Investigations of a Statistical and Analytical Method to Find the Relationship between the Morphological and Optical Properties of ZnO Nanoflower Arrays

Abstract

In this study, a sapphire substrate with a patterned concave structure was used to prepare ZnO film/A-B glue, and the ZnO film/A-B glue with a patterned convex matrix was transferred onto a silicon wafer using the lift-off technology as the seed layer. Then, the hydrothermal method with different Zn(CH 3 COO) 2 and C 6 H 12 N 4 concentrations as precursors was used to synthesize ZnO nanoflower arrays on the patterned convex ZnO seed layer. XRD pattern, FESEM, FIB, and photoluminescence (PL) spectrometry were employed to observe and analyze the properties of the synthesized ZnO nanoflower arrays. When Zn(CH 3 COO) 2 and C 6 H 12 N 4 concentrations were 0.01, 0.02, 0.03, and 0.04 M, the average heights of the ZnO nanorods in the ZnO nanoflower arrays were 993, 1500, 1550, and 1650 nm, the average diameters of the ZnO nanorods were 50, 90, 105, and 225 nm, and the aspect ratios ( H / D ) of the ZnO nanorods were 19.9, 16.7, 14.8, and 7.33, respectively. A simple statistical and analytical method was investigated to estimate the densities (number of nanorods) of the ZnO nanoflower arrays in one 1 μm × 1 μm area. The total surface area ( S ) of the ZnO nanoflower arrays first increased from 5.05 × 10 6 and then reached a maximum value of 1.20 × 10 7 nm 2 as Zn(CH 3 COO) 2 and C 6 H 12 N 4 concentrations increased from 0.01 to 0.02 M. For the systhesized ZnO nanoflower arrays, as the Zn(CH 3 COO) 2 and C 6 H 12 N 4 concentrations increased from 0.01 to 0.04 M, their total volume ( V ) increased from the 6.23 × 10 7 to 5.90 × 10 8 nm 3 and the S / V ratio decreased from 8.10 × 10 –2 to 1.84 × 10 –2 . We found that ZnO nanoflower arrays with Zn(CH 3 COO) 2 and C 6 H 12 N 4 concentrations of 0.2 M presented the maximum PL emission intensities. The calculated S / V ratios and X-ray photoelectron spectroscopy analyses are used to discuss the reasons for these results.

Impact on the Photocatalytic Dye Degradation of Morphology and Annealing-Induced Defects in Zinc Oxide Nanostructures

“…Pristine, element-doped zinc oxide (ZnO), and the construction of heterojunctions with various semiconductors have made ground in many solar-related applications, such as energy conversion and storage, solar water splitting, solar cells, and photocatalytic water treatment. − Especially, ZnO nanomaterials maintain their popularity due to their high optical absorption, high resistivity against photocorrosion, easy manipulation of morphology, and electrical and catalytic properties. − Nanostructure engineering provides various morphologies with the advantages of a large surface-to-volume ratio and high electron mobility compared to bulk nanoparticles. − Besides, the optical properties of ZnO nanostructures are highly influenced by the size, morphology, synthesis methods/reaction conditions, types of precursors, and utilization of various surfactant materials. − Das et al have reported that the use of trisodium citrate as a surfactant during the hydrothermal synthesis resulted in morphological changes . The presented ZnO morphologies produced in the presence of citrate exhibited novel photoluminescence properties and enhanced photocatalytic efficiency compared to ZnO formed without a surfactant.…”

Use of Concave Sapphire Substrate to Synthesize ZnO Nanorod Arrays and Application of a Cu-decorated ZnO Nanorod Array Gas Sensor

“…A square with an area of 1 μm 2 was then drawn around each of the five points, and the number of ZnO nanorods in each square was counted. (13,14) For synthesis times of 30, 45, and 60 min, the average numbers of ZnO nanorods in 1 μm 2 were 125, 116, and 48, respectively. As the growth time increased, the density of ZnO nanorods decreased and the diameter increased.…”

Synthesis of ZnO Nanoflower Arrays on Patterned Cavity Substrate and Their Application in Methylene Blue Degradation

“…A significant finding of this research is the development of an inexpensive technique to create a ZnO seed layer with a matrix and protrusion structure for synthesizing ZnO NFAs using a combination of template technology and the hydrothermal method for synthesizing one-dimensional ZnO-based nanomaterials. This approach involves the uses of patterned sapphire as templates and lift-off as the technology to create ZnO NFAs [ 11 , 12 ]. The synthesis results of ZnO NFAs were analyzed by varying the synthesis time while keeping the other parameters constant [ 13 ].…”