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Heikkinen N, Lehtonen J, Puurunen RL. An atomic layer deposition diffusion-reaction model for porous media with different particle geometries. Phys Chem Chem Phys 2024; 26:7580-7591. [PMID: 38362743 DOI: 10.1039/d3cp05639b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
This work presents a diffusion-reaction model for atomic layer deposition (ALD), which has been adapted to describe radial direction reactant transport and adsorption kinetics in a porous particle. Specifically, we present the effect of three particle geometries: spherical, cylindrical and a slab in the diffusion-reaction model. The reactant diffusion propagates as a unidimensional front inside the slab particle, whereas with cylinder and spherical particles, the reactant diffusion approaches the particle centre from two and three dimensions, respectively. Due to additional reactant propagation dimensions, cylindrical and spherical particles require less exposure for full particle penetration. In addition to the particle geometry effect, a sensitivity analysis was used to compare the impact of the particles' physical properties on the achieved penetration depth. The analysis evaluates properties, such as the combined porosity and tortuosity factor, mean pore diameter, specific surface area, pore volume, and particle radius. Furthermore, we address the impact of the reactant molar mass, growth-per-cycle (GPC), sticking probability, reactant exposure and deposition temperature on the simulated diffusion and surface coverage profiles. The diffusion-reaction model presented in this work is relevant for the design and optimization of ALD processes in porous media with different particle geometries.
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Affiliation(s)
- Niko Heikkinen
- VTT Technical Research Centre of Finland, P.O. Box 1000, FIN-02044 VTT, Espoo, Finland.
| | - Juha Lehtonen
- VTT Technical Research Centre of Finland, P.O. Box 1000, FIN-02044 VTT, Espoo, Finland.
| | - Riikka L Puurunen
- Department of Chemical and Metallurgical Engineering, Aalto University School of Chemical Engineering, Kemistintie 1, Espoo, Finland.
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2
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Jessl S, Engelke S, Copic D, Baumberg JJ, De Volder M. Anisotropic Carbon Nanotube Structures with High Aspect Ratio Nanopores for Li-Ion Battery Anodes. ACS APPLIED NANO MATERIALS 2021; 4:6299-6305. [PMID: 34240009 PMCID: PMC8240089 DOI: 10.1021/acsanm.1c01157] [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: 05/04/2021] [Accepted: 06/09/2021] [Indexed: 06/13/2023]
Abstract
Technological advances in membrane technology, catalysis, and electrochemical energy storage require the fabrication of controlled pore structures at ever smaller length scales. It is therefore important to develop processes allowing for the fabrication of materials with controlled submicron porous structures. We propose a combination of colloidal lithography and chemical vapor deposition of carbon nanotubes to create continuous straight pores with diameters down to 100 nm in structures with thicknesses of more than 300 μm. These structures offer unique features, including continuous and parallel pores with aspect ratios in excess of 3000, a low pore tortuosity, good electrical conductivity, and electrochemical stability. We demonstrate that these structures can be used in Li-ion batteries by coating the carbon nanotubes with Si as an active anode material.
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Affiliation(s)
- Sarah Jessl
- Department
of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom
| | - Simon Engelke
- Department
of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom
- Cambridge
Graphene Centre, University of Cambridge, Cambridge CB3 0FA, United Kingdom
| | - Davor Copic
- Department
of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom
| | - Jeremy J. Baumberg
- NanoPhotonics
Centre, Cavendish Laboratory, University
of Cambridge, Cambridge CB3 0HE, United Kingdom
| | - Michael De Volder
- Department
of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom
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3
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Szmyt W, Guerra-Nuñez C, Dransfeld C, Utke I. Solving the inverse Knudsen problem: Gas diffusion in random fibrous media. J Memb Sci 2021. [DOI: 10.1016/j.memsci.2020.118728] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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4
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Mirza Gheitaghy A, Poelma RH, Sacco L, Vollebregt S, Zhang GQ. Vertically-Aligned Multi-Walled Carbon Nano Tube Pillars with Various Diameters under Compression: Pristine and NbTiN Coated. NANOMATERIALS 2020; 10:nano10061189. [PMID: 32570835 PMCID: PMC7353429 DOI: 10.3390/nano10061189] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Revised: 06/16/2020] [Accepted: 06/17/2020] [Indexed: 10/25/2022]
Abstract
In this paper, the compressive stress of pristine and coated vertically-aligned (VA) multi-walled (MW) carbon nanotube (CNT) pillars were investigated using flat-punch nano-indentation. VA-MWCNT pillars of various diameters (30-150 µm) grown by low-pressure chemical vapor deposition on silicon wafer. A conformal brittle coating of niobium-titanium-nitride with high superconductivity temperature was deposited on the VA-MWCNT pillars using atomic layer deposition. The coating together with the pillars could form a superconductive vertical interconnect. The indentation tests showed foam-like behavior of pristine CNTs and ceramic-like fracture of conformal coated CNTs. The compressive strength and the elastic modulus for pristine CNTs could be divided into three regimes of linear elastic, oscillatory plateau, and exponential densification. The elastic modulus of pristine CNTs increased for a smaller pillar diameter. The response of the coated VA-MWCNTs depended on the diffusion depth of the coating in the pillar and their elastic modulus increased with pillar diameter due to the higher sidewall area. Tuning the material properties by conformal coating on various diameter pillars enhanced the mechanical performance and the vertical interconnect access (via) reliability. The results could be useful for quantum computing applications that require high-density superconducting vertical interconnects and reliable operation at reduced temperatures.
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5
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Atomic Layer Deposition of Inorganic Films for the Synthesis of Vertically Aligned Carbon Nanotube Arrays and Their Hybrids. COATINGS 2019. [DOI: 10.3390/coatings9120806] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Vertically aligned carbon nanotube arrays (VACNTs) have many excellent properties and show great potential for various applications. Recently, there has been a desire to grow VACNTs on nonplanar surfaces and synthesize core-sheath-structured VACNT–inorganic hybrids. To achieve this aim, atomic layer deposition (ALD) has been extensively applied, especially due to its atomic-scale thickness controllability and excellent conformality of films on three-dimensional (3D) structures with high aspect ratios. In this paper, the ALD of catalyst thin films for the growth of VACNTs, such as Co3O4, Al2O3, and Fe2O3, was first mentioned. After that, the ALD of thin films for the synthesis of VACNT–inorganic hybrids was also discussed. To highlight the importance of these hybrids, their potential applications in supercapacitors, solar cells, fuel cells, and sensors have also been reviewed.
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6
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Silvestri C, Riccio M, Poelma RH, Jovic A, Morana B, Vollebregt S, Irace A, Zhang GQ, Sarro PM. Effects of Conformal Nanoscale Coatings on Thermal Performance of Vertically Aligned Carbon Nanotubes. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1800614. [PMID: 29665299 DOI: 10.1002/smll.201800614] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 03/05/2018] [Indexed: 06/08/2023]
Abstract
The high aspect ratio and the porous nature of spatially oriented forest-like carbon nanotube (CNT) structures represent a unique opportunity to engineer a novel class of nanoscale assemblies. By combining CNTs and conformal coatings, a 3D lightweight scaffold with tailored behavior can be achieved. The effect of nanoscale coatings, aluminum oxide (Al2 O3 ) and nonstoichiometric amorphous silicon carbide (a-SiC), on the thermal transport efficiency of high aspect ratio vertically aligned CNTs, is reported herein. The thermal performance of the CNT-based nanostructure strongly depends on the achieved porosity, the coating material and its infiltration within the nanotube network. An unprecedented enhancement in terms of effective thermal conductivity in a-SiC coated CNTs has been obtained: 181% compared to the as-grown CNTs and Al2 O3 coated CNTs. Furthermore, the integration of coated high aspect ratio CNTs in an epoxy molding compound demonstrates that, next to the required thermal conductivity, the mechanical compliance for thermal interface applications can also be achieved through coating infiltration into foam-like CNT forests.
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Affiliation(s)
- Cinzia Silvestri
- Department of Microelectronics, Delft University of Technology, Feldmannweg 17, 2628CT, Delft, The Netherlands
| | - Michele Riccio
- Department of Electrical Engineering and Information Technologies, University of Naples Federico II, Via Claudio 21, 80125, Naples, Italy
| | - René H Poelma
- Department of Microelectronics, Delft University of Technology, Feldmannweg 17, 2628CT, Delft, The Netherlands
| | - Aleksandar Jovic
- Department of Microelectronics, Delft University of Technology, Feldmannweg 17, 2628CT, Delft, The Netherlands
| | - Bruno Morana
- Department of Microelectronics, Delft University of Technology, Feldmannweg 17, 2628CT, Delft, The Netherlands
| | - Sten Vollebregt
- Department of Microelectronics, Delft University of Technology, Feldmannweg 17, 2628CT, Delft, The Netherlands
| | - Andrea Irace
- Department of Electrical Engineering and Information Technologies, University of Naples Federico II, Via Claudio 21, 80125, Naples, Italy
| | - Guo Qi Zhang
- Department of Microelectronics, Delft University of Technology, Feldmannweg 17, 2628CT, Delft, The Netherlands
| | - Pasqualina M Sarro
- Department of Microelectronics, Delft University of Technology, Feldmannweg 17, 2628CT, Delft, The Netherlands
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7
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Borzenkov M, Chirico G, Collini M, Pallavicini P. Gold Nanoparticles for Tissue Engineering. ENVIRONMENTAL NANOTECHNOLOGY 2018. [DOI: 10.1007/978-3-319-76090-2_10] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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8
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Szmyt W, Guerra C, Utke I. Diffusion of dilute gas in arrays of randomly distributed, vertically aligned, high-aspect-ratio cylinders. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2017; 8:64-73. [PMID: 28144565 PMCID: PMC5238662 DOI: 10.3762/bjnano.8.7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 12/13/2016] [Indexed: 06/06/2023]
Abstract
In this work we modelled the diffusive transport of a dilute gas along arrays of randomly distributed, vertically aligned nanocylinders (nanotubes or nanowires) as opposed to gas diffusion in long pores, which is described by the well-known Knudsen theory. Analytical expressions for (i) the gas diffusion coefficient inside such arrays, (ii) the time between collisions of molecules with the nanocylinder walls (mean time of flight), (iii) the surface impingement rate, and (iv) the Knudsen number of such a system were rigidly derived based on a random-walk model of a molecule that undergoes memoryless, diffusive reflections from nanocylinder walls assuming the molecular regime of gas transport. It can be specifically shown that the gas diffusion coefficient inside such arrays is inversely proportional to the areal density of cylinders and their mean diameter. An example calculation of a diffusion coefficient is delivered for a system of titanium isopropoxide molecules diffusing between vertically aligned carbon nanotubes. Our findings are important for the correct modelling and optimisation of gas-based deposition techniques, such as atomic layer deposition or chemical vapour deposition, frequently used for surface functionalisation of high-aspect-ratio nanocylinder arrays in solar cells and energy storage applications. Furthermore, gas sensing devices with high-aspect-ratio nanocylinder arrays and the growth of vertically aligned carbon nanotubes need the fundamental understanding and precise modelling of gas transport to optimise such processes.
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Affiliation(s)
- Wojciech Szmyt
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Mechanics of Materials and Nanostructures, Feuerwerkerstrasse 39, 3602 Thun, Switzerland
- AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. A. Mickiewicza 30, 30-059 Krakow, Poland
- now working at: FHNW University of Applied Sciences and Arts Northwestern Switzerland, Institute of Polymer Engineering, Klosterzelgstrasse 2, 5210 Windisch, Switzerland
| | - Carlos Guerra
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Mechanics of Materials and Nanostructures, Feuerwerkerstrasse 39, 3602 Thun, Switzerland
| | - Ivo Utke
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Mechanics of Materials and Nanostructures, Feuerwerkerstrasse 39, 3602 Thun, Switzerland
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9
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Zhao H, Jacob C, Stone HA, Hart AJ. Liquid Imbibition in Ceramic-Coated Carbon Nanotube Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:12686-12692. [PMID: 27934531 DOI: 10.1021/acs.langmuir.6b03661] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Understanding of the liquid imbibition dynamics in nanoporous materials is important to advances in chemical separations, phase change heat transfer, electrochemical energy storage, and diagnostic assays. We study the liquid imbibition behavior in films of ceramic-coated vertically aligned carbon nanotubes (CNTs). The nanoscale porosity of the films is tuned by conformal ceramic coating via atomic layer deposition (ALD), enabling stable liquid imbibition and precise measurement of the imbibition dynamics without capillary densification of the CNTs. We show that the imbibition rate decreases as the ceramic coating thickness increases, which effectively changes the CNT-CNT spacing and therefore decreases the permeability. We derive a model, based on Darcy's law, that incorporates an expression for the permeability of nanoscale post arrays, and we show that the model fits the experimental results with high accuracy. The tailorable porosity, along with controllable surface wettability and mechanical stability of coated CNTs, suggest their suitability for application-guided engineering, and for further investigation of imbibition behavior at finer length scales.
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Affiliation(s)
- Hangbo Zhao
- Department of Mechanical Engineering and Laboratory for Manufacturing and Productivity, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Christine Jacob
- Department of Mechanical Engineering and Laboratory for Manufacturing and Productivity, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Howard A Stone
- Department of Mechanical and Aerospace Engineering, Princeton University , Princeton, New Jersey 08544, United States
| | - A John Hart
- Department of Mechanical Engineering and Laboratory for Manufacturing and Productivity, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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10
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Silva RM, Ferro MC, Araujo JR, Achete CA, Clavel G, Silva RF, Pinna N. Nucleation, Growth Mechanism, and Controlled Coating of ZnO ALD onto Vertically Aligned N-Doped CNTs. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:7038-7044. [PMID: 27333190 DOI: 10.1021/acs.langmuir.6b00869] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Zinc oxide thin films were deposited on vertically aligned nitrogen-doped carbon nanotubes (N-CNTs) by atomic layer deposition (ALD) from diethylzinc and water. The study demonstrates that doping CNTs with nitrogen is an effective approach for the "activation" of the CNTs surface for the ALD of metal oxides. Conformal ZnO coatings are already obtained after 50 ALD cycles, whereas at lower ALD cycles an island growth mode is observed. Moreover, the process allows for a uniform growth from the top to the bottom of the vertically aligned N-CNT arrays. X-ray photoelectron spectroscopy demonstrates that ZnO nucleation takes place at the N-containing species on the surface of the CNTs by the formation of the Zn-N bonds at the interface between the CNTs and the ZnO film.
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Affiliation(s)
- R M Silva
- Department of Materials and Ceramic Engineering, CICECO, University of Aveiro , 3810-193 Aveiro, Portugal
- Institut für Chemie, Humboldt-Universität zu Berlin , Brook-Taylor-Str. 2, 12489 Berlin, Germany
| | - M C Ferro
- Department of Materials and Ceramic Engineering, CICECO, University of Aveiro , 3810-193 Aveiro, Portugal
| | - J R Araujo
- Materials Metrology Division, INMETRO , 25250-020, Duque de Caxias, RJ, Brazil
| | - C A Achete
- Materials Metrology Division, INMETRO , 25250-020, Duque de Caxias, RJ, Brazil
- Programa de Engenharia Metalurgica e de Materiais, COPPE-UFRJ Rio de Janeiro , CP68501, 21945 Rio de Janeiro, RJ, Brazil
| | - G Clavel
- Institut für Chemie, Humboldt-Universität zu Berlin , Brook-Taylor-Str. 2, 12489 Berlin, Germany
| | - R F Silva
- Department of Materials and Ceramic Engineering, CICECO, University of Aveiro , 3810-193 Aveiro, Portugal
| | - N Pinna
- Institut für Chemie, Humboldt-Universität zu Berlin , Brook-Taylor-Str. 2, 12489 Berlin, Germany
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11
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Acauan L, Dias AC, Pereira MB, Horowitz F, Bergmann CP. Influence of Different Defects in Vertically Aligned Carbon Nanotubes on TiO2 Nanoparticle Formation through Atomic Layer Deposition. ACS APPLIED MATERIALS & INTERFACES 2016; 8:16444-16450. [PMID: 27269125 DOI: 10.1021/acsami.6b04001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The chemical inertness of carbon nanotubes (CNT) requires some degree of "defect engineering" for controlled deposition of metal oxides through atomic layer deposition (ALD). The type, quantity, and distribution of such defects rules the deposition rate and defines the growth behavior. In this work, we employed ALD to grow titanium oxide (TiO2) on vertically aligned carbon nanotubes (VACNT). The effects of nitrogen doping and oxygen plasma pretreatment of the CNT on the morphology and total amount of TiO2 were systematically studied using transmission electron microscopy, Raman spectroscopy, and thermogravimetric analysis. The induced chemical changes for each functionalization route were identified by X-ray photoelectron and Raman spectroscopies. The TiO2 mass fraction deposited with the same number of cycles for the pristine CNT, nitrogen-doped CNT, and plasma-treated CNT were 8, 47, and 80%, respectively. We demonstrate that TiO2 nucleation is dependent mainly on surface incorporation of heteroatoms and their distribution rather than structural defects that govern the growth behavior. Therefore, selecting the best way to functionalize CNT will allow us to tailor TiO2 distribution and hence fabricate complex heterostructures.
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Affiliation(s)
- Luiz Acauan
- Department of Materials, Federal University of Rio Grande do Sul , Porto Alegre, RS 90040-060, Brazil
- Department of Aeronautics and Astronautics, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Anna C Dias
- Department of Materials, Federal University of Rio Grande do Sul , Porto Alegre, RS 90040-060, Brazil
- Department of Chemical Engineering, Federal University of Rio Grande do Sul , Porto Alegre, RS 90040-060, Brazil
| | - Marcelo B Pereira
- Institute of Physics, Federal University of Rio Grande do Sul , Porto Alegre, RS 90040-060, Brazil
| | - Flavio Horowitz
- Institute of Physics, Federal University of Rio Grande do Sul , Porto Alegre, RS 90040-060, Brazil
| | - Carlos P Bergmann
- Department of Materials, Federal University of Rio Grande do Sul , Porto Alegre, RS 90040-060, Brazil
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12
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Stano KL, Faraji S, Hodges R, Yildiz O, Wells B, Akyildiz HI, Zhao J, Jur J, Bradford PD. Ultralight Interconnected Metal Oxide Nanotube Networks. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2016; 12:2432-8. [PMID: 26969860 DOI: 10.1002/smll.201503267] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 02/04/2016] [Indexed: 05/11/2023]
Abstract
Record-breaking ultralow density aluminum oxide structures are prepared using a novel templating technique. The alumina structures are unique in that they are comprised by highly aligned and interconnected nanotubes yielding anisotropic behavior. Large-scale network structures with complex form-factors can easily be made using this technique. The application of the low density networks as humidity sensing materials as well as thermal insulation is demonstrated.
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Affiliation(s)
- Kelly L Stano
- Department of Textile Engineering, Chemistry and Science, College of Textiles, North Carolina State University, Raleigh, NC, 27695, USA
| | - Shaghayegh Faraji
- Department of Textile Engineering, Chemistry and Science, College of Textiles, North Carolina State University, Raleigh, NC, 27695, USA
| | - Ryan Hodges
- Department of Textile Engineering, Chemistry and Science, College of Textiles, North Carolina State University, Raleigh, NC, 27695, USA
| | - Ozkan Yildiz
- Department of Textile Engineering, Chemistry and Science, College of Textiles, North Carolina State University, Raleigh, NC, 27695, USA
| | - Brian Wells
- Department of Textile Engineering, Chemistry and Science, College of Textiles, North Carolina State University, Raleigh, NC, 27695, USA
| | - Halil I Akyildiz
- Department of Textile Engineering, Chemistry and Science, College of Textiles, North Carolina State University, Raleigh, NC, 27695, USA
| | - Junjie Zhao
- Department of Chemical and Biomolecular Engineering, College of Engineering, North Carolina State University, Raleigh, NC, 27695, USA
| | - Jesse Jur
- Department of Textile Engineering, Chemistry and Science, College of Textiles, North Carolina State University, Raleigh, NC, 27695, USA
| | - Philip D Bradford
- Department of Textile Engineering, Chemistry and Science, College of Textiles, North Carolina State University, Raleigh, NC, 27695, USA
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Stano KL, Carroll M, Padbury R, McCord M, Jur JS, Bradford PD. Conformal atomic layer deposition of alumina on millimeter tall, vertically-aligned carbon nanotube arrays. ACS APPLIED MATERIALS & INTERFACES 2014; 6:19135-19143. [PMID: 25275708 DOI: 10.1021/am505107s] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Atomic layer deposition (ALD) can be used to coat high aspect ratio and high surface area substrates with conformal and precisely controlled thin films. Vertically aligned arrays of multiwalled carbon nanotubes (MWCNTs) with lengths up to 1.5 mm were conformally coated with alumina from base to tip. The nucleation and growth behaviors of Al2O3 ALD precursors on the MWCNTs were studied as a function of CNT surface chemistry. CNT surfaces were modified through a series of post-treatments including pyrolytic carbon deposition, high temperature thermal annealing, and oxygen plasma functionalization. Conformal coatings were achieved where post-treatments resulted in increased defect density as well as the extent of functionalization, as characterized by X-ray photoelectron spectroscopy and Raman spectroscopy. Using thermogravimetric analysis, it was determined that MWCNTs treated with pyrolytic carbon and plasma functionalization prior to ALD coating were more stable to thermal oxidation than pristine ALD coated samples. Functionalized and ALD coated arrays had a compressive modulus more than two times higher than a pristine array coated for the same number of cycles. Cross-sectional energy dispersive X-ray spectroscopy confirmed that Al2O3 could be uniformly deposited through the entire thickness of the vertically aligned MWCNT array by manipulating sample orientation and mounting techniques. Following the ALD coating, the MWCNT arrays demonstrated hydrophilic wetting behavior and also exhibited foam-like recovery following compressive strain.
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Affiliation(s)
- Kelly L Stano
- Department of Textile Engineering, Chemistry and Science, North Carolina State University , Raleigh, North Carolina 27695-8301, United States
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14
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Zhang Y, Utke I, Michler J, Ilari G, Rossell MD, Erni R. Growth and characterization of CNT-TiO2 heterostructures. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2014; 5:946-55. [PMID: 25161830 PMCID: PMC4142836 DOI: 10.3762/bjnano.5.108] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 06/12/2014] [Indexed: 05/28/2023]
Abstract
A thriving field in nanotechnology is to develop synergetic functions of nanomaterials by taking full advantages of unique properties of each component. In this context, combining TiO2 nanocrystals and carbon nanotubes (CNTs) offers enhanced photosensitivity and improved photocatalytic efficiency, which is key to achieving sustainable energy and preventing environmental pollution. Hence, it has aroused a tremendous research interest. This report surveys recent research on the topic of synthesis and characterization of the CNT-TiO2 interface. In particular, atomic layer deposition (ALD) offers a good control of the size, crystallinity and morphology of TiO2 on CNTs. Analytical transmission electron microscopy (TEM) techniques such as electron energy loss spectroscopy (EELS) in scanning transmission mode provides structural, chemical and electronic information with an unprecedented spatial resolution and increasingly superior energy resolution, and hence is a necessary tool to characterize the CNT-TiO2 interface, as well as other technologically relevant CNT-metal/metal oxide material systems.
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Affiliation(s)
- Yucheng Zhang
- Electron Microscopy Center, EMPA, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland
| | - Ivo Utke
- Laboratory of Mechanics of Materials and Nanostructure, EMPA, Swiss Federal Laboratories for Materials Science and Technology, Feuerwerkstrasse 39, CH-3602 Thun, Switzerland
| | - Johann Michler
- Laboratory of Mechanics of Materials and Nanostructure, EMPA, Swiss Federal Laboratories for Materials Science and Technology, Feuerwerkstrasse 39, CH-3602 Thun, Switzerland
| | - Gabriele Ilari
- Electron Microscopy Center, EMPA, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland
| | - Marta D Rossell
- Electron Microscopy Center, EMPA, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland
| | - Rolf Erni
- Electron Microscopy Center, EMPA, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland
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15
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Bachmann J. Atomic layer deposition, a unique method for the preparation of energy conversion devices. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2014; 5:245-248. [PMID: 24778945 PMCID: PMC3999862 DOI: 10.3762/bjnano.5.26] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 10/28/2013] [Indexed: 06/03/2023]
Affiliation(s)
- Julien Bachmann
- Institute of Inorganic Chemistry, Friedrich-Alexander University of Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany
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