Carbon and Oxide Nanostructures

Carbon Nanotubes (CNTs) have attracted the attention of scientific community due to their fundamental and technical importance. The structural diversities and the related diverse physical properties with large aspect ratio, small diameter and low density, are extremely fascinating. CNTs can behave as metallic conductors, semiconductors or insulators depending on their chirality, diameter and presence of defects. Their nano-scale dimension can be exploited as they have high accessible surface areas that make them not only exhibit high electronic conductivity but also useful mechanical properties. This chapter discusses on the production of CNTs, both single wall nanotubes and multiwall nanotubes giving emphasis on pulsed laser technique and microwave assisted chemical vapor deposition technique. The word wizard is coined due to their remarkable properties leading to their potential applications which are likely to stretch across different areas of industry.

The field of nanotechnology continues to develop. Carbon based materials with different structure and dimensions become increasingly important in the field. Carbon nanotubes (CNTs) are particularly promising due to their anisotropic extraordinary electrical, thermal and mechanical properties that have captured the imagination of researchers worldwide. However, the complexity involved in synthesis of nanotubes in a predictable manner has held back the development of real-world carbon nanotube based applications. In this chapter the structure and synthesis methods will be discussed of CNTs and other forms of nanostructures of carbons. Furthermore, their structuring into macroscopic assemblies, like mats and fibres will be presented as it has important role in future industrial applications of these materials.

The application of fullerene as a negative resist was first studied by Tada and Kanayama who verified that this material could be used as a negative electron beam resist. Its small molecule enables the resist to have a resolution of at least 20 nm. Robinson et al. demonstrated that chemical modification of C60 by adding functional groups to the C60 cage can significantly enhance the resist properties. Chemical amplification of the fullerene derivatives improves their sensitivities while maintaining their high resolution. In this chapter, the concepts of lithography and lithography techniques which include electron beam lithography technology systems are described. Current electron beam resists and their characteristics are discussed. A review of the application of fullerene and its derivatives as electron beam resists is presented. Finally, concepts of chemical amplification and current chemically amplified resists are discussed.Device density of modern computer components has grown exponentially as predicted by Moore’s Law [1] with a decrease in components sizes. Smaller devices mean a reduced interconnect length, reducing the distance electrons have to travel and thus signal delay. Although photolithography has been the technique of choice for the fabrication of microdevices for many years, electron beam lithography is a very promising lithographic technique for nanoscale patterning due to its flexibility and nearly unlimited resolution capability, able to fabricate sub-50 nm features. A factor that influences its resolution is the electron beam resists. The application of fullerene as a negative resist was first studied by Tada and Kanayama [2] who verified that this material could be used as a negative electron beam resist. Its small molecule enables the resist to have a resolution of at least 20 nm. Robinson et al. [3‐5] demonstrated that chemical modification of C60 by adding functional groups to the C60 cage can significantly enhance the resist properties. Chemical amplification of the fullerene derivatives improves their sensitivities while maintaining their high resolution [6, 7]. In this chapter, the concepts of lithography and lithography techniques which include electron beam lithography technology systems are described. Current electron beam resists and their characteristics are discussed. A review of the application of fullerene and its derivatives as electron beam resists is presented. Finally, concepts of chemical amplification and current chemically amplified resists are discussed.

In recent years, a lot of work has been focused on the synthesis of novel materials, clusters, and molecules which are unique in many ways. Numerous attempts to synthesize the theoretically predicted solids have been published. This chapter summarised the carbon materials in various forms; crystalline and non-crystalline. Carbon constitutes a class of new materials with a wide range of compositions, properties, and performance. Due to its unique optical and electrical properties, carbon has potential applications in vast fields especially in semiconductor devices. The structure and properties of the various crystalline carbon materials are reviewed. Related carbon based materials such as fullerenes, carbon fiber, glassy carbon, carbon black, amorphous carbon, diamond, graphite and buckminsterfullerene mentioned briefly as well as carbon nanotubes (CNTs). The CNTs preparation and characterization methods are presented and discussed in depth. However, it can be stated that a fascinating new field in the area of carbon has been discovered, which gives motivation for further studies dedicated to fundamental questions as well as the exploitation of the novel materials for industrial applications.

Hydrogenated amorphous carbon (a-C:H) thin film is one of the most studied materials due to its unique features. The a-C:H thin film is a remarkable material because of its novel optical, mechanical and electrical properties and its similarities to diamond. In this chapter we reviewed the structural and optical properties of hydrogenated amorphous carbon (a-C:H) thin films prepared in a DC-PECVD reactor. Both power and ion bombardment energy were continuously changed during the deposition, as a results of varying deposition parameters such as chamber pressure, electrode distance, CH₄ flow rate, and substrate temperature. The films properties ranged from polymer-like to graphite-like a-C:H films, as the power and ion energy increased. The structure and the optical properties of a-C:H films were analyzed by infrared and Raman spectroscopy, UV–Vis Spectrophotometer and photoluminescence. This is to extract the information on sp³/sp² and hydrogen contents, optical gap, E₀ and photoluminescence properties of a-C:H films. The films were found to consist of sp² clusters of which the size increases with increasing power and ion bombardment energy during the deposition, resulting in lower hydrogen, sp³ content, optical gap and photoluminescence response. The increased in hydrogen termination from the films at higher ion energies results in bigger cluster size and produced graphitic films.

The semiconducting polymer thin film has gained substantial interest in the research community because of the possibility to produce polymer based photovoltaic devices by roll to roll type manufacture, which is impossible by conventional technologies. Hole transferring semiconducting polymer and electron accepting fullerene (C₆₀) derivative are of special interest because of their stability and high power conversion efficiencies. With the discovery of new carbon “carbon nanotubes” (CNTs), researchers have started blending them with polymer for improving the solar cell efficiency. CNT-incorporated solar cell shows better power conversion efficiency than pristine solar cell without CNTs. This is because of the wonderful properties of CNTs. CNTs have outstanding properties like ballistic conductive, high aspect ratio, high surface area, flexible, strong, rigid, environmental stable, capability of charge dissociation, transportation and so on, which are believed to be an ideal material for fabricating high performance solar cell. In this chapter, some of the works done on polymer–CNTs based solar cells are summarized. A variety of device architecture and band diagram proposed by different authors have been included and described.

Carbon nanofiber (CNF) has been extensively produced as it shows outstanding physical properties which can be exploited in many applications. In addition to a long and straight nanofiber, several irregular configurations of CNF could be observed in a certain particle catalyst, reaction conditions and experimental techniques. One of the ways is by synthesizing carbon nanofiber using catalytic chemical vapor decomposition (C-CVD) method. This can be achieved by using Fe₂O₃ and NiO as the catalysts with ethylene and hydrogen as the carbon feedstock and carrier gas, respectively. The results from TEM analysis show that irregular CNF configurations are formed such as coiled, regular helical and twisted coil as well as corrugated CNF.

The aim of this chapter is to discuss the role of computer simulation in the domain of nano materials with a special emphasis on carbon nanotube. In recent years, nanotubes have been a major focus of nanoscience and nanotechnology. It is a self-growing field of study attracting tremendous interest, insight and effort in research and development around the world for its multi domain applications. Nanotube has been discovered a decade ago. With lots of its potentiality it is still hard to rationalize the structure property correlation, which is otherwise impossible without using computer modeling. Molecular modeling is a method, which combines computational chemistry techniques with graphics visualization for simulating and predicting three-dimensional structures, chemical processes, and physico-chemical properties of molecules and solids. The current chapter while covering the issues of electronic structural issues of nanotubes will especially focuses on the sensing issue. It will cover the role of reactivity index to design new carbon nanotubes efficient for sensing or storage capability at par with the global concern of environmental safety. We wish to show the capability of molecular modeling as a state of art to design new futuristic materials of interest to satisfy industrial needs.

In this chapter we review some aspects of the synthesis and characterisation of chemical vapor deposited diamond. Chemical Vapor Deposited (CVD) diamond is arguably the first of the “new” carbon materials that has received extensive research attention due to its potential industrial applications. Intense research activities on CVD diamond that spanned over 30 years brought much progress in understanding and techniques on the synthesis and laboratory demonstration of applications. However, industrial scale applications are still elusive, mainly due to the many technical hurdles that must be overcome in order to fully benefit from the wonderful properties of diamond. Although CVD diamond has been superseded by fullerene in the 1990s, later carbon nanotubes and more recently the emergence of graphene, it is worth looking at this fascinating form of synthetic diamond which may yet make a comeback in years to come. Attention was given to the established techniques for the synthesis and characterisation of CVD diamond as well as issues related to the challenges of industrial applications of CVD diamond.

Development of novel devices depends on the size, structure and controlled morphology of nanomaterials. Understanding the growth parameters and growth mechanism of nanostructured materials is essential. ZnO is one of the most promising and important semiconductor materials for its semiconducting characteristics. Variety of ZnO nanostructures such as nanowires, nanorods, nanotubes, nanorings, nanohelixes, nanosprings, nanobelts can be prepared by using a solid–vapour method, vapour liquid solid method and hydrothermal methods under specific growth conditions. ZnO clearly demonstrates its versatility in its structures and characteristics. This chapter also reviews the novel nanostructures of ZnO synthesized by solid–vapour method, vapour–liquid–solid method and hydrothermal method and their growth mechanisms. The applications of ZnO nanostructures as gas sensing, field effect transistors, solar cell, piezoelectric and EM detector is discussed.

This chapter has been written as an introductory on the preparation method of supported iron and cobalt oxides nanocatalysts. It begins with an overview on the gas-to-liquid (GTL) process. Emphasis is given on the catalysis for Fischer–Tropsch (FT) synthesis. Both the iron and cobalt-based catalysts have their own merits and features of these catalyst systems are highlighted. The spherical-model catalyst approach has been adopted as it can bridge the gap between the well-defined single crystal surfaces and those poorly-defined complex industrial catalysts. The synthesis methods for the oxide-supported nanoparticles of iron and cobalt oxides described in this chapter include the colloidal, reverse microemulsion, ammonia deposition, impregnation, precipitation and strong electrostatic adsorption. The applications of electron microscopy techniques on the morphological characterization of supported nanoparticles are illustrated in this chapter.

The projected increase in human population has triggered the comprehensive search for suitable renewable energy related electrical power generation technologies. The efforts to exploit these technologies dates back to the last century, but breakthroughs certainly fall short in terms of competition with the current fossil fuel based energy systems. One of the strong points that allow solar energy to remain competitive is the fast deterioration of the environment and the accompanying natural disasters linked to the extensive usage of fossil-fuels. Concepts such as energy efficiency and energy conservation must be converted to strategies and initiatives, leveraging on nanotechnology as one of the important elements in solar hydrogen production. Although solar hydrogen production concept is not new, but the issues such as effective energy balance and management have been hindering the implementation process. The practicality and total energy management studies must be able to facilitate the sustainable implementation of solar hydrogen related electrical power generation systems. In this chapter, an Integrated Nano-Solar Hydrogen Production Scheme is discussed.

To date, nano-magnetic materials have gain great attention by the research community due to their importance for future applications. A brief introduction of Fe–FeO nanocomposites in the form of particles and thin films is given in the first part of this chapter. This includes definition, magnetic properties, preparation, structure and applications. Different preparation methods of Fe–FeO are then introduced in the second part of the chapter. These include mechanical alloying, high energy ball milling, mechanochemical processing, DC magnetron sputtering, molecular-beam-epitaxy, plasma gas condensation. Among these preparation techniques, mechanochemical processing has been fully explained. Different techniques and instruments which have been used to characterize the samples have been explained. These include XRD, TEM, VSM, Superconducting Quantum Interferences Devices (SQUID), and Mössbauer. Magnetic properties of the nanocomposites especially Fe–FeO have been presented in the final part of the chapter. These include magnetization, coercivity, Mössbauer, hysteresis loops, exchange bias effect, vertical shift, spin glass phase, rotational hysteresis, FC and ZFC hysteresis loops.

The development of nanoscale materials for optical chemical sensing applications has emerged as one of the most important research areas of interest over the past decades. In this chapter we firstly present some general aspects of nanostructured materials and give a description on the analytical aspects of sensors and sensing principles. The broad variety of nanomaterials as well as sensors’ design made us to limit our presentation, which concentrates on nanomaterials, such as quantum dots, polymer- and sol-gel-based particles. The benefits and drawbacks of the properties of these nanomaterials used in optical sensing applications are given, and the recently developed optical chemical sensors and probes based on photoluminescence are overviewed. Finally, some future trends of the nanomaterial-based optical chemical sensors are given.

The preparation and characterization of zinc oxide (ZnO) nanostructured thin films have been discussed. ZnO, a wide band gap semiconductor material, has proven to be of great interest for use in a lot of applications especially in electronics and green technology such as solar cells, sensors and light emitting devices. With wide applications by ZnO material, it is important to study its preparation and properties which could give the characteristics that suitable in applications. In this study, we prepared ZnO nanostructured thin films using economically viable and simple technique of sol-gel spin-coating technique. The effects of annealing temperature and precursor molar concentration on ZnO nanostructured properties are investigated. We characterized and discussed the morphology, crystallinity, optical and electrical properties of prepared ZnO nanostructured thin film.

Nanoscaled magnetic materials are great candidates for fundamental and applied research. 0D, 1D and 2D magnetic nanostructures have been extensively studied previously. One of the unique phenomena that only exists in nanoscaled magnetic structure (below a certain critical size) is superparamagnetism. In this chapter, various chemical synthesis methods to obtain superparamagnetic nanoparticles are compared. Strategies to prevent agglomeration of nanoparticles and the influent factors for nanoparticle synthesis are discussed. Three examples in biomedical application are introduced and a concluding remark for future synthesis approaches is highlighted.

Ammonia production is a very energy- and capital-intensive industry as it requires high temperature (400–500°C) and also high pressure (150–300 bar) for its daily operations. Two moles of ammonia are obtained by reacting one mole of nitrogen and three moles of hydrogen gases in the presence of conventional catalyst which is magnetite. The process to produce ammonia is known as Haber–Bosch process which was developed and patented by Fritz Haber and Carl Bosch in 1916. Since then more work on ammonia production was carried out with the aim to obtain higher ammonia yield. Catalytic reaction giving emphasis on types of catalysts was reviewed in this chapter. Different catalysts synthesis methods and their characterisations were also reviewed A variety of microreactors were proposed by different authors and some patent fillings have been described. A new method to synthesize ammonia at room temperature and ambient pressure were described. The reaction was done in 1 T magnetic field. This work offers the ammonia producers a potential contender in the market place.