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Über dieses Buch

This book discusses new trends in nanotechnology. It covers a wide range of topics starting from applications of nanomaterials in perovskite solar cells, pharmacy, and dentistry to self-assembled growth of GaN nanostructures on flexible metal foils by laser molecular beam epitaxy. It also includes other interesting topics such as advancement in carbon nanotubes; processing techniques, purification and industrial applications, metal di-chalcogenides for waste water treatment and recent advancement in nanostructured-based electrochemical genosensors for pathogen detection and many more. The book will be of great interest to researchers, professionals and students working in the areas of nanomaterials and nanotechnology.



1. Synthesis and Photocatalytic Properties of 2D Transition Metal Dichalcogenides

Nanotechnology is the emerging technology of the twenty-first century. It deals with the synthesis and investigation of ultrafine materials and their use in technology for numerous applications. It is an interdisciplinary field that combines the principles of physics, chemistry, and engineering, such as structural analysis, electrical engineering, mechanical design, computer science and systems engineering. Two-dimensional (2D) materials are crystalline materials consisting of layered arranged atoms or molecules. In the last few years, 2D materials have been extensively explored for their unique 2D geometry, high surface-to-volume ratio, and nanoscale thickness. Two-dimensional transition metal dichalcogenide (2D-TMDCs) materials have the common formula MX2, where X = sulfur (S), selenium (Se) or tellurium (Te), and M belongs to the elements of group of 4, 5, and 6 of the periodic table. MX2 layers are covalently bound by the van der Waals force between the layers. The weak van der Waals bonds between the layers facilitate separation of the layers to form 2D materials. Many synthesis methods, like as CVD, hydrothermal, and CVT method, have been used to synthesize the 2D-TMDCs materials. Titanium disulfide (TiS2) is an important layered material among the TMDCs family. It crystallizes in the hexagonal structure similar to CdI2. It is a multi-layered compound with repeating subunits formed from a layer of Ti atoms and a layer of S. TiS2 has a band gap varying between 0.05 and 2.5 eV; the Bohr’s radius of approximately 6.43 nm and the lattice parameter constants a (a = b) and c of TiS2 are 3.40 A°, 5.96 A° respectively. The present chapter deals with the review of research work reported on 2D metal dichalcogenides with a special emphasis of TiS2.
Mohd. Parvaz, Hasan Abbas, Zishan H. Khan

2. Studies on Dye-Sensitized Solar Cells Incorporated with Perovskite as Sensitizer Dye

Over the last two decades, researchers have focused research work on photovoltaics-based solar technologies. Among different photovoltaics technologies, hybrid (organic/inorganic) photovoltaic has witnessed an enormous research effort in past years, and the present, leading to the first commercial products. In this era of solar energy, dye-sensitized solar cells (DSSC) are also playing a pivotal role. However, the maximum efficiency of DSSC is stuck around 12-14%. Perovskite was first used as a sensitizer in dye-sensitized solid-state devices in which molecular dye was replaced by perovskite in 2009. Perovskite has been found too high light-harvesting property with a high absorption coefficient and charges transporting and accumulation properties as well. Thus, perovskite can be used either as a sensitizer or light harvester. An all-solid-state perovskite solar cell based on organolead iodide demonstrated 9.7% in 2012, and a year later, its efficiency increased to more than 15%, and now it becomes which is 28% in 2020, which implies that organolead halide perovskite is a promising solar cell material. The bandgap of 1.5 eV for CH3NH3PbI3 can be tuned by replacing A or B or X ions in the ABX3 perovskite structure within the allowed tolerance factors, which can further improve photovoltaic performance more than 20%. Since the perovskite layer is as thin as sub-micrometer levels, a perovskite solar cell can be classified as a new type of thin-film solar cell. Because of the demand and fascinating technology of DSSC solar cells, the present chapter focuses on the synthesis of light sensitizers, fabrication of dye/natural dye/perovskite-based solar cells, and its characterization in an ambient air atmosphere. The research work presented in this chapter may be useful for the scientific society working in the field of photovoltaic devices. This work includes the fabrication and characterization of dye, natural dye, and perovskite light sensitizer-based dye-sensitized solar cells. The use of dyes and perovskite sensitizers for developments of solar cells shall not only be cost-effective with a simpler technology of fabrication but also it will be eco-friendly.
Rahul, Sultan Ahmad, Pramod K. Singh, Zishan H. Khan

3. Nanomaterials: A Windfall to Dentistry

Nanotechnology has tremendous potential in the field of dentistry to provide a comprehensive oral health care with advanced nanomaterials, clinical devices, and advanced diagnostic tools. The impact of nanotechnology in oral health has enhanced the quality of dental care by manifolds. Nanomaterials in dental products can improve quality and have superior properties due to numerous active functional groups in nanomaterials. The nanodentistry is thus opening up new horizons for immense possibilities in dental research, but one should keep eyes on safety, efficacy, and implementation of nanotechnology. This chapter is a sincere effort to extend the horizons of nanomaterials and their windfall for dentistry.
Nafis Ahmad, Zeba Jafri, Asim Khan, Zishan H. Khan

4. Nanostructured Abrasive Materials for Ultraprecision Finishing of High-Performance Materials

This chapter focuses on the development of nanostructured abrasive materials that are required to produce engineered surfaces of the highest integrity possible when processing difficult-to-machine materials such as those used in the aerospace sector. The chapter describes the challenges manufacturers have when dealing with abrasive cutting tools that fail to maintain roundness and suffer from “wheel collapse,” and localized pitting that affects the roundness of the wheel and the integrity of the ground surface that eventually has to be rectified by dressing methods that are non-productive in terms of cycle time and generate waste products. Subsequent discussions focus on the manufacture and use of new abrasive products by fusion and sintering that are nanostructured such that wheel pitting is virtually eliminated, wheel collapse is rare, and cycle time is reduced when grinding difficult materials such nickel and titanium alloys. Case studies are referred to throughout the chapter as a way to explain how nanostructured materials can change the way abrasive materials operate especially in the aerospace sector and beyond.
M. J. Jackson

5. Self-assembled Growth of GaN Nanostructures on Flexible Metal Foils by Laser Molecular Beam Epitaxy

Low-dimensional semiconductor structures such as thin films, nanorods, nanowires and zero-dimensional (0-D) quantum dots or islands possess exotic electrical and optical properties compared to their bulk counterpart. Here, 1D nanorods draw a special attention due to their high aspect ratio for potential applications in the field of sensors and other nanoscale devices. Among various semiconductors, GaN having a direct wideband gap has stimulated a great deal of research interest due to the applications in the area of light-emitting diodes, solar cells, high-power electronics devices, laser diodes, ultraviolet photodetectors and water splitting, etc. Due to the advances in flexible or wearable optoelectronic devices, it is required to fabricate inorganic semiconductors hybrid devices directly on flexible substrates in near future. Here, we report the direct growth of various GaN nanostructures such as islands, thin films and nanorods on variety of flexible metal foils using laser-assisted molecular beam epitaxy (LMBE) technique and studied their structural and optical properties. Cubic and wurtzite mixed-phase GaN thin film and island structures have been obtained on the thin Cu and graphene/Cu metal foils under nitrogen-rich growth condition. Interestingly, the growth of high optical quality wurtzite GaN nanorods on bare and nitridated W foil is achieved at a low temperature of 600 °C. Vertically self-aligned GaN nanorods are successfully grown on flexible Ti metal foils at growth temperature of 650–700 °C by tuning the pre-nitridation condition of Ti foils. On the other hand, vertically well-oriented, high-density GaN nanorods have been achieved at 700 °C on bare Ta foil without any surface treatment. Raman spectroscopy, high-resolution X-ray diffraction and high-resolution transmission electron microscopy studies revealed the c-axis growth of high structural quality wurtzite GaN nanorods on these flexible metal foils. The photoluminescence spectroscopy measurements exhibit a near band edge emission around  ~3.4 eV with a full width at half maximum value of  ~100 meV for densely grown GaN nanorods. Our studies disclosed that various GaN nanostructures were grown directly on different flexible metal foils by tuning the surface treatment process by LMBE technique for developing futuristic flexible optoelectronics devices.
S. S. Kushvaha, M. Senthil Kumar

6. Antibacterial and Anticancer Activity of Biologically Synthesized Gold Nanoparticles

The rapid developments in the field of nanotechnology have spurred interest in many metal nanoparticles. Among many other uses, these nanoparticles are increasingly providing helpful ways to tackle-resistant bacteria. This research was aimed to identify the effect of biologically synthesized Au-NPs on bacteria Pseudomonas aeruginosa and Staphylococcus aureus and on the cancer cell lines. The antibacterial effect of Au-NPs against P. aeruginosa and S. aureus was studied by scanning electron microscopy (SEM) analysis. The bacterial culture (P. aeruginosa and S. aureus) was exposed to sublethal concentrations of Au-NPs (25 µg/mL) and incubated at 37 °C for 12 h. Antibacterial activity was observed to increase as Au-NPs increased in concentration from 25 to 100 µg/mL. The antimicrobial efficacy of Au-NPs was fairly different in Gram-positive and Gram-negative bacteria. The rigid structure of Gram-positive bacteria is likely responsible for this as it contains high peptidoglycan content that provides superior protective ability and enhances pathogenicity. To determine the effect of Au-NPs on the cell lines used in this study, the cell lines were grown in RPMI 1640 medium containing 10% fetal bovine serum and 2 mM L-glutamine. The study shows that the treatment with Au-NPs was notably effective against the proliferation of MDA-MB-231 cancer cells in a dose-dependent method. The cytotoxicity assays revealed the concentration-dependent cytotoxic effects of Au-NPs in range of 0–80 µg/ml. The results obtained confirm the strong activity of biologically synthesized Au-NPs against bacteria and cancer cell lines.
Azra Parveen, Hadeel Salih Mahdi, Ameer Azam

7. ZnCdS Thin Film: Preparation, Properties and Applications

Energy crisis is one of the serious problems around the world, but it can be normalized by renewable energy sources such as solar, wind, etc. Solar cell is a device that receives sunlight and converts it into electricity. Requirement of semiconductors in devices depends upon amplification characteristics, switching behaviour, etc. Metal chalcogenides (sulphide, selenides and tellurides) are studied in the form of thin film and is considered as heart of semiconductors due to its applications in photovoltaic cells, photoconductors, optical filters, solar cells, sensors, variety of optoelectronic devices, etc. Cadmium sulphide is a n-type semiconductor material, and it has energy bandgap 2.42 eV. Zinc is a transition element added to CdS, and its bandgap changes from 2.42 to 3.5 eV. Due to increase in bandgap, open-circuit voltage together with circuit current density of device also increases, which is attributed to greater conversion efficiency of CIGS solar cells. The preparation of ZnCdS thin films along with different Zn concentration (0.2, 0.3, 0.4, 0.5 wt%) by chemical bath deposition method has been elaborated. In this chapter, we have discussed different characteristics of ZnCdS thin films along with their synthesis process, crystal structure, energy bandgap, applications, etc.
Suresh Kumar, K. P. Tiwary

8. Nanomaterials for Pharmaceutical Applications

The field of medicine and pharmaceuticals has experienced revolutionary changes due to the development of nanotechnology. Materials or their constructions with size less than 100 nm along at least one dimension are termed as nanoparticulates. Nanoparticulates possess a greater surface area to volume ratio in comparison with bulk materials with the same composition to provide them enhanced selective therapeutic activity and are useful in the pharmaceutical field besides many other applications. Novel formulations of nanomaterials are being developed for drug encapsulation, targeted drug delivery systems (TDDs), and diagnostic purposes. Examples include polymeric nanoparticles in the form of nanospheres and nanocapsules; colloidal drug carriers such as micelles, dendrimers; phospholipid-based drug delivery systems, e.g., liposomes, phytosomes, ethosomes, etc.; solid-lipid nanoparticles (SLNs); niosomes; biphasic systems such as nanoemulsions and nanocomposite hydrogels; quantum dots; carbon nanotubes (CNTs), etc. TDDs involve direct application of drugs to the desired individual tissues with minimal damage to non-target tissues and organs resulting in the lesser requirement of drugs with enhanced biological response and protection from physical and chemical degradation. Nonmaterials not only increase the therapeutic value of drugs but also reduce their toxicological effects compared to conventional therapies. Nanomaterials, especially lipidic systems have excellent biotransformation response besides enhancing solubility and bioavailability of drugs. Nanoparticle-based dosage forms utilizing enhanced permeation and retention (EPR) effect through the biological barriers help in improving the pharmacokinetic profile and pharmacodynamic activity of the drugs. This chapter is devoted to various nanoparticulates (synthetic, semi-synthetic, and natural) having existing and potential applications in the pharmaceutical field.
Sundar Singh, S. B. Tiwari, Sanjeev Tyagi

9. PDMS on ZnO Thin Film: A Mask for ZnO Thin Film in MEMS Fabrication

Zinc oxide (ZnO) is a multifunctional material and flaunts optical, piezoelectric and semiconducting properties. ZnO thin film, as a basic layer, is used in micro-electro-mechanical systems (MEMS)-based devices for sensing and actuation purpose. ZnO-based micro-electro-mechanical structures such as cantilevers and membranes require single-side processing of Si wafer. Dry etching process (DRIE) is desired way to etch silicon. Preferably, wet chemicals like potassium hydroxide (KOH), ethylene diamine pyrochatechol (EDP) or tetramethylammonium hydroxide (TMAH) can also be used to etch silicon in a more economical way. However, ZnO film is not amicable to such chemicals and dissolves in no time. Therefore, the protection of ZnO thin film in etching solvent is a very crucial issue while releasing this kind of structures. The chapter presents silicon wet etching experiments in tetramethylammonium hydroxide (TMAH) solution using silicon-based organic polymer as a protective mask for the zinc oxide sputtered side of wafer since it is difficult to use and remove SiO2 or Si3N4 as an etching barrier, in multilayer structures. A comprehensive characterization of ZnO thin film is performed to demonstrate that structural, mechanical and electrical properties of thin film remain unaltered.
Priyanka Joshi, Jamil Akhtar

10. Photoluminescence and Chemoresistive Gas Sensing: A Comparative Study Using V2O5 Nanostructures for NH3

In this study, pristine and tin-doped vanadium pentoxide nanoparticles were synthesized via hydrothermal method and characterized using X-ray diffraction (XRD), Raman, transmission electron microscopy (TEM) and photoluminescence spectroscopy confirmed the orthorhombic structure, single phase and chain-layered structure. Microstructural analysis revealed the morphology of V2O5 as chain-layered-like structure. The crystallite size with microstrain with the peak-broadening of doped and undoped V2O5 nanoparticles was analyzed by William–Hall (W-H) method. The effect of Sn dopant on the crystallite size, morphology and luminescence property showed that the crystallite size reduces to 53.45 nm in the presence of Sn dopant. Optical sensing study on pure and Sn-doped V2O5 at room temperature showed the maximum 79.94% sensitivity for 45 ppm ammonia.
Nitu Singh, Jyoti Bamne, K. M. Mishra, Neha Singh, Fozia Z. Haque

11. Advancement in Carbon Nanotubes: Processing Techniques, Purification and Industrial Applications

Right from the starting, carbon nanotubes (CNTs) have been given special attention. Numerous researchers have investigated the processing techniques, purification as well as mechano-physical properties of this advanced form of Carbon (C). At present, CNTs and its composites have gained industrial importance due to its better mechanical, optical and thermal properties when it is compared with other materials. Development in carbon nanotubes-based composites has opened up scopes for their utilization in engineering applications. Various properties such as physical, structural, thermal and mechanical have been improved due to the utilization of CNTs as the reinforcement phase in the composites. The aim of the present chapter is to report the advancement in processing techniques, purification and industrial applications of carbon nanotubes and their composites. Among all the processing techniques, chemical vapor deposition (CVD) is widely used to synthesize carbon nanotubes and oxidation techniques is used for purification purposes. This work also examines the reported literature on the processing and purification of carbon nanotubes as well as the use of carbon nanotubes in the development of composites.
Anbesh Jamwal, Muhammed Zahid Hasan, Rajeev Agrawal, Monica Sharma, Sunil Thakur, Pallav Gupta

12. Recent Advancement in Nanostructured-Based Electrochemical Genosensors for Pathogen Detection

Pathogen detection is a critical issue to minimize the mortality caused due to different pathogenic diseases. Biosensors provide the most attractive and alternative method for the fast, selective and reliable detection of pathogens as compared to conventional methods such as PCR, ELISA and FISH which have some limitations. Biosensors in which DNA/RNA were used as recognition element are known as genosensors. Genosensors provide wide range of applications in diagnosis of diseases including infectious diseases, cancer, autoimmune diseases and much more. Recent advancement in the incorporation of nanostructures for the fabrication of genosensors had raised lot of attention. These nanostructured materials provide large surface area, biocompatibility, nontoxicity and surface defects which have led to the development of successful electrochemical genosensors. This chapter includes recent progress in the fabrication of genosensors for pathogen detection based on different nanostructures.
Summaiyya Khan, Akrema, Rizwan Arif, Shama Yasmeen, Rahisuddin

13. Nonlinear Optical Properties of Organic Dyes and Organic Dye-Polymer Nanocomposites

Organic dyes and dye-polymer nanocomposite materials have recently been viewed as a promising candidate owing to their electronic, optical and technological advancements. In this chapter, we have summarized the recent studies to examine nonlinear optical responses in organic fluorescent dyes, and dye-embedded polymer nanocomposite films. Nonlinear optical properties such as nonlinear refraction, nonlinear absorption, optical limiting under high intense pulsed and low power continuous wave lasers have also been included by employing Z-scan technique.
Sana Zafar, Mohd. Shahid Khan
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