Synthesis and Applications of Nanomaterials and Nanocomposites

Metal halide perovskites are gaining attention for their interesting optoelectronic properties which result in their promising use for commercial applications. The ease in the fabrication and processability of perovskite nanocrystals with high photoluminescence quantum yield has tremendously attracted the research community and since then various approaches for their synthesis have been developed. This chapter focuses on various size and shape-controlled solution-based synthesis methods for perovskite nanocrystals. Furthermore, synthesis of defect-free perovskite nanocrystals to attain long-term stability along with high efficiency is the primary focus of the growing research community. Therefore, deeper insight into defect properties in perovskite nanocrystals is crucial despite of their defect-tolerant nature. Thus, the purpose of this chapter is twofold (i) to give a complete understanding of various facile synthesis strategies for metal halide perovskite nanocrystals while discussing their advantages and limitations and (ii) to facilitate an in-depth insight about the formation of native defects both from the experimental and theoretical perspectives.

Graphene has been a material of interest, especially since the discovery of its free-standing form in 2003. The discovery provided hope to researchers looking for breakthroughs in the field that had not seen significant growth for long. Incremental improvements are not enough to meet the exponentially growing demands for cheap, convenient, and high-performing technologies. Graphene has the potential to provide new ways of achieving goals that previously seemed impossible by redefining the frontiers of science. It is because of the unprecedented material properties of graphene that were never demonstrated before by any other material. Novel and better material properties open up doors to new technologies and advancements in existing ones. However, it is imperative to obtain the material of suitable quality at a reasonable cost for it to compete with prevailing alternatives. In this chapter, various methods for synthesizing graphene have been discussed with a particular focus on the liquid-phase exfoliation (LPE) of graphite. Characterization with Raman spectroscopy, electron diffraction, and microscopy-based tools have been explored. The chapter also reviews applications of graphene in a few emerging areas. Graphene-based composites, with emphasis on their syntheses and applications, will be discussed.

Because of the unique features of a derivative of allotropic carbon graphite that has been known as graphene oxide, a number of unique optical, electrical and thermal breakthroughs has come into limelight. This has made graphene oxide as the material having the most intriguing nature which is still under investigation. Furthermore, apart from just a precursor for the manufacturing of graphene, researchers have discovered a plethora of unique optical, electrical, and chemical characteristics of graphene oxide that may be used in a variety of applications. The synthesis of GO, its structure and characterisation along with its functionalization and GO applications are the subject of this chapter. Additionally, we have discussed the use of GO in environmental, medicinal, and biological applications, freestanding membranes, and diverse composite systems. The synthesis of graphene oxide and its nanocomposite based on novel nanoparticles will be covered in this chapter. A brief overview has also been provided, with a focus on the use of graphene oxide and its nanocomposite in various fields, particularly waste water treatment of water.

Nanorods (NRs) have been a subject of profound interest because of a wide variation in their electronic properties with confinement. In this article, a single-step, self-stabilizing, two-electrode electrochemical synthesis method is demonstrated for growing metal–oxide and metal-hydroxide NRs at room temperature. Barium hydroxide NRs were fabricated using a simple electrochemical reduction of Ba²⁺ ions from a barium chloride precursor solution without using any capping agent. The synthesized NRs were characterized using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Optical Microscopy (OM), Energy Dispersive X-Ray Spectroscopy (EDS), Selected Area Electron Diffraction (SAED), and UV–Vis. absorption spectroscopy. Effects of temperature and potential differences across the electrodes on the shape and size of the synthesized NRs were also investigated. NRs of diameters in the range of 80 to 300 nm were fabricated with different growth parameters. Furthermore, the synthesis of silver oxide NRs at room temperature is also demonstrated with the method.

Recent studies show that ionic liquids and high concentration salt solutions are promising alternatives to conventional electrolytes for high-performance batteries. The intercalation of electrolytes in nanoscale electrode confinements is a vital phenomenon governing the performance of batteries. A fundamental understanding of the electrolyte structure and stability inside electrode confinements helps explore the full potential of modern electrolytes for electrochemical devices. Factors such as the confinement shape, size, and flexibility govern the stability of electrolytes in nanoscale confinements. Enhanced molecular dynamics simulation can help delineate the free energy underlying the process of electrolyte evaporation or deintercalation from confinements. However, such studies in this direction are limited to few electrolytes only. This chapter highlights recent computational studies carried out in our group exploring the stability and structure of ionic liquids and water-in-salt electrolytes in nanoscale confinements, and provides a plausible mechanism for their intercalation and deintercalation behaviour.

Coinage metal nanoparticles including gold, silver, and copper are absorbed due to their size and shape-dependent distinct optoelectronic and chemical properties, in addition to their effective use in health-related applications. Among these nanoparticles, Because of their ease of fabrication, characterization, as well as surface modification, Au NPs have triggered a lot of interest in crucial biological applications. Coinage metal nanoparticles provide a robust platform for solving health-related problems because of their outstanding physical and chemical properties. Stable and biocompatible coinage metals NPs have been employed with targeted drug delivery and killing cancerous cells, diagnosing several types of cancers pharmacological applications, i.e., sensing probes, therapeutic agents, and drug delivery systems.

Nanotechnology comprehends the study of various attributes of nanostructured materials at the molecular and sub-molecular levels. Nanoparticles (NPs) have garnered attention recently as a potential tool for targeted therapy in the clinical setting. Distinct benefits of nanotechnology-based drug-delivery systems to overcome the pharmacokinetic limitations of conventional treatments are due to their small size and thus promise a good course of action in all aspects of life. Small biological targets such as RNA, DNA and proteins can be easily manipulated by nano drug delivery vehicles. The ultimate goal of research interest in nanotechnology is to create therapeutically relevant nanoparticles (NPs) with suitable dimensions, chemical composition, and surface properties that can encapsulate the appropriate dosage of a targeted drug or molecule with improved kinetics and dynamics in a biological system. To increase safety and effectiveness, NPs facilitate transport across membranes, enhance the stability and solubility of encapsulated cargos, and improve circulation time. Inorganic NPs are used in various drug delivery and imaging applications and are manufactured to have different sizes, topologies and geometries. These factors have led to substantial NPs research that has produced positive outcomes, with inorganic NPs serving as the main focus for the delivery of the drug.

Bio-nanocomposites are next generation food packaging materials that promote better food quality. Bio-nanocomposites are the replacement for current non-biodegradable and non-renewable materials which are applied as food packaging materials. These nanocomposites are promising materials for human health, food storage and eco-system. Advantages of incorporating nanomaterials into the packaging materials include better physico-chemical, mechanical, antibacterial and antimicrobial properties. Several kinds of nanomaterials including metal, metal oxide and other inorganic and organic nanostructures have proven to be effective to increase the shelf life and reduce the spoilage of food by different mechanism of action. Incorporation of nanomaterials in biopolymer makes the production and application of food packaging material.

Silver and copper nanowires have been used in many areas, like sensors, catalysis, optoelectronics, etc. They are well-known by the excellent optoelectronic and chemical properties. Here in this chapter, some interesting aspects of these metal nanowires are reviewed, including: (i) the synthesis methods of the metal nanowires; (ii) application of these nanowires in transparent conductors; (iii) application of the transparent conductors in flexible optoelectronic devices, like solar cells, OLEDs, touch screens, transparent heaters, and so on. Besides the applications, this chapter also sheds light to some fundamental problems, including the coarsening dynamics of nanowires, corrosion and protection of nanowires, and also the conducting mechanism of the transparent conductors basing on nanowires. Finally, perspective is given.

Quantum Dots (QDs) are zero-dimensional nano-particles portraying their distinguishing optical and electronic properties, they are used as nano-sensors. QDs have improved fluorescence characteristics, which comprise photostability, broad excitation spectrum, and narrow emission spectrum. QDs deal with the extensive and sensitive sensing of heavy metal ions ascribed to the presence of distinct capping agents and various functional groups lying outwardly of the QDs. These capping strata and functional moieties attune to the sensing capacity of the QDs, which influences the interactions of QDs with different analytes by various mechanisms. In this chapter, a brief overview of heavy metals as environmental contaminants, their impact on human health, and conventional techniques of detection and underlying modes are first introduced. Then, the role of QDs in sensing heavy metals such as mercury, cadmium, lead, arsenic, chromium, etc., and their progress in the multiplexed determination of heavy metal ions are explored.

Clean non fossil sources of energy have an increasing urgency to support industrial and population growth to achieve this goal, the continuous development of nanostructures and nanomaterials for different applications such as photocatalytic water splitting is under intense investigation. Two of the most important materials namely, titanium dioxide, TiO₂, and ferrites having the MFe₂O₄ structure where M is transition metal are introduced in this chapter. Ferrites and titanium dioxide are two interesting nanostructures having great potential. Ferrites have many members in the family hence, offering diversity in structural and physical properties which in turn give chance for a large variety of purposes and applications. They own an energy band gap that is small enough to crop photons from the visible light region. They are also abundant on earth and have important physical properties like magnetism and multiferroicity in addition to being biocompatible which will increase their usability. On the other hand, TiO₂ has several advantages, including its stability in terms of chemical and thermal properties, in addition to its availability, photoactivity, and relatively elevated charge transfer ability. Furthermore, the nontoxicity, high oxidative strength, and cheap price are additional advantages. Despite the large band gap and its related UV-light activation, TiO₂ is one of the highly studied photocatalysts. Moreover, it has been extensively investigated in many aspects, including the kind of the oxidative species (·OH radicals vs. h+), the location of the photoinduced reactions (at the surface or in the bulk), and the ways that enhance the photocatalytic performance.. Many of the synthesis techniques for both, ferrites and TiO₂ were adopted to serve definite purposes like control over phase purity, morphology, size, and dispersion which are discussed in this chapter.

With the depletion of traditional fossil fuels, rising pollution levels and fast growth of the global economy. New technology for energy conversion and storage, as well as efficient, sustainable energy sources, are all urgently needed. The development of supercapacitors (SCs) as an energy storage device has received a lot of interest in recent years. SCs are comparable to dielectric capacitors in terms of their high-power density, cyclic stability, and discharge rate. In addition, a high energy density that is comparable to batteries. In this chapter, polyaniline (PANI) based materials for electrochemical supercapacitor (ESs) electrodes are thoroughly reviewed. Pure PANI electrodes have low cycle life, low power density, and poor mechanical stability resulting from the swelling and shrinkage during the charging and discharging processes. Nevertheless, the development of nanocomposite of PANI with carbon materials or metal compounds could overcome the drawbacks of pure PANI and achieve higher electrochemical performance. Capacitance, energy, power, cycle performance, and rate capability have all been used to evaluate the performance of nanocomposites.

CeO₂ has been an important functional material due to its unique oxygen storage capacity and ability to form Ce³⁺/Ce⁴⁺ redox system. The abilities of CeO₂ can be further modified by forming composites with noble metals and metal oxides, which can lead to the design of unique catalysts for different catalytic processes. Hereby, the use of CeO₂ based composites in the important gas phase, liquid phase and photocatalytic reactions, namely—water–gas shifting, oxidation of alcohol, water splitting, photocatalytic degradation of organic pollutants, Suzuki–Miyaura coupling etc. have been discussed.