Remarkably improved field emission of TiO2 nanotube arrays by annealing atmosphere engineering

Liao, Aizhen; Wang, Chengwei; Chen, Jianbiao; Zhang, Xuqiang; Li, Yan; Wang, Jian

doi:10.1016/j.materresbull.2015.06.036

Cited by 16 publications

(11 citation statements)

References 39 publications

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“…These results were consistent with the Mott-Schottky data, as changes in charge carrier density should correlate with the electrical conductivity. Our conductivities were also comparable with previously reported two-point measurements on anatase TiO2 nanotubes 38,71 . The conductivity measurements and Mott-Schottky analysis match up well with the theoretical models.…”

Section: Two-point Electrical Conductivity Resultssupporting

confidence: 91%

“…Each sample clearly had the associated spectrum for anatase TiO2, with peaks present at approximately 144 cm -1 , 395 cm -1 , 517 cm -1 , and 636 cm -1 . The peaks correspond to the Eg(1), B1g(1), B1g(2)+A1g, and Eg(3) vibrational modes, respectively 38,[90][91][92] . A small peak at 196 cm -1 associated with the Eg(2) vibrational mode was also present in all four samples 90,92 .…”

Section: Raman Spectroscopy Resultsmentioning

confidence: 99%

“…Phonon confinement, strain, and nonstoichiometry could all contribute to the development of the observed blueshift and broadening [91][92][93][94][95][96] . Dispersion caused by phonons will occur if the TiO2 crystallite size is less than 10-20 nm 38,51,91 . However, as discussed in Section 4.4, the crystallite size for all of the samples is 39-48 nm, which eliminates the possibility of phonon confinement.…”

Section: Raman Spectroscopy Resultsmentioning

confidence: 99%

“…The generation of point defects has also been shown to improve the electrochemical properties of TiO2. These defects can be introduced into the material through various techniques like substitutional doping and ion irradiation [33][34][35][36] have been shown to create oxygen vacancies [37][38][39][40] . The hydrogenation of TiO2 via H2 atmospheric treatment has also been used to generate oxygen vacancies 37,[41][42] .…”

Section: Point Defect Generationmentioning

confidence: 99%

“…Evidence of these factors are seen in literature, as there is a large variation in reported two-point conductivities of TiO2 nanotubes 38,[70][71][72] . Regardless of these shortcomings, this technique can be used to detail the general trends in sample conductivity.…”

Section: Figure 22 Equivalent Circuit Developed To Fit Data Obtainedmentioning

confidence: 99%

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The Effects of Atmospheric Heat Treatments on TiO2 Nanotube Anodes for Lithium-Ion Batteries

Savva¹

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for their helpful conversations regarding conductivity measurements, Raman spectroscopy, computational modeling, and band structure, respectively. I also would like to acknowledge the National Science Foundation (NSF) for the funding provided for this research (DMR-1408949). I would like to thank Matthew Lawson for his work on the computational modeling presented in this thesis. I also want to thank Ariel Weltner for her help with the two-point conductivity measurements. Furthermore, I would like to acknowledge the Electrochemical Energy Materials Lab, particularly Kassiopeia Smith, as well as the entire faculty and staff from the Department of Materials Science and Engineering for their help and support during my time at Boise State University. I want to thank Chris Jones, Hailey Bull, and Sterling Croft for their contributions towards this work as well.

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Section: Two-point Electrical Conductivity Resultssupporting

confidence: 91%

Section: Raman Spectroscopy Resultsmentioning

confidence: 99%

Section: Raman Spectroscopy Resultsmentioning

confidence: 99%

Section: Point Defect Generationmentioning

confidence: 99%

Section: Figure 22 Equivalent Circuit Developed To Fit Data Obtainedmentioning

confidence: 99%

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The Effects of Atmospheric Heat Treatments on TiO2 Nanotube Anodes for Lithium-Ion Batteries

Savva¹

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Electron Emission Devices for Energy‐Efficient Systems

Nirantar

Ahmed

Bhaskaran

et al. 2019

Advanced Intelligent Systems

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Artificial intelligence platforms, high-speed computation, and data handling systems increasingly need energy-efficient systems. Electron emission was fundamental to the development of transistors and electronics over seven decades ago. This technology has a renewed emergence and includes implications in diverse fields ranging from electronics, telecommunication, defense, space exploration, medical science, and material science to televisions and displays. For such a vital field, a critical review of theories, current research directions, applications, and future prospects is invaluable. Herein, the ongoing research directions adopted to enhance the emitter performance are reviewed and the relative degree of their success is compared. This is supported by an overview of key electron emission, transport mechanisms, and ways to tune a particular mechanism for energy-efficient applications. The diverse range of applications in this field, with a particular focus on electronics, is outlined. Exciting current developments in electron field emission that could revolutionize the electronic industry with a resurgence of nanoscale field emission transistor in the air medium are also discussed. Figure 2. Representation of different electron emission mechanisms: a) Comparison of thermionic emission, Schottky emission, FN tunnelling, and direct tunnelling with schematic energy band diagram. b) Typical thermionic emission plot. c) Typical Schottky plot. (b,c)Reproduced with permission. [3]

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Thermal Ramping Rate during Annealing of TiO₂ Nanotubes Greatly Affects Performance of Photoanodes

Raza

Hwang

Denisov

et al. 2021

Physica Status Solidi (a)

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Herein, highly ordered TiO2 nanotube (NT) arrays on a Ti substrate is synthesized in a fluoride‐containing electrolyte, using the electrochemical anodization method, which yields amorphous oxide tubes. The effects of different thermal annealing profiles for the crystallization of the amorphous TiO2 NTs are studied. It is found that the temperature ramping rate has a significant impact on the magnitude of the resulting photocurrents (incident photon‐to‐current conversion efficiency [IPCE]) from the tubes. No appreciable changes are observed in the crystal structure and morphology of the TiO2 NTs for different annealing profiles (to a constant temperature of 450 °C). The electrochemical properties of the annealed TiO2 NTs are investigated using intensity‐modulated photocurrent spectroscopy (IMPS), open‐circuit potential decay, and Mott–Schottky analysis. The results clearly show that the annealing ramping rate of 1 °C s−1 leads to the highest IPCE performance. This beneficial effect can be ascribed to a most effective charge separation and electron transport (indicating the least amount of trapping states in the tubes). Therefore, the results suggest that controlling the annealing ramping rate is not only a key factor affecting the defect structure but also a powerful tool to tailor the physical properties, and photocurrent activity of TiO2 NTs.

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Remarkably improved field emission of TiO2 nanotube arrays by annealing atmosphere engineering

Cited by 16 publications

References 39 publications

The Effects of Atmospheric Heat Treatments on TiO2 Nanotube Anodes for Lithium-Ion Batteries

The Effects of Atmospheric Heat Treatments on TiO2 Nanotube Anodes for Lithium-Ion Batteries

Electron Emission Devices for Energy‐Efficient Systems

Thermal Ramping Rate during Annealing of TiO₂ Nanotubes Greatly Affects Performance of Photoanodes

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Remarkably improved field emission of TiO2 nanotube arrays by annealing atmosphere engineering

Cited by 16 publications

References 39 publications

The Effects of Atmospheric Heat Treatments on TiO2 Nanotube Anodes for Lithium-Ion Batteries

The Effects of Atmospheric Heat Treatments on TiO2 Nanotube Anodes for Lithium-Ion Batteries

Electron Emission Devices for Energy‐Efficient Systems

Thermal Ramping Rate during Annealing of TiO2 Nanotubes Greatly Affects Performance of Photoanodes

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Thermal Ramping Rate during Annealing of TiO₂ Nanotubes Greatly Affects Performance of Photoanodes