Size and Morphology Modulation in ZnO Nanostructures for Nonlinear Optical Applications: A Review

Abstract

Morphology-rich ZnO as a direct band gap II−VI semiconductor is a promising material for photonic, optical, and electronic devices. Nanostructured materials have provided a leading edge to the next-generation technology due to their distinguished performances and efficiencies for device fabrication. The nonlinear optical (NLO) properties and mechanisms dependent on the size and dimensionality of ZnO nanostructures remain to be elucidated. Herein, we begin to provide a comprehensive summary of the status of research activities in ZnO nanostructures, including their syntheses and potential applications, with an emphasis on multidimensional ZnO nanostructure based growth, properties, and applications. Density functional theory calculations confirmed the effect of ZnO size, morphology, and defect on the structure, work function, and charge density distribution of the electron band. Finite difference time domain simulation confirmed that the electric field, magnetic field, and Poynting vector of the ZnO system with the morphology changes were applied. Moreover, the ultrafast NLO and carrier dynamics of feature-rich ZnO nanostructures were studied. The effects of different experimental parameters on the morphology and linear and nonlinear excitation and radiation mechanisms of ZnO nanostructures were studied by constructing an electron transfer mechanism diagram and the Z-scan technique. The results show that the properties and properties of ZnO nanostructures can be regulated and controlled by the structure and morphology. The application and performance of feature-rich zinc oxide nanostructures in photoelectric functional devices are prospected, which will provide valuable references and guidance for related researchers.

Cu and Ni dual-doped ZnO nanostructures templated by cellulose nanofibrils for the boosted visible-light photocatalytic degradation of wastewater pollutants

“…ZnO morphology is vital for adjusting the photocatalytic performance. 35 Therefore, the photocatalytic activity of the ZnO@CNF nanocomposites towards MO degradation was determined by using blue light as the energy source. Pristine CNF showed negligible MO degradation efficiency (2.0%) and served as a blank control.…”

Growth of ZnO Polytypes: Multiple Facets of Diverse Applications

“…During the boom in nanoscience and nanotechnology, ZnO has been proven to be the richest in morphological diversity that plays a significant role in tuning the physicochemical characteristics at the nanoscale dimensions. A wide gamut of nanostructures with versatile geometries, such as zero-, one-, two-, and three-dimensional nanostructures, have been synthesized/fabricated because of the simplicity in the process of crystallization and anisotropic growth behavior . Zero-dimensional ZnO materials, such as quantum dots, nanospheres, nanoballs, etc., exhibit the abundance of grain boundaries, and as a consequence, these materials exhibit higher solubility as well as higher dissolution rates in comparison with bulk counterparts .…”

“…The growth of the bunches of ZnO nanoflowers that occurs along the (0001) crystallographic orientation results into the formation of flower-like structures . It has also been observed that the growth of ZnO nanowires and faceted nanotubes occurs along the [0001] direction ( c -axis) and they are enclosed by {100} surfaces, while the direction of growth of the ZnO nanoporous belts occurs parallel to the (0001) plane . It has also been revealed that the Zn-terminated (0001) surface can be stabilized through the spontaneous formation of a higher concentration of Zn-deficient pits of triangular shape and step edges that can be terminated with coordinated O atoms.…”

“…Intrinsic optical transitions occur between the electrons residing in the conduction band and the holes in the valence band as well as excitonic effects arising from the Coulomb interaction. Extrinsic optical properties are associated with the presence of dopants or defects that generate discrete electronic states within the band gap, and as a consequence, influence both the linear and nonlinear absorption and photoluminescence processes. These materials have also been considered as a promising material for many applications, such as a transparent conductive contact, varistors, surface electroacoustic wave devices, and heterojunction laser diodes .…”

“…It has been observed that the these hollow and template-free microstructures can act as greener catalysts for the Fries rearrangement of phenolic esters to p -hydroxyaryl carbonyl compounds with high turnover frequency . In addition, the possibility of tuning the band gap with particle size has been advantageous for the photocatalytic decompositions of volatile organic compounds . The unique advantages, including high environmental and electrical stabilities, high photoelectrical performance, and cost-effectiveness, have inspired the application of ZnO as typical photocatalysts toward industrial applications.…”