1,204 research outputs found
Dataset supporting the University of Southampton Doctoral Thesis "Organic and inorganic perovskite solar cells: Design, fabrication and performance analysis"
No full textDataset supporting the University of Southampton Doctoral Thesis "Organic and inorganic perovskite solar cells: Design, fabrication and performance analysis".
The dataset includes data for the figures from Figure 4-1 to Figure 4-11 which was collected using CASTEP software.The other figures were created employing Origin software.
Data can be accessed under CC BY license
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Kinetics of alkali metal ion exchange into nanotubular and nanofibrous titanates
No full textThe kinetics of intercalation of Li+, Na+, K+ and Cs+ cations between the layers of titanate nanotubes and nanofibres have been studied in an aqueous suspension of nanotubes at 25ºC. The rate of intercalation was found to be similar for different cations and depended on the length of the nanotubes. The decrease in nanotube length resulted in a higher rate of ion-exchange, indicating that the transport of cations in titanate nanotubes occurred probably along their length. In contrast, the transport of cations in titanate nanofibres probably dominated in the direction perpendicular to length. Correlations between the rate of intercalation and the crystal structure modification following intercalation have been established for nanotubular and nanofibrous titanates
Titanate and Titania Nanotubes: Synthesis, Properties and Applications
No full textContentsAbbreviations ixList of symbols xiChapter 1 Introduction and Scope 1
1.1 The history of nanomaterials 1
1.1.1 The importance of TiO2 and titanate nanomaterials 3
1.2 Classification of the structure of nanomaterials 5
1.3 Synthesis of important elongated nanomaterials 7
1.3.1 Metal oxide nanotubes 7
1.3.2 Metal chalcogenide nanotubes 12
1.3.3 Mixed oxides, silicates and other compounds as nanotubes 13
1.4 Techniques and instruments used to study nanomaterials 15
References: 16Chapter 2 Synthesis Techniques and the Mechanism of Growth 19
2.1 Template methods 19
2.2 Alkaline hydrothermal synthesis of elongated titanates 23
2.2.1 Alkaline hydrothermal synthesis of titanate nanotubes and nanofibres 24
2.2.2 Mechanism of nanostructure growth 26
2.2.3 Methods to control the morphology of nanostructures 33
2.3 Electrochemical (anodic) oxidation 35
2.3.1 Principles and examples 35
2.3.2 Mechanism of nanotube growth 38
2.3.3 Methods to the control the morphology of nanotubes 40
2.4 Conclusions 42
References 43Chapter 3 Structural and Physical Properties of Elongated TiO2 and Titanate Nanostructures 47
3.1 Crystallography 47
3.1.1 Crystallography of titanate nanotubes 47
3.1.2 Crystallography of titanate nanofibres, nanorods and nanosheets 51
3.1.3 Crystallography of anodized and template assisted TiO2 52
3.1.4 Conclusions 52
3.2 Adsorption, surface area and porosity 53
3.2.1 Surface area of nanotubes 53
3.2.2 Pore volume of nanotubes 56
3.2.3 Effect of ionic charge on adsorption from aqueous solutions 59
3.3 Electronic structure of titanate nanotubes 61
3.3.1 Spectroscopy of titanate nanotubes: UV-Vis, Pl, ESR, XPS, NMR, Raman and FTIR 63
3.3.2 Electrical-, proton- and thermal conductivities of titanate nanotubes 70
3.4 Physical properties of TiO2 nanotube arrays 71
References 73Chapter 4 Chemical Properties, Transformation and Functionalization of Elongated Titanium Oxide Nanostructures 77
4.1 Thermodynamic equilibrium between the nanotube and its environment 77
4.2 Ion-exchange properties of nanostructured titanates 80
4.2.1 Kinetic characteristics of ion-exchange 80
4.2.2 Decoration of nanotubes using using the ion-exchange method 86
4.2.3 Decoration of substrates with nanotubes 88
4.3 Surface chemistry and functionalization of nanostructured titanates 91
4.4 Stability of nanotubes and phase transformations 92
4.4.1 Thermal stability 92
4.4.2 Acidic environments 95
4.4.3 Mechanical treatment 95
References 95Chapter 5 Potential Applications 98
5.1 Energy conversion and storage 98
5.1.1 Solar cells 98
5.1.2 Lithium batteries 101
5.1.3 Fuel cells and batteries 104
5.1.4 Hydrogen storage and sensing 107
5.2 Catalysis, electrocatalysis and photocatalysis 108
5.2.1 Reaction catalysis 108
5.2.2 Supercapacitors and general electrochemistry 115
5.2.3 Photocatalysis in elongated titanates and TiO2 117
5.3 Magnetic materials 124
5.4 Drug delivery and bio-applications 125
5.5 Composites, surface finishing and tribological coatings 126
5.6 Other applications 128
References 128<br/
Elongated titanate nanostructures and their applications
No full textRecent advances in the synthesis, characterisation and applications of elongated titanates and TiO2 nanostructures (including nanotubes, nanofibres and nanorods) are reviewed. The physico-chemical properties of nanostructures, such as high surface area, efficient ion-exchanged properties, electron and proton conductivity and high aspect ratio, are described in connection with a particular application. Practical aspects of the preparation, stability and transformation of elongated titanates are considered. A critical survey of the literature is provided together with the development of prospective energy applications of elongated titanates in catalysis, photocatalysis, electrocatalysis, solar cells, fuel cells, lithium batteries and hydrogen storage. Other applications utilising the high aspect ratio of elongated nanostructures include biomedical implants, sensors, drug delivery systems and smart, tribological composite coatings
The Energy Harvesting Performance of a Flexible Triboelectric-Based Electrospun PTFE/PVDF Fibre
No full textA triboelectric power generator/energy harvester is an attractive option for mechanical energy harvesting for smart, wearable applications. This paper reports on the fabrication and evaluation of the energy harvesting performance of Polytetrafluoroethylene/Polyvinylidene Fluoride (PTFE/PVDF) fibre prepared using a one-step electrospinning technique. Different concentrations (0, 1, 2, 3, and 4%wt.) of the 1 μm PTFE powder in the electrospun PVDF fibre were investigated. The electrospun fibre was assembled into a nonwoven fabric mat and tested in the vertical contact separation triboelectric mode by constructing a sandwich structure with electrodes in a book-shaped assembly. The voltage output from the cyclical compressive test for fibres with 4%wt. PTFE in PVDF was five times greater than it was for the 100% PVDF electrospun fibres. The influence of adding nylon fabric as a triboelectric donor material within the assembly was explored. The output of the 4%wt. PTFE/PVDF sample was then tested with and without nylon fabric at different frequencies (3–12 Hz). The results show a further 80% increase in the output voltage with the additional nylon fabric included, and the harvester was able to illuminate up to 95 LEDs
The stability of halloysite nanotubes in acidic and alkaline aqueous suspensions
No full textThe long term stability of natural halloysite nanotubes was studied at room temperature (22 ± 2 ºC) in pure water, acidic and basic aqueous suspensions. The structural and morphological transformations of nanotubes were studied by TEM, SEM, nitrogen adsorption, XRD Raman and FTIR spectroscopy accompanied by monitoring the concentration of dissolved Si(IV) and Al(III) in solution. It has been revealed that, in 1 mol dm-3 H2SO4 solution, the dissolution of halloysite is initiated on the inner surface of nanotubes leading to formation of amorphous spheroidal nanoparticles of SiO2 whereas, in 1 mol dm-3 NaOH solution, dissolution of inner surface of nanotubes is accompanied by formation of Al(OH)3 nanosheets
Hierarchical tube-in-tube structures prepared by electrophoretic deposition of nanostructured titanates into TiO2 nanotubes array
No full textMultiwalled nanotubular titanates have been incorporated inside the pores of a wide TiO2 nanotube array using electrophoretic deposition under vigorous stirring. The resulting hierarchical electrodes combine both benefits of open channels for rapid transport of ions and high specific surface area
Metastable nature of titanate nanotubes in an alkaline environment
No full textA systematic analysis of the effect of composition and temperature of a NaOH/KOH binary aqueous mixture on the morphological properties of titanate nanostructures formed under alkaline hydrothermal transformation of TiO2 at atmospheric conditions has been performed using HRTEM techniques. All observed nanostructures, including nanosheets, nanotubes, nanofibres and nanoparticles, have been mapped over a wide range of composition (from pure NaOH to pure KOH) and temperature (from 50 ºC to 110 ºC). Attempts to intensify the TiO2 transformation by addition of titanate nanotubes seeds or agitation of the reaction mixture have resulted in formation of thermodynamically stable nanofibres rather than nanotubes. The effects of kinetic and thermodynamic control of the reaction are discussed regarding the transformation of TiO2 to nanosheets, nanotubes and nanofibres
Control over the hierarchical structure of titanate nanotube agglomerates
No full textAn alkaline hydrothermal treatment of several types of ordered macroporous TiO2 structures, namely microtubes, sea urchin shapes and anodic nanotubes array has been investigated under stationary conditions. The effect of the size and geometry of these structures on the morphology of forming hierarchical agglomerates of titanate nanotubes have been systematically studied. It has been revealed that at sizes larger than the critical value (ca. 1 ?m), the whole geometry of the initial ordered TiO2 structure is maintained under reaction conditions leading to formation of hierarchical structures, in which bulk TiO2 is replaced with titanate nanotube agglomerates. This principle provides a convenient route for the preparation of multi-scale micro- and nanostructures of TiO2 based materials. The analysis of critical size suggests that under reaction conditions, due to the limited transport of dissolved Ti(IV) species, the growth of nanotubes occurs locally
Low-temperature synthesis of titanate nanotubes in aqueous KOH
No full textAlthough hydrothermal alkaline treatment of TiO2 in a concentrated, aqueous solution of KOH usually results in the
formation of solid fibrous titanates, analysis of the temperature dependence of Ti(iv) concentration in KOH solution and
comparison of these data with that for NaOH solution suggests that, at low temperatures, the treatment of TiO2 with KOH
may result in formation of titanate nanotubes. This result was confirmed by 12 days treatment of TiO2 in 10 mol dm?3
KOH at 56?C, resulting in the formation of nanotubular titanates with similar morphology to those produced in a shorter
time at higher temperatures using NaOH.The mechanism of nanotube formation and the necessary conditions of nanotube
phase formation are considered
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