Basics and types of Nanomaterials

What is a nanoparticle?

Those particles that have size ranges between $1$ to $100 \: nanometres$ are called a nanoparticle. The particles are undetectable by the human eye. There are significant differences in the properties (like magnetic, electrical, Structural, Mechanical, and optical properties) of nanoparticles and bulk materials.

What is nanomaterial?

Those materials that have at least one dimension should be in nanometres i.e. $10^{-9}m$ are called nanomaterials. The prefix 'nano' means a billionth $(10^{-9})$.

Types of nanomaterials

There are two types of nanomaterial that can be classified:

A.) On the basis of dimension

B.) On the basis of material

A.) On the basis of dimensions: According to Siegel, nanostructured materials are classified on the basis of dimension:

1.) Three-dimensional nanomaterials (Bulk Nanomaterial)

2.) Two-dimensional nanomaterials (Quantum Well)

3.) One-dimensional nanomaterials (Quantum Wire)

4.) Zero-dimensional nanomaterials (Quantum Dot)

1.) Three-dimensional nanomaterials (Bulk Nanomaterial): These nanomaterials have not confined to the nanoscale range in any dimension. These materials have three arbitrary dimensions above the nanoscale i.e. $100 nm$. The bulk three-dimensional nanomaterials are composed of a multiple arrangement of nano-size crystals in different orientations. The three-dimensional nanomaterials or bulk nanomaterials can be used as bundles of nanowires, dispersion of nanoparticles, and nanotubes as well as multi-nano layers (polycrystals) in which the $0D$, $1D$, and $2D$ structural elements are in very close contact with each other and form interfaces.

2.) Two-dimensional nanomaterials (Quantum Well): These nanomaterials have one dimension in the nanoscale. It is also called a quantum well. This means that the particles of material are confined only along one dimension. The 2D nanomaterials exhibit plate-like shapes. It includes nanofilms, nanolayers, and nanocoatings with nanometre thickness.

3.) One-dimensional nanomaterials (Quantum Wire): These nanomaterials have two dimensions in the nanoscale. It is also called quantum wire. This means that the particles of material are confined in two dimensions. This leads to needle-shaped nanomaterials. It includes nanofibers, nanotubes, Nanorods, and nanowires.

4.) Zero-dimensional nanomaterials (Quantum Dot): These nanomaterials have all three dimensions in the nanoscale i.e., no dimensions are greater than $100 nm$. It is also called quantum dots. This means that the particles of material are confined in all three dimensions. It includes Nanospheres and nanoclusters.

B.) On the basis of materials: Nanomaterials can be categorized on the basis of material into four types such as:

1.) Inorganic-based nanomaterials (Metal-based materials ):

2.) Carbon-based nanomaterials:

3.) Organic-based nanomaterials (Dendrimers):

4.) Composite-based nanomaterials.

1.) Inorganic-based nanomaterials (Metal-based materials ): Generally, inorganic-based nanomaterials include different metal and metal oxide nanomaterials.

Examples of metal-based inorganic nanomaterials - silver $(Ag)$, gold $(Au)$, aluminum $(Al)$, cadmium $(Cd)$, copper $(Cu)$, iron $(Fe)$, zinc $(Zn)$, and lead $(Pb)$ nanomaterials.

Examples of metal oxide-based inorganic nanomaterials- zinc oxide $(ZnO)$, copper oxide $(CuO)$, magnesium aluminum oxide $(MgAl_{2}O_{4})$, titanium dioxide $(TiO_{2})$, cerium oxide $(CeO_{2})$, iron oxide $(Fe_{2}O_{3})$, silica $(SiO_{2})$, and iron oxide $(Fe_{3}O_{4})$, etc.

(2) Carbon-based nanomaterials: Carbon-based nanomaterials are graphene, fullerene, single-walled carbon nanotube, multi-walled carbon nanotube, carbon fiber, activated carbon, and carbon black.

(3) Organic-based nanomaterials (Dendrimers): The organic-based nanomaterials or dendrimers (i.e. Dendrimers are repetitively branched molecules. Dendrimers name comes from the Greek word ‘dendron’ which means tree.) are formed from organic materials that do not include carbon materials, for instance, dendrimers, cyclodextrin, liposome, and micelle.

(4) Composite-based nanomaterials: The composite nanomaterials can be any combination of all nanomaterials like metal-based, carbon-based, metal oxide-based, and organic-based nanomaterials. These composite nanomaterials have very complicated structures like a metal-organic framework.