Home» Zinc Oxide Nanoparticles
Nanotechnology research has gained momentum in the recent years by providing innovative solutions in the field of biomedical, materials science, optics and electronics. Nanoparticles are essentially a varied form of basic elements derived by altering atomic and molecular properties of elements. This article elaborates on the properties and applications of zinc oxide nanoparticles. Zinc oxide (ZnO) nanopowders are available as powders and dispersions. These nanoparticles exhibit antibacterial, anti-corrosive, antifungal and UV filtering properties. Zinc is a Block D, Period 4 element while Oxygen is a Block P, Period 2 element. Some of the synonyms of zinc oxide nanoparticles are oxydatum, zinci oxicum, permanent white, ketozinc and oxozinc.
Zinc oxide (ZnO) nanoparticles have their own importance due to their vast area of applications, e.g. gas sensor, chemical sensor, bio-sensor, cosmetics, storage, optical and electrical devices window materials for displays, solar cells, and drug-delivery. ZnO is an attractive material for short-wavelength optoelectronic applications owing to its wide band gap 3.37 eV, large bond strength, and large exciton binding energy (60 meV) at room temperature. As a wide band gap material, ZnO is used in solid state blue to ultraviolet (UV) optoelectronics, including laser developments. In addition, due to its non-symmetric crystallographic phase ZnO shows the piezoelectric property, which is highly useful for the fabrication of devices, such as electromagnetic coupled sensors and actuators.
Crystalline ZnO has a wurtzite (B4) crystal structure at ambient conditions. The ZnO wurtzite structure has a hexagonal unit cell with two lattice parameters a and c belongs to the space group of C4 6V or P63mc. Figure 1 clearly shows that the structure is composed of two interpenetrating hexagonal closed packed (hcp) sub lattices.
Zinc oxides nanoparticles show a pronounced biological activity. They are used both independently and in complexes with organic compounds. These nanoparticles are not only capable of inhibiting aggregation of colloid solutions and increase their stability but also can deliver medical preparations to the target location of pathological process. In particular, nanozinc has been used in nonorganic complexes with different chemical elements such as ZnS, ZnO etc.
Properties of Zinc oxide Nanoparticles
Nanosized particles of semiconductor materials have gained much more interest in recent years due to their desirable properties and applications in different areas such as catalysts, sensors, photoelectron devices, highly functional and effective devices. These nanomaterials have novel electronic, structural and thermal properties which are of high scientific interests in basic and applied fields.
Zinc oxide (ZnO) is a wide band gap semiconductor with an energy gap of 3.37 eV at room temperature. It has been used considerably for its catalytic, electrical, optoelectronic, and photochemical properties. ZnO nanostructures have a great advantage to apply in a catalytic reaction process due to their large surface area and high catalytic activity. Since zinc oxide shows different physical and chemical properties depending upon the morphology of nanostructures, by not only various synthesis methods but also the physical and chemical properties of synthesized zinc oxide are to be investigated in terms of its morphology.
|Molar Mass||81.40 g/mol|
|Melting Point||1975 °C|
|Boiling Point||2360 °C|
|Electronic config.||Zinc [Ar] 3d10 4s2 Oxygen [He] 2s2 2p4|
Applications of Zinc Oxide Nanoparticles
ZnO nanomaterials have been used as semiconductors in microelectronic devices and for accelerating degradation of water pollutants via photocatalytic activity. Due to its inherent ability to absorb UV irradiation and optical transparency, ZnO nanoparticles are used in the cosmetic industry, typically in sunscreens and facial creams. Their recognized antibacterial properties are also encouraging a variety of antimicrobial applications.
ZnO nanoparticles have gained interest in other biomedical applications based on their high stability, inherent photoluminescence properties which can be useful in biosensing applications, wide band-gap semiconductor properties useful in photo catalytic systems and promotion of reactive oxygen species generation.
ZnO nanoparticles have recently shown promising application as cholesterol biosensors, dietary modulators for hydrolase activity relevant to controlling diabetes and hyperlipaemia, as well as cell imaging. Additionally, ZnO nanoparticles are favourable in modulating allergic reactions via inhibition of mast cell degranulation. The diversity of these activities has popularized ZnO nanomaterials in interdisciplinary research communities involving physicists, chemists and biologists.
ZnO is nontoxic; it can be used as photocatalytic degradation materials of environmental pollutants. Bulk and thin films of ZnO have demonstrated high sensitivity for many toxic Gases. Researchers concluded that the potential use of ZnO nanoparticles for antibacterial activity. Extensive discussion was centered on the antibacterial activity of ZnO nanoparticles coupled with a number of influenced factors impacting the activity. Mainly, by improving factors like UV illumination, ZnO particle size, concentration, morphology, and surface modification, powerful antibacterial results would be obtained.
In addition to the above applications, i.e., gas sensors, chemical and biosensors, light emitting diodes, photo-detectors, and photo catalytic application, ZnO nanoparticles also exhibit tremendous UV-blocking properties. Generally, sunlight consists of three types of UV radiation, i.e., UV-A (320–400 nm), UV-B (290–320 nm), and UV-C (250–290 nm). Generally, to protect the skin, materials having UV-blocking properties are added to cosmetic formulations. For the protection of skin from UV-A radiation,
ZnO nanoparticles provided an effective UV-blocking material compared to TiO2. Generally, ZnO nanoparticles effectively absorb UV-A radiation rather than scatter it, but TiO2 usually scatters these wavelengths. Although ZnO absorption for UV-A radiation is good compared to TiO2, photocatalytic activity hinders its possible application in cosmetic formulations. In addition, due to the high photo catalytic activity of ZnO, reactive oxygen species are generated, which can oxidize ingredients involved in the cosmetic formulation.