**Abstract**

Nanoparticles are small particles that range from 1 to 100 nm in size, exhibit several physical and chemical features. An understanding of nanoparticles would reveal great qualities and potential applications that would aid the diversification of thin film technologies. The synthesis methods employed like top-down, bottom-up, chemical, biological, and mechanical processes have great influence on the properties exhibited by such nanomaterials. This review covers an insight into the knowledge of nanoparticles, their classifications, parameters affecting their efficient performance, synthesis and characterization techniques of nanoparticles. Nanoparticles are also characterized to obtain their morphological, structural, optical, elemental, size, and physiochemical features. The potential applications of nanoparticles have not been left undiscussed.

**Keywords:** nanoparticles, thin film technologies, synthesis, characterizations, applications

## **1. Introduction**

Nanotechnology involves synthesizing and developing different nanomaterials. The field of nanotechnology allows different nanoparticles of unique features to be produced. Nanoparticles (NPs) are complex material particles that fall within the range of one to hundred nanometers. Their nanometer sizes drive the chemical, optical, physical, and electric features of the nanoparticles [1]. Naturally, nanoparticles can be sourced from geological, biological, meteorological, and cosmological means. However, nanoparticles can be created from liquid and solid materials by breaking down biopolymers, condensing gases, wet chemical process, implantation of ions, hydrothermal process, pyrolysis, radiolysis etc. Nanoparticles are usually viewed with the aid of electron microscopes, can penetrate filters, and have unique mechanical properties that distinguish them from the bulk materials. Nanoparticles exist in various shapes like nanorods, nanostars, nanofibers, nanospheres, nanoflowers, nanoboxes etc. [2].

Nanoparticles comprise a functionalized surface, a shell of different layered materials, and the core/main nanoparticle [3]. The features of materials in their bulk form are different from their nanoparticle forms because of the large area to volume ratio, interfacial layer, affinity to solvents, kind of coating, quantum mechanics effects, rate of diffusion, mechanical, and ferromagnetic features [1]. The large area to volume ratio makes the nanoparticles highly reactive and able to penetrate membranes. The chemical nature of nanoparticles should be studied to enhance their molecular attachment to surfaces.
