ABSTRACT
Energy and environment are being the major challenges to the materials research community over the past few years. Photocatalysis is one of the prospective technologies to address these energy demands and environmental pollution. Photocatalysis is an effective process that can be used to convert directly solar energy into chemical energy and electrical energy. Nanomaterials as photocatalysts under suitable light irradiation have several advantages such as high surface area, stability, producing more charge carriers, and suitable optoelectronic properties for photocatalytic applications. Pristine nanomaterials are limited in practical application due to cost efficiency, lack of recovery from the reaction mixture, reusability, and the short lifetime of charge carriers. Recently, magnetic semiconducting nanoparticles are getting more attention in photocatalysis due to their better efficiency in UV and visible light, magnetically recoverable, and reusable. Photocatalytic performance of magnetic nanomaterials is constrained by high rate of charge recombination, surface area, and stability. This can be overcome by functionalization of the magnetic nanomaterials by covalent and noncovalent functionalization, surface modification, formation of nanocomposites with metal oxides, 2D materials, and so on. On the other hand, in conventional synthesis routes, harmful reducing agent, capping agent, and surfactants are used to control the various parameters of the synthesis process, which can also cause an environmental imbalance in the ecosystem. The green synthesis method is one of the alternative, cost-effective, biocompatible, and nontoxic methods for preparing of nanoparticles with plant extracts. In green synthesis process, plant’s (seed, fruit, leaf, peel, etc.) extract is used as a reducing, capping, and stabilizing agent to control the size and the morphology of the nanomaterials. Hence, this chapter mainly focuses on various green synthesis methods of magnetic nanomaterials such as chemical reduction, sol-gel, hydrothermal, combustion, and microwave-assisted and biosynthesis methods. Also, various methods for functionalization of magnetic materials (by forming metal nanocomposite, metal oxide nanocomposite, and carbon-based nanocomposite) and their photocatalytic applications have been summarized.
