Thermal conduction effects impacting morphology during synthesis of columnar nanostructured TiO2 thin films

An, Woo-Jin; Jiang, David D.; Matthews, James R.; Borrelli, Nicholas F.; Biswas, Pratim

doi:10.1039/c0jm04563b

Cited by 18 publications

(16 citation statements)

References 39 publications

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“…Nanostructured anatase solid coatings have been previously reported by only a few authors [32,33]. Column-like morphologies of TiO2 are commonly reported for rutile TiO2 [34] and similar structures have been reported for anatase nanocrystals [35]. Microscale plated-anatase crystals were reported from aerosol CVD [36].…”

Section: Discussionmentioning

confidence: 73%

Process-Induced Nanostructures on Anatase Single Crystals via Pulsed-Pressure MOCVD

2020

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The recent global pandemic of COVID-19 highlights the urgent need for practical applications of anti-microbial coatings on touch-surfaces. Nanostructured TiO 2 is a promising candidate for the passive reduction of transmission when applied to handles, push-plates and switches in hospitals.Here we report control of the nanostructure dimension of the mille-feuille crystal plates in anatase columnar crystals as a function of the coating thickness. This nanoplate thickness is key to achieving the large aspect ratio of surface area to migration path length. TiO 2 solid coatings were prepared by pulsed-pressure metalorganic chemical vapor deposition (pp-MOCVD) under the same deposition temperature and mass flux, with thickness ranging from 1.3-16 µm, by varying the number of precursor pulses. SEM and STEM were used to measure the mille-feuille plate width which is believed to be a key functional nano-dimension for photocatalytic activity. Competitive growth produces a larger columnar crystal diameter with thickness. The question is if the nano-dimension also increases with columnar crystal size. We report that the nano-dimension increases with the film thickness, ranging from 17-42 nm. The results of this study can be used to design a coating which has co-optimized thickness for durability and nano-dimension for enhanced photocatalytic properties.

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Section: Discussionmentioning

confidence: 73%

Process-Induced Nanostructures on Anatase Single Crystals via Pulsed-Pressure MOCVD

2020

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“…The branching of columnar nanostructures has previously been studied by our group in detail and has been attributed to the decrease in the tip surface temperature of the TiO 2 nanostructure due to thermal conduction effects as the column height increases. 22,23 This decrease in surface temperature results in a decrease in the sintering rates, thus leading to the formation of a branched structure. The branching of the nanostructures becomes observable by SEM for taller columns with height greater than 5 μm.…”

Section: Resultsmentioning

confidence: 99%

Model Based Analysis of One-Dimensional Oriented Lithium-Ion Battery Electrodes

Chadha

Suthar

Rife

et al. 2017

J. Electrochem. Soc.

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Oriented one-dimensional nanostructures have been of substantial interest as electrodes for lithium-ion batteries due to the better performance both in terms of initial capacity and lower capacity fade compared to powder pressed electrodes. This paper focuses on a model driven approach to understanding the relationship between the morphology of these oriented nanostructures to the performance of the battery. The Newman-type P2D modeling technique is applied to a porous electrode made up with solid continuous cylinders that extends from the current collectors to separator. TiO 2 columnar nanostructures of varying heights were synthesized using the aerosol chemical vapor deposition (ACVD) and their performance as electrodes in a lithium-ion battery was measured. This electrochemical transport model was validated with the experimental data. This model was used to understand the role of transport parameters, including the diffusivity of lithium in the TiO 2 and the electronic conductivity of the TiO 2 columns, and structural parameters, including the height of the columns and the porosity of the electrode, on the areal capacity of a lithium ion battery at different rates of discharge. The model enables for the prediction of optimized structural parameters of one-dimensional electrodes tailored to the desired application of lithium and sodium-ion batteries. Lithium-ion batteries (LiBs) have emerged as the dominant power source for most electronic applications today, as well as the most suitable candidates for electric vehicles and hybrid electric vehicles. The diverse range of applications for which LIBs are used demand both high energy densities and high power densities, although they are inversely related.1 Several research approaches have been adopted for increasing both the energy density and the power density of lithium ion batteries, and controlling the nanostructure of the electrode material has been one such widely adopted approach. One-dimensional (1D) nanostructures in particular have received considerable attention for both cathode and anode materials 3-5 due to the several advantages provided by the 1D nanostructures, which can enhance both the energy and the power density of the battery. These advantages include (1) the efficient electron transport pathway provided by the nanostructure, 6 (2) shorter ion diffusion path owing to the less tortuous path and the larger surface to volume ratio, 7 and (3) better strain relaxation due to the accommodation space in between the nanostructures.8 Recent research has focused on the direct growth of the 1D nanostructures on the current collector to obtain oriented nanostructures which further provide improved performance due to the direct attachment of each 1D nanostructure to the current collector ensuring their participation in the electrochemical reaction and obviating the need for any binding agent. Different applications of LiBs demand the optimization of their energy density and power density. While nanostructuring aims to maximize both the densities, further ...

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“…As illustrated in Fig. 9, thin film growth mechanisms in ACVD could be qualitatively explained in terms of τ sin and particle arrival time, t arv [85]. Within a boundary layer, deposited particles form structures with orientation [86,87].…”

Section: Aerosol Routes For Morphology Controlmentioning

confidence: 99%

The energy-environment nexus: aerosol science and technology enabling solutions

Biswas

Wang

2011

Front. Environ. Sci. Eng. China

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Energy issues are important and consumption is slated to increase across the globe in the future. The energy-environment nexus is very important as strategies to meet future energy demand are developed. To ensure sustainable growth and development, it is essential that energy production is environmentally benign. There are two temporal issues-one that is immediate, and needs to address the environmental compliance of energy generation from fossil fuel sources; and second that is the need to develop newer alternate and more sustainable approaches in the future. Aerosol science and technology is an enabling discipline that addresses the energy issue over both these time scales. The paper is a review of aspects of aerosol science and engineering that helps address carbon neutrality of fossil fuels. Advanced materials to meet these challenges are discussed. Future approaches to effective harvesting of sunlight that are enabled by aerosol studies are discussed.

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Thermal conduction effects impacting morphology during synthesis of columnar nanostructured TiO2 thin films

Cited by 18 publications

References 39 publications

Process-Induced Nanostructures on Anatase Single Crystals via Pulsed-Pressure MOCVD

Process-Induced Nanostructures on Anatase Single Crystals via Pulsed-Pressure MOCVD

Model Based Analysis of One-Dimensional Oriented Lithium-Ion Battery Electrodes

The energy-environment nexus: aerosol science and technology enabling solutions

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