Biochar-Based Nanocomposite Materials: Types, Characteristics, Physical Activation, and Diverse Application Scenarios

Biochar activation has been used to augment the physicochemical properties, such as an increase in specific surface area, porosity, and surface functional groups, while improving efficiency for different applications. The physical activation method has generally driven the activation and modification of biochar. The physical activation method involved simply heating the feedstock to a higher temperature in the presence of activating agents such as CO2, inert atmosphere, steam, or pyrolysis gases that caused the loss of gases and volatile components of the feedstock and formed a porous matrix with enhanced specific surface area. Physical activation has been predominantly controlled by different parameters such as temperature, duration of heating, degree of activation, quality of precursors, and activating agent. Biochar-based nanocomposites have been considered advanced materials and exhibit distinctive properties with enhanced pore size, functional groups, surface-active sites, etc. Generally, it has been distinguished based on the nanomaterial, viz., oxide/hydroxide biochar, magnetic biochar, and functional nanoparticles-coated biochar. The chapter has deliberated mechano-chemical strategies such as steam activation, microwave, magnetic modifications, ball milling, and heat treatment methods for fabricating biochar-based nanocomposites with improved properties. It has promised different applications in agro-environment arena with several other applications (such as energy, catalysis, and biomedical). Also, the pros and cons of the different techniques have been explored for future applications.