Synthesis of ZnO nanoparticles by a hybrid electrochemical-thermal method: influence of calcination temperature

Abstract

ZnO nanoparticles (NPs) with size less than 100 nm were successfully prepared by a hybrid electrochemical-thermal method using metallic zinc and NaHCO 3 without the use of any zinc salt, template or surfactant. The NPs were characterized by Fourier transform infra-red (FT-IR) spectroscopy, UV-visible spectroscopy, photoluminescence spectroscopy (PL), thermo-gravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. UV-visible spectral analysis indicated that the particle size increased with increasing calcination temperature. The band gap (3.91-3.83 eV) was higher for synthesized ZnO NPs than their bulk counterparts (3.37 eV). The FT-IR spectra at different calcination temperatures showed the characteristic band for ZnO at 450 cm -1 to be prominent with increasing temperature due to the conversion of precursor into ZnO. The wurtzite hexagonal phase was confirmed by XRD analyses for ZnO NPs calcined at 700 o C. The green photoluminescent emission from ZnO NPs at different calcination temperatures is considered to be originated from the oxygen vacancy or interstitial related defects in ZnO. SEM images clearly showed that the NPs are granular and of almost uniform size when calcined at higher temperatures. EDX spectra further confirmed the elemental composition and purity of ZnO obtained on calcination at 700 o C. The NPs are well dispersed near or above calcination temperature of 700 o C.

Room temperature sintering of polar ZnO nanosheets: II-mechanism

“…As an example, this has been used to estimate the specific surface area of mesoporous silica materials by relating it to the ratio of the integrated area of the band ascribed to surface silanol to the integrated area of the band corresponding to bulk Si-O-Si bonds [22]. However, this technique cannot be applied in our case to track the variation of the specific surface area of the different functionalities with storage time because the area of the Zn-O-Zn bands (those below 600 cm -1 ) does not appear to be proportional to the total irradiated ZnO weight, since in several revised works [23][24][25] they show apparently random variations with this parameter. To overcome this problem, we will assume that the surface alkanes (#33 and #34 bands) were produced during the calcination of the hydrozincite precursor and have remained unaltered during unprotected storage.…”

Synthesis of Fe₃O₄ and Fe₂O₃ nanoparticles using hybrid electrochemical-thermal method

“…Furthermore, iron oxyhydroxide was synthesized by electro-chemical method (Uddin et al, 2007). Recently, a successful method for the preparation of ZnO nanoparticles by a hybrid electrochemical-thermal method has been reported from our laboratory (Hassan et al, 2015;Shohel et al, 2016). However, it is still a challenge to develop simple methods for the preparation of α-Fe 2 O 3 NPs.…”

Sol-gel, hydrothermal, and combustion synthetic methods of zinc oxide nanoparticles and their modification with polyaniline for antimicrobial nanocomposites application

“…The two transverse optical stretching modes of ZnO is observed at ~ 472 cm −1 associated with a strong shoulder at around 500 cm −1 which confirms the formation of ZnO NPs [29]. Additional absorptions emerged at 1630 cm −1 , 3425 cm −1 and 1120 cm −1 in the spectra of ZnO-M1, ZnO-M2, and ZnO-M3 due to water, OH on the surface of ZnO NPs and reaction intermediates such as Zn hydroxoacetate complex or zinc acetate cluster (Zn 4 O(CH 3 COO) 6 ).…”

“…This includes the selection of reactants, their concentrations, and the reaction condition. For example; the calcination temperature has a great influence on the morphology and the size of the synthesized ZnO [6][7][8][9]. Matei et al [3] presented the most common techniques used for the synthesis of ZnO NPs such as; mechanochemical [10], precipitation [11][12][13], emulsion [14], sol-gel [15,16], microwave [17], hydrothermal [18], combustion [5,19], sonochemical synthesis [20].…”