Fabrication Strategies for Nanomaterials: Top-down, Bottom-up an Hybrid Approaches

Nanomaterials, characterized by their unique properties at the nanoscale, have garnered significant attention in recent years for their diverse range of applications across various fields (Barhoum et al., 2022; El-Khawaga et al. 2023). These materials exhibit distinct physical, chemical, and biological properties compared to their bulk counterparts, owing to their high surface area-to-volume ratio and quantum confinement effects (El-Kady et al., 2023). The nanomaterials are categorized into four main types, i.e., zero-dimensional (0-D), one-dimensional (1-D), two-dimensional (2-D), and three-dimensional structures (3-D), according to their size and shape as shown in Figure 1. Zero dimensional contains spherical shapes and one-dimensional includes nanowires, nanotubes, nanorods, and nanofibers. Two-dimensional structures consist of thin films and sheets layered one by one. Three-dimensional structures are arrays of nanotubes, nanocubes, nanowires, etc. (Vaseghi & Nematollahzadeh, 2020). Nanomaterials are also classified based on the materials used for the synthesis. This classification typically includes carbon-based nanomaterials, inorganic-based nanomaterials, organic-based nanomaterials, composite based nanomaterials, and plant-based nanomaterials (Figure 2) (Singh et al., 2020).