The fast-rising market for portable electronic devices and the development of hybrid electric vehicles require the use of clean energy sources at a much higher level than presently in use. Nanomaterials have the potential to revolutionize energy harvesting and storage, providing a sustainable solution for our ever-growing energy needs. These materials combine the unique properties of different nanomaterials, leading to the development of new hybrid nanomaterials, to create synergistic effects, enhancing their overall performance and efficiency. Owing to their tunability and versatility, scientists can tailor the composition, morphology, and structure of these materials to optimize their performance. This technology has led to the development of advanced supercapacitors, fuel cells, solar cells, supercapacitors, rechargeable batteries, etc. with high energy density, fast charging capabilities, and long cycle life. This chapter is focused on specially designed hybrid nanomaterials for energy harvesting and storage applications.
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Burning fossil fuels is widely recognized as the leading contributor to climate change, resulting in significant impacts on terrestrial and aquatic ecosystems and posing health risks for both humans and the environment (Crutzen et. al., 2008b). A promising method to resolve this challenge is to replace fossil fuel energy resources with alternative options that are environmental friendly, readily available, cost-effective, and environmentally sustainable. Renewable energy sources, such as solar energy harvesting and storage, are becoming more crucial in order to meet energy challenges (Lee et. al., 2018b). Scientists are developing materials that can effectively harness solar energy. Solar cells should be made with materials that have the proper band gap to get the most out of the sun's energy, have good charge transport, are highly stable, have low manufacturing costs, and of course, be eco-friendly.
In the current times, the use of bulk materials is not sufficient to meet the growing energy demand. As a result, various nano-structured materials have been explored. However, their inherent properties (less conductance, poor mechanical strength, and side reactions due to unprotected surfaces) make them unsuitable for meeting the requirements (Liu et. al., 2010; Kang & Ceder, 2009; Fu et. al., 2006). To overcome the shortcomings of single-phase nano-materials, various hybrid nano-structures have been proposed (Wang et. al., 2008; Ran & Lee, 2008; Zhang et. al., 2008; Zhang et. al., 2009; Ran et. al., 2010). Hybrid nanomaterials (HNMs) are promising candidates for energy harvesting and storage applications due to their unique functionalities at the nanoscale. These materials integrate different components, such as nanomaterials, polymers, and organic molecules, to achieve enhanced performance and address the limitations of conventional energy storage systems. They offer several benefits which include high surface area, tunable properties, and synergistic effects that enhance overall performance. The high surface area provides more sites for electrochemical reactions to occur which results in better energy storage efficiency. Tailoring the properties of HNMs by tuning the composition, structure, and morphology of its constituents allows the designing of materials with desirable properties, such as conductivity, stability, and ion transport, required for different energy storage applications. The combination of a conductive material with a high-capacity material can improve both conductivity and energy storage capacity.
Over the past several decades, various energy harvesting technologies have undergone a great deal of research for their practical applications. Piezo (Xu et. al., 2010; Wu et. al., 2014) and triboelectricity (Zhu et. al., 2014; Jing et. al., 2015) are used to capture mechanical energy, pyroelectric (Morozovska et. al., 2010; Yang et. al., 2012), and thermoelectric (Poudel et. al., 2008), (Kim et. al., 2015) effects are used to capture heat, and photovoltaics (You et. al., 2013) are used to capture solar energy. All of these technologies are designed to turn energy from the environment into electricity.
Energy storage devices are important for powering electronic devices/systems. They enable us to use energy to drive them, and so the integration of energy harvesting and storage devices is the ultimate goal in terms of technology development. This is a relatively new area of energy research that focuses on the use of nanomaterials and nano-technologies to capture energy to drive micro-/nanoelectronic systems. It can be used as a substitute for batteries or to extend their life.