A Review on Low-Dimensional Nanomaterials: Nanofabrication, Characterization and Applications

Abstract

The development of modern cutting-edge technology relies heavily on the huge success and advancement of nanotechnology, in which nanomaterials and nanostructures provide the indispensable material cornerstone. Owing to their nanoscale dimensions with possible quantum limit, nanomaterials and nanostructures possess a high surface-to-volume ratio, rich surface/interface effects, and distinct physical and chemical properties compared with their bulk counterparts, leading to the remarkably expanded horizons of their applications. Depending on their degree of spatial quantization, low-dimensional nanomaterials are generally categorized into nanoparticles (0D); nanorods, nanowires, and nanobelts (1D); and atomically thin layered materials (2D). This review article provides a comprehensive guide to low-dimensional nanomaterials and nanostructures. It begins with the classification of nanomaterials, followed by an inclusive account of nanofabrication and characterization. Both top-down and bottom-up fabrication approaches are discussed in detail. Next, various significant applications of low-dimensional nanomaterials are discussed, such as photonics, sensors, catalysis, energy storage, diverse coatings, and various bioapplications. This article would serve as a quick and facile guide for scientists and engineers working in the field of nanotechnology and nanomaterials.

Keywords: characterization; layered materials; nanofabrication; nanoparticles; nanorods; quantum dots.

Figure 1

Classification of nanomaterials according to their confined dimensionality.

Figure 2

Illustration of “Top-down” and “Bottom-up” techniques for nanofabrication.

Figure 3

Types of photoresists.

Figure 4

Schematic diagram of scanning probe lithography.

Figure 5

Focused ion beam lithography.

Figure 6

Nanopore arrays fabricated by Ga⁺ ion milling in bare (a) and metallised (b) silicon-nitride membranes. The distorted pore geometries are result of the beam defocusing effect of electrically charged dielectric membrane [76].

Figure 7

A three-zone chemical vapor deposition (CVD) system.

Figure 8

Schematics of an ALD growth cycle. Reproduced with permission from [86]. Elsevier, 2014.

Figure 9

Schematic of MBE system. Reproduced with permission from [91]. Elsevier, 2012.

Figure 10

Characterization tools for nanomaterial characterization.

Figure 11

Schematic diagram of differential centrifugal sedimentation.

Figure 12

Illustration of basic photodegradation processes using TiO₂ photocatalyst.

Figure 13

Schematic diagram of energy level positions for CdS and other semiconductors relative to the redox potential of water. Reproduced with permission from [273]. Royal Society of Chemistry, 2020.

Figure 14

(a) The surface oxygen functional group of g-C₃N₄ nanorods can be evidenced by the appearance of the peak at 1780 cm⁻¹ which is due to the stretching and bending vibrations of carbonyl and carboxyl groups. (b) The high-resolution XPS spectra of O-1s with its deconvolution clearly reveal the presence of C=O and C−O. Reproduced with permission from [277]. John Wiley and Sons, 2019.