via electropolishing nanopatterning as a route to obtain highly ordered TiO2 nanotubes. NANOTECHNOLOGY 2014; 25:485301. [PMID: 25380180 DOI: 10.1088/0957-4484/25/48/485301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Highly ordered TiO2 nanotubes (NTs) were synthesized by the electrochemical anodization of Ti foils subjected to electropolishing (EP) pre-treatment. We found that the Ti surface roughness plays an important role in the onset of pore nucleation in enhancing the local focusing effect of the electrical field. Additionally, EP induces the formation of dimple structures on the metal surface, which can work as a pre-pattern prior to anodization. These shallow ripples lead to a preferentially ordered pore nucleation, offering an organizational improvement of the anodic oxide NTs. We found that, depending on the EP applied potential, the roughness and the spatial period of the ripple-like structures varies from 8-2 nm and from 122-30 nm, respectively. Such tuning allowed us to focus on the influence of the initial Ti pre-surface topography features on the NTs' length, organization, and hexagonal arrangement quality, as well as diameter and density. Our results show that an EP under 10 V is the most suitable to obtain a small Ti surface roughness, the largest NT length (40% enhancement), and the effective improvement of the ordered hexagonal NTs' arrays over larger areas. Furthermore, the NTs' dimensions (pore diameters and density) were also found to depend on the initial Ti surface topography. The use of optimized EP allows us to obtain highly hexagonal self-ordered samples at a reduced time and cost.
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Affiliation(s)
- A Apolinário
- IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Departamento de Física e Astronomia, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 678, 4169-007 Porto, Portugal
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9
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Electrochemical applications of a Au nanoparticle array fabricated using highly ordered dimpled Ta templates. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2013.07.146] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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10
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McNichols C, Wilkins J, Kubota A, Shiu YT, Aouadi SM, Kohli P. Investigating surface topology and cyclic-RGD peptide functionalization on vascular endothelialization. J Biomed Mater Res A 2013; 102:532-9. [PMID: 23505215 DOI: 10.1002/jbm.a.34700] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2012] [Revised: 01/13/2013] [Accepted: 01/14/2013] [Indexed: 11/09/2022]
Abstract
The advantages of endothelialization of a stent surface in comparison with the bare metal and drug-eluting stents used today include reduced late-stent restenosis and in-stent thrombosis. In this article, we study the effect of surface topology and functionalization of tantalum (Ta) with cyclic-(arginine-glycine-aspartic acid-d-phenylalanine-lysine) (cRGDfK) on the attachment, spreading, and growth of vascular endothelial cells. Self-assembled nanodimpling on Ta surfaces was performed using a one-step electropolishing technique. Next, cRGDfK was covalently bonded onto the surface using silane chemistry. Our results suggest that nanotexturing alone was sufficient to enhance cell spreading, but the combination of a nanodimpled surfaces along with the cRGDfK peptide may produce a better endothelialization coating on the surface in terms of higher cell density, better cell spreading, and more cell-cell interactions, when compared to using cRGDfK peptide functionalization alone or nanotexturing alone. We believe that future research should look into how to implement both modifications (topographic and chemical modifications) to optimize the stent surface for endothelialization.
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Affiliation(s)
- Colton McNichols
- Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale, Illinois
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11
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Sjöström T, Brydone AS, Meek RMD, Dalby MJ, Su B, McNamara LE. Titanium nanofeaturing for enhanced bioactivity of implanted orthopedic and dental devices. Nanomedicine (Lond) 2013; 8:89-104. [PMID: 23256494 DOI: 10.2217/nnm.12.177] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Titanium (Ti) is used as a load-bearing material in the production of orthopedic devices. The clinical efficacy of these implants could be greatly enhanced by the addition of nanofeatures that would improve the bioactivity of the implants, in order to promote in situ osteo-induction and -conduction of the patient's stem and osteoprogenitor cells, and to enhance osseointegration between the implant and the surrounding bone. Nanofeaturing of Ti is also currently being applied as a tool for the biofunctionalization of commercially available dental implants. In this review, we discuss the different nanofabrication strategies that are available to generate nanofeatures in Ti and the cellular response to the resulting nanofeatures. In vitro research, in vivo studies and clinical trials are considered, and we conclude with a perspective about the future potential for use of nanotopographical features in a therapeutic setting.
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Affiliation(s)
- Terje Sjöström
- School of Oral & Dental Science, University of Bristol, Bristol, UK
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12
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Fang C, Bandaru NM, Ellis AV, Voelcker NH. Electrochemical fabrication of nanoporous gold. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm14889g] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Abukhdeir NM, Vlachos DG. Nanoscale surface pattern evolution in heteroepitaxial bimetallic films. ACS NANO 2011; 5:7168-7175. [PMID: 21819095 DOI: 10.1021/nn201979q] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Nanoscale self-assembly dynamics of submonolayer bimetallic films was studied through simulation of a coarse-grained mesoscopic model. Simulations predict a phase transition sequence (hexagonal→stripe→inverse hexagonal) consistent with experimental observations of Pb/Cu(111) heteroepitaxial growth. Post-transition ordering dynamics of hexagonal and inverse hexagonal patterns was simulated and quantified in order to predict pattern quality and evolution mechanisms. Correlation length scaling laws and nanoscale evolution mechanisms were predicted through simulation of experimentally relevant length (≈1 μm(2)) and time scales, with findings supporting evidence of universal pattern behavior with other hexagonal systems. Results provide detailed dynamics and structure of this novel self-assembly process applicable to the design and optimization of functional bimetallic materials, such as bimetallic catalysts.
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14
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Fang C, Ellis AV, Voelcker NH. Electrochemically prepared porous silver and its application in surface-enhanced Raman scattering. J Electroanal Chem (Lausanne) 2011. [DOI: 10.1016/j.jelechem.2011.05.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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15
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Roy P, Berger S, Schmuki P. TiO2 nanotubes: synthesis and applications. Angew Chem Int Ed Engl 2011; 50:2904-39. [PMID: 21394857 DOI: 10.1002/anie.201001374] [Citation(s) in RCA: 1333] [Impact Index Per Article: 102.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Indexed: 11/10/2022]
Abstract
TiO(2) is one of the most studied compounds in materials science. Owing to some outstanding properties it is used for instance in photocatalysis, dye-sensitized solar cells, and biomedical devices. In 1999, first reports showed the feasibility to grow highly ordered arrays of TiO(2) nanotubes by a simple but optimized electrochemical anodization of a titanium metal sheet. This finding stimulated intense research activities that focused on growth, modification, properties, and applications of these one-dimensional nanostructures. This review attempts to cover all these aspects, including underlying principles and key functional features of TiO(2), in a comprehensive way and also indicates potential future directions of the field.
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Affiliation(s)
- Poulomi Roy
- Department of Materials Science, WW4-LKO, University of Erlangen-Nuremberg, Erlangen, Germany
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16
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Gupta G, Bhaskar A, Tripathi B, Pandey P, Boopathi M, Rao PL, Singh B, Vijayaraghavan R. Supersensitive detection of T-2 toxin by the in situ synthesized π-conjugated molecularly imprinted nanopatterns. An in situ investigation by surface plasmon resonance combined with electrochemistry. Biosens Bioelectron 2011; 26:2534-40. [DOI: 10.1016/j.bios.2010.10.050] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Revised: 10/12/2010] [Accepted: 10/28/2010] [Indexed: 12/01/2022]
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17
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El-Sayed HA, Birss VI. Versatile fabrication of self-assembled metallic nanoparticle arrays. ACTA ACUST UNITED AC 2011. [DOI: 10.1039/c1jm12898a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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18
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El-Sayed HA, Birss VI. Controlled growth and monitoring of tantalum oxide nanostructures. NANOSCALE 2010; 2:793-798. [PMID: 20648326 DOI: 10.1039/c0nr00011f] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Nanoporous metal oxide structures produced by the electrochemical anodization of valve metals, such as Zr, Ti, W, Nb, Al, and recently Ta, have attracted increasing interest because of their potential use as catalysts, waveguides, and three-dimensionally arranged Bragg-stack reflectors. Here we demonstrate the formation of either supported nanotubular Ta oxide films or free-standing Ta oxide membranes, produced by controlling the conditions of Ta anodization in organic-free aqueous HF/H(2)SO(4) solutions. The supported oxide nanotubes, which are at least 15 mum in length, are characterized by very good adhesion to the Ta substrate, and extremely smooth and homogeneous walls. It is also reported here, for the first time, that these nanotubular films can be removed as free-standing Ta oxide membranes that are easily transferable to other substrates, making them potentially useful in sensors, optics, and catalysis. We also show that, when the Ta oxide nanotubes detach to form the membranes, they leave behind an ordered array of dimples in the Ta surface, with the dimples having the identical distribution and size as the pores in the previously attached nanotubes. Finally, we demonstrate how the in situ electrochemical response during anodization can be used to determine which of these highly useful Ta surface morphologies (nanotubes vs. dimples) are formed, without the need for post factum microscopic analysis. Knowledge of the meaning of these in situ signals can now serve to accelerate the controlled formation of oxide nanotubes or dimpled surfaces using other combinations of metals and anodization conditions.
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Affiliation(s)
- Hany A El-Sayed
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta, CanadaT2N 1N4
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19
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Liu Y, Hao J, Zhou F. Nanostructure formation via print diffusion etching through block copolymer templates. NANOSCALE 2010; 2:587-593. [PMID: 20644763 DOI: 10.1039/b9nr00350a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The present work demonstrates nanoscale etching of silicon with standard aqueous fluoride etchants running through the hydrophilic domains of a vertically aligned copolymer template. The delivery of etchants was unprecedentedly achieved by an etchant-solution-saturated agarose gel stamp, a technique we call print diffusion etching. Three-dimensional nanoprotrusion features with controllable shapes and sizes (about 20 nm) were formed. To prove that the block copolymers serve to direct the silicon surface morphology by controlling the spatial location of the reaction as well as concentration of reagents, the same etching steps both on silicon and PS-b-PEO (polystyrene-block-polyethyleneoxide) templates were carried out for comparison. The mechanism of the nanoprotrusion formation was elucidated, and the morphology evolution vs. etching time studied.
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Affiliation(s)
- Ying Liu
- State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
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20
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Barton JE, Stender CL, Li P, Odom TW. Structural control of anodized tantalum oxide nanotubes. ACTA ACUST UNITED AC 2009. [DOI: 10.1039/b904964a] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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