Applications of Nanomaterials in Energy Storage and Electronics

Carbon nanotubes (CNTs) and their nanocomposites are used in various products and technologies due to their unique characteristics. For their future implementation, the manufacturing of CNTs with appropriate specifications has gained momentum in the area of nanoscience and technology. Conventional phase change materials used in solar thermal energy storage have low thermal conductivity. CNTs are used to prepare phase change materials with high thermal conductivity to solve this issue. This chapter addresses the synthesis, structure, and properties of CNTs. The different varieties of solar energy storage systems used to store solar radiation are also discussed. Further, we explain the phase change materials (PCMs) as suitable solar thermal energy storage systems and discuss the methods to prepare CNT-based nanomaterials for use as a heat transfer fluid (HTF) after using the CNTs based PCMs in solar storage systems. CNT based nanomaterials as a heat transfer fluid significantly increase the effective receiving efficiency, thermal conductivity, and absorption coefficient of such storage systems. 

Carbon-based nanostructured materials have derived substantial attention as novel functional materials towards the fabrication of various biosensing platforms owing to their interesting physicochemical and optoelectronic properties, as well as desired surface functionalities. These nanomaterials provide increased and oriented immobilization of biomolecules along with maintaining their biological activity in view of their lower cytotoxicity and higher biocompatibility. The integration of carbon nanomaterials with biosensing platforms has provided new opportunities and paved the way for the efficient detection of various biomolecules and analytes. These nanostructured materials-based biosensors have improved biosensing characteristics, including broader linear detection range, lower detection limit, better selectivity, and higher sensitivity. This chapter summarizes the results of different electrochemical and fluorescent biosensors related to various nanostructured carbon materials, namely carbon nanotubes (CNTs), graphene and its derivatives (reduced graphene oxide (rGO), graphene oxide (GO), graphene quantum dots (GQDs) and carbon dots (CDs). 

Carbon nano-onions (CNOs) or multilayered fullerenes have received considerable attention in diversified research areas such as supercapacitors, fuel cells, batteries, photovoltaics, and biosensors due to their unique physicochemical, optical, catalytic, and electronic properties. These structures were first observed in 1992, and ever since, a considerable amount of research on their physical properties and development of CNOs based supercapacitors and sensors has been successfully witnessed. CNOs are prepared via different experimental techniques, and their structural and physical properties often rely upon the fabrication process or parameters. This chapter presents an overview of different methods that have been adapted to prepare CNOs and their novel properties with a focus on the fundamental curvature morphology effects. A comprehensive discussion on the potential applications, citing recent research, is provided. The challenges and the potential directions of CNOs-based materials with an eye to develop highly efficient and long-term stable CNOs-based energy storage devices and sensors are also addressed.

Over the last few years, due to its exceptional two-dimensional (2D) structure, graphene has played a key role in developing conductive transparent devices and acquired significant attention from scientists to get placed as a boon material in the energy industry. Graphene-based materials have played several roles, including interfacial buffer layers, electron/hole transport material, and transparent electrodes in photovoltaic devices. Apart from charge extraction and electron transportation, graphene protects the photovoltaic devices from atmospheric degradation through its 2D network and offers long-term air or environmental stability. This chapter focuses on the recent advancements in graphene and its nanocomposites-based solar cell devices, including dye-sensitized solar cells (DSSCs), organic solar cells (OSCs), and perovskite solar cells (PSCs). We further discuss the impact of incorporating graphenebased materials on the power conversion efficiency for each type of solar cell. The last section of this chapter highlights the potential challenges and future research scope of graphene-based nanocomposites for solar cell applications.

Graphene has gained recognition within the research community owing to its fascinating properties in the plethora of energy-related applications. The properties include high thermal and electrical conductivity, greater mechanical strength, optical translucency, intrinsic flexibility, massive surface area, and distinctive two-dimensional structure. Graphene is highly competent in enriching the functional performance, endurance, stability of many applications. However, still ample research diversity will be desirable for graphene commercialization in energy sectors. This intuitive scrutinization reconnoitered the talented employment arena of graphene in various energy storage and harvesting fields. The amplification of the versatile applicability of graphene and comprehensive perception regarding pros and cons of graphene based nanohybrids could critically pinpoint current constrictions by upgrading its characteristics performance. The chapter provides an insight into the unique features of graphene and amalgamation with nanomaterials to enlighten its various energy-related applications, including supercapacitors, biosensors, solar cells, batteries. With the breakneck miniaturization in the employment of graphene in various energy-relevant applications, it is crucial to epitomize align="center" and figure out the progressive momentum of graphene and its nanohybrids in several energy-related application territories. 

In recent years, the development of industrialization and the increasing population has increased energy consumption across the globe. So, there is a need for green and sustainable energy generation from solar cells with greater efficiency. Photovoltaic (PV) technology with improved performance is going to be a gamechanger in resolving the energy crisis in an eco-friendly and more sustainable manner. Widely used silicon (Si) based PVs are relatively expensive due to strong requirements for the high purity of crystalline semiconductors. The Si wafer cost covers 50% of the total cost of the align="center"module. In this regard, metal oxidebased semiconductors are stable and environment-friendly materials that are used in photovoltaics as photoelectrodes in dye solar cells (DSCs), quantum dot sensitized solar cells, and build metal oxide p–n junctions. This chapter comprehensively discusses the most recent progress in metal oxide semiconductors in alternative type solar cells, in particular dye-sensitized solar cells (DSSC). 

The conservation of energy and the materials utilized for its storage have gathered a wide range of interest nowadays. Two-dimensional hexagonal boron nitride (2D h-BN), often termed as ‘white graphene’, exhibits various interesting properties and hence, acts as a promising future candidate for energy sustainment and storage. This material assures exquisite thermal and chemical stability, high chemical inertness, exotic mechanical strength, and good optoelectrical properties. 2D h-BN undergoes physical and chemical modulations, and their properties could be tuned, making them more appropriate for energy storage applications. They could also be incorporated with other 2D materials like graphene, molybdenum disulphide (MoS2), etc., to improve their properties. It is thus thoroughly and systematically studied for its further usage in field effect transistors (FETs), UV detecting devices and emitters, photoelectric and microelectronic devices, tunnelling devices, etc. The comprehensive overview provides an insight into 2D h-BN and its synthesis routes developed within the past years. The different major properties exhibited by 2D h-BN are also reviewed. Hybridization and doping processes are also discussed. Functionalised h-BN and its utilisation in different energy storage applications are elaborated and reviewed. This review chapter will give a quick glance and perspectives on 2D h-BN and its extraordinary characteristic features that could enhance their usage in energy conversion, storage, and utilisation applications. 

This book chapter elucidates the recent works accomplished in the platform of flexible/wearable supercapacitor devices based on metal-organic frameworks (MOFs) electrodes. Comprehensive insight into various types of supercapacitors, the advantage of MOF-based flexible supercapacitors among them, classifications of MOF-based flexible supercapacitors concerning their building blocks, and recent research accomplished with their pros and cons are illustrated. Finally, the performance assessment, strategies to improve efficiency, and future perspectives are briefed.

Compositional designed electrodes exhibiting high specific capacities are of great interest towards align="center"high performance charge storage devices. Electrode surface can store charge or guest ions due to structural confinement effect. Ion storage capacity depends on the structural integrity of electrode (anode) materials of batteries. Electrolyte selection also decides the storage capacity of batteries and other charge storage devices. Volume expansion or variation can be minimized through structural variation of the electrode. align="center"The charging phenomenon proceeds through the continuous ion destruction process of adsorbed ions into semipermeable align="center"pores. Dimension controlled electrode materials possess superior ion storage capacity. The contemporary design is an effective way to improve the charge storage capacity of electrodes. Low dimension materials exhibit better charge storage capacity due to high surface density (surface to volume ratio) and efficient charge confinement. The confined dimensions (quantum confinement) play important roles in orienting the desired kinetic properties of nanomaterials, such as charge transport and diffusion. This chapter emphasizes critical overviews of the state-of-the-art nanowiresbased align="center"electrodes for energy storage devices, such as lithium-ion batteries, lithium-ion capacitors, sodium-ion batteries, and supercapacitors. Ions or charges can be percolated easily through nanowire networks due to fast adsorption and diffusion. High-rate capability is intensified align="center"over large electroactive surface in align="center"an ordered nanowire electrode. 

Polymer nanocomposite is a new kind of material that offers to substitute traditionally filled polymers. The nanomaterial polymer matrix inter-phase area increases drastically due to the inherent high surface-to-volume ratio resulting in remarkably enhanced properties compared to the pristine polymers or their conventional counterpart filled nanocomposites. Nanocomposites have several novel properties such as nonlinear optical properties, electronic conductivity and luminescence. Therefore, their use has been projected in many areas like chemical sensors, polymer electrolyte membrane fuel cell (PEMFCs), electroluminescent devices, batteries, electrocatalysis, smart windows and memory devices. PEMFCs embody a potential candidate for electrochemical energy generation in the twenty-first century due to their better efficiency and environmentally friendly nature. Proton exchange/Polymer electrolyte membrane (PEM) plays a vital role in the PEMFCs. Currently, PEM like Nafion and Flemions are widely used in PEMFC, which have certain drawbacks such as fuel cross-over through the membrane, low operating temperature, and high cost. The researchers from several laboratories across the globe have put their extreme effort into preparing a novel polymer electrolyte membrane with high proton conductivity, better long-term stability, improved thermal stability, high peak power density (PPD), and less fuel crossover with minimum cost. The advent of nanotechnology has brought a new scope to this research area. The hybrid (organic polymer with inorganic nanoparticle) nanocomposite membrane has developed into an exciting alternative to the conventional polymer membrane applications. It provides an exclusive blend of inorganic and organic properties and helps to overcome the drawbacks of align="center"pristine polymer membranes. In this book chapter, we have focused on different nanomaterials and their effect is analyzed in polymer electrolyte nanocomposite membranes for PEMFC applications. 

Graphene, the most exciting carbon allotrope, and its derivatives such as graphene oxide and graphene quantum dots have sparked a flurry of research and innovation owing to their unprecedented optoelectronic properties. Graphene and its nanocomposites have been widely used in a variety of opto-electronic devices such as photodetectors, transistors, actuators, biomedical aids, and membranes. Their sp2 hybridization state provides some extraordinary opto-electronic and mechanical properties. Chemical exfoliation of graphite into graphene and graphene oxide allows us to mix graphene nanocomposites into various layers of organic solar cells and other organic semiconductor-based optoelectronic devices, especially for roll-to-roll fabrication of large-area devices at a lower cost. Recently, these nanocomposites have also been utilized as charge transport layers and surface modifiers in perovskite solar cells and perovskite light-emitting diodes. Researchers have found that the presence of graphene, even at very low loading, can significantly improve the device's performance. In this chapter, we have discussed the application of graphene oxide, reduced graphene oxide, and doped graphene oxide in various combinations in perovskite solar cells and perovskite light-emitting diodes; these nanomaterials can be utilized either in transport layers of a multilayered device or directly incorporated in the active layers of these optoelectronic devices. These nanocomposites generally improve the device efficiencies by improving the band alignment at heterojunctions in a multilayered device by substantially reducing the trap states and the charge transfer resistance. These nanocomposites are found to achieve significantly improved device power conversion efficiency and stability of perovskite-based optoelectronic devices.

The dispersion of nanomaterials in ferroelectric liquid crystals (FLC) has turned out to be a promising method for fabricating optical memory devices and tuneable electro-optical materials. In a nanosuspension between FLC and nanoparticles, the presence of the dopant particles creates a synergic interaction with host FLC, which leads to the improvement of electro-optical properties. Tailoring with nanoparticles of suitable size, concentration, and compatibility results in various fascinating effects and new multifaceted composites for electro-optical devices. Adding nano-sized materials such as metallic, semiconducting, insulating or other functional species into the FLC matrix is a fertile method, giving rise to or increases in memory retention and other electro-optical properties that can replace the current electro-optical devices. These advancements depend on the harmony between the guest and host materials. This chapter gives a comprehensive overview of the present technologies and enhancements that have been acquired in nanoparticle/FLC composite systems, especially for optical memory devices and display applications.

Among the variety of nanostructures that have been explored as a favorable material for the application of higher energy storage devices as supercapacitors, catalysts in high-performance batteries, proton exchange membranes in fuel cells, optoelectronic devices, and so on, 2D & 3D nanostructure of graphene-based derivatives, metal oxides and dichalcogenides have received the most potential attention for building high-performance nano-devices due to their extraordinary properties. Over the past decade, several efforts have been implemented to design, develop, and evaluate electrodes' structures for enhanced energy storage devices. A significant modification has achieved the remarkable performance of these synthesized devices in terms of energy storage capacity, conversion efficiency, and the reliability of the devices to meet practical applications' demands. Light-emitting diode (LED) in quantum well or quantum dots is considered an important aspect for an enhanced optoelectronic device. This current study outlines different 3D nanostructures for nextgeneration energy storage devices. It provides a systematic summary of the advantages of 3D nanostructures in perspective to next-generation energy storage devices, photocatalytic devices, solar cells, a counter electrode for metal-ion batteries, and supercapacitors, optoelectronic nano-devices.

Nanomaterials are materials with cross-sectional dimensions varying from one to hundreds of nanometers and lengths ranging from hundreds of nanometers to millimeters. Nanomaterials either occur naturally or can be produced purposefully by performing a specialized function. Until recently, most nanomaterials have been made from carbon (carbon nanotubes), transition metals, and metal oxides such as titanium dioxide and zinc oxide. In a few cases, nanoparticles may exist in the form of nanocrystals comprising a number of compounds, including but not limited to silicon and metals. The discovery of nanomaterials has played a vital role in the emerging field of research and technology. Recently, a large amount of research efforts has been dedicated to developing nanomaterials and their applications, ranging from space to electronics applications. In this chapter, we describe the role of nanoparticles in electronics and energy storage applications, with examples including chips, displays, enhanced batteries, and thermoelectric, gas sensing, lead-free soldering, humidity sensing, and super capacitor devices. The chapter also attempts to provide an exhaustive description of the developed advanced nanomaterials and different conventional and advanced techniques adopted by researchers to synthesize the nanoparticles via bottom-up techniques (pyrolysis, chemical vapor deposition, sol-gel, and biosynthesis) and top-bottom approaches (mechanical milling, nanolithography, laser ablation, and thermal decomposition). 

 The development of extremely flexible photovoltaic (PV) devices for energy harvesting and storage applications is currently receiving more attention by the researchers from industries. The presently available energy storage devices are too rigid and extensive and also not suitable for next-generation flexible electronics such as silicon-based solar cells. Thus, the researchers have developed high-performance, lightweight, conformable, bendable, thin, and flexible dependable devices. On the other hand, these energy storage devices require to be functional under different mechanical deformations, for example, bending, twisting, and even stretching. The nanomaterial (TiO2, ZnO, Ag, etc.) coated fabrics also play a vital role in improving the efficiency of the solar cell (devices) to a great extent. The current chapter provides information about the development of nanomaterials-based flexible photovoltaic solar cell devices for wearable textile industry applications. The fabricated carbon ink printed fabrics such as polyester, cotton woven and nonwoven, and polyethylene terephthalate nonwoven can be used as cathode and heating sources of PV devices. The organic and flexible conductive substrate printed with carbon ink can be utilized as heating source fabrics for wearable electronics devices. The flexible substrate-based photovoltaics (PV) device is mostly used in the textile industries due to its flexibility, environmental friendliness, low cost as well as easy processability. The flexible-wearable photovoltaic devices pave the way to be used for enormous applications in various fields.