Synthesis and Characterization of ZnCr₂O₄ Nanospinel Prepared via Homogeneous Precipitation Using Urea Hydrolysis

Abstract

In situ and homogeneous hydrolysis of urea was utilized to design a homogeneous precipitation method to synthesize the ZnCr2O4 functional material. The as‐prepared nanospinel was systematically studied in terms of crystal structure, morphology, texture, and light absorption. A well‐crystalline single phase of ZnCr2O4 nanospinel with a spongy network structure was obtained. Transmission electron microscopy and X‐ray diffraction observations confirmed the formation of monocrystalline nanoparticles of ZnCr2O4 with the nanosize of 13 nm. The synthesized nanospinel showed a low direct band gap value of 1.8 eV with appropriate absorption in the visible light region, which was a remarkable result for this route.

Tailoring the reducibility and catalytic activity of CuO nanoparticles for low temperature CO oxidation

“…22,23 Of particular interest, the UAHP method has attracted great attention owing to the fairly simple synthesis at mild temperature and ambient pressure, low cost processing and ease scalability. [24][25][26] In addition, this method permits the controlled formation of metal oxide structures from solutionphase precursors such as metal salts in aqueous media and the low-supersaturation conditions derived by slow urea hydrolysis give rise to formation of smaller number of nuclei formed which nally leads to well-crystallized solid material.…”

In situ synthesis of Al2O3‐supported ZnCr2O4 nanoparticles for application as an activated photocatalyst

“…It can be concluded that the nuclei and/or crystallites of Al 2 O 3 could be synthesized during drying; therefore, its related peaks are tiny and wide. The porous structure of the ZnCr 2 O 4 powder is also provided in Figure 4E (This figure has been originally published in the previous work 24 ). Figure 4 shows the FE-SEM images of the dried precipitate (Figure 4A,B) and the calcined powder ( Figure 4C,D) of Al 2 O 3 -ZnCr 2 O 4 .…”

“…As can be seen, the thermal behaviors of both samples are similar and the temperature region in which the unique exothermic reaction occurred is 300-500°C. 24 The third pattern is related to the aim of this manuscript namely the Al/Zn/Cr containing solution. However, commenting on this subject needs more characterizations.…”

“…One of the leading studies is by Peng et al They have been used a simple hydrothermal route to synthesize ZnCr 2 O 4 NPs with average particle size of 5 nm and direct band gap about 3.46 eV. 23 As described elsewhere, 24 ZnCr 2 O 4 NPs (with the average particle size of 13 nm) have been prepared by a simple and cheap homogeneous precipitation method using urea hydrolysis followed by heat treatment at 500°C. The average crystallite size and a s are approximately 60 nm and 77 m 2 /g.…”

Chromium-modified zinc oxides

“…The decrease of total pore volume and mean pore diameter is observed with an increase of chromium content. High surface area or low crystallite size of the oxides could be obtained under optimal Cr/Zn ratio and calcination temperature [31,32]. Accordingly, formation of ZnO-Cr-x high surface area materials can be connected with the presence of surface chromium phases, which may hinder fast growth and sintering of ZnO grains during precipitation and thermal treatment.…”