Strong visible photoluminescence emission of ZnO nanosheets and nanoflowers by a facile hydrothermal route

Abstract

Zinc oxide nanostructures such as nanosheets (NS) and nanoflowers (NF) were obtained by a facile hydrothermal synthesis using zinc chloride (ZnCl2) as precursor with low molar concentrations and a short synthesis time (2 h) at 200 °C. By means of X-ray diffraction and Raman spectroscopy measurements, the wurtzite-type ZnO structure was confirmed with high crystalline quality. SEM micrographs showed the influence of ZnCl2 concentration on ZnO morphology; ZnO NF were obtained at low concentrations (0.02 and 0.05 M), while ZnO NS were seen for higher concentrations (0.2–0.6 M) and their thicknesses can be estimated from 15 to 60 nm. In addition, TEM images showed a large number of pores with sizes below 15 nm in both ZnO nanostructures. Raman and photoluminescence displayed the surface defects density for ZnO nanostructures. Raman spectra showed the E1(LO) mode localized at ∼581 cm−1, associated with oxygen vacancies and zinc interstitials, being more intense for ZnO NF, while photoluminescence results showed a strong yellow-orange emission (centered from 587 to 618 nm) relative to UV emission, being more intense for ZnO NF. These properties reveal further potential for high performance luminescent devices based on ZnO NF and NS.

Hydrogen Ion Irradiation Effect on the Luminescence of MoS2Nanoflowers

“…The higher PL for NFs compared to bulk has already been reported in the literature; it was associated with the increase of the surface area, causing the increase in the density of the surface defects, therefore in electronic states associated to defects that might be localized inside the band gap. [ 60,61 ] For the NFs, after H 2 irradiation, the intensity of the PL peak increases with increasing the irradiation time. After 60 min of irradiation, the PL peak's intensity enhanced almost three times compared to the PL recorded on the as‐synthesized sample.…”

SCHOTTKY DIODE FABRICATION VIA COLD SUBSTRATE EVAPORATED Ag ON SOL-GEL DERIVED ZnO ULTRA-THIN FILMS FOR SEMICONDUCTOR DEVICES

“…Cheung and Cheung's functions can be calculated to determine the series resistance. Equation ( 11) can rearrange as follows; (12) According to Equation ( 12), the series resistance can be found from the slope and ideality factor is obtained by extrapolating the linear part of dV/d(ln I) versus I curve. If n = 1, the Equation ( 11) can be given as,…”

“…Improve the high-quality and suitable ohmic and rectifying contacts to achieve maximum efficiency is required for semiconductor devices. Fabrication of an intended quality rectifying contact on n-type ZnO crystal is harder because of high donor concentration at the surface field coming from defects such as oxygen vacancies (V o ) or zinc interstitials (Zn i ) or both [10][11][12] which affect the barrier height of metalsemiconductor.…”

Evaluation of Au nanosphere content on ZnO nanoparticle surfaces as reusable and durable plasmonic nanocatalysts

“…With this in mind, a facile, environment‐friendly, and rational synthetic strategies was used to obtain ZnO nanoparticles and Au/ZnO nanocatalysts with different Au contents onto the ZnO surface by hydrothermal synthesis and chemical reduction methods, respectively. The hydrothermal synthesis was chosen due its several advantages, as previously reported, 29 whereas chemical reduction method was employed due its simplicity and capability to obtain controllable Au nanosphere deposition on ZnO nanoparticles. This study demonstrates the importance of controlling the Au nanospheres loaded onto the ZnO surface to reach a better photocatalytic performance, including good photostability after some reuse cycles and a longer aging time compared with most of the nanocatalysts as composites based on ZnO that have been reported until now.…”