In situ monitoring of NiO–Al2O3 nanoparticles synthesis by thermo-Raman spectroscopy

• Published in: Materials chemistry and physics Vol. 119; no. 1-2; pp. 86 - 92
• Main Authors: Ghule, Anil Vithal, Ghule, Kalyani, Punde, Tushar, Liu, Jen-Yu, Tzing, Shin-Hwa, Chang, Jia-Yaw, Chang, Hua, Ling, Yong-Chien
• Format: Journal Article
• Language: English
• Published: 15.01.2010
• Subjects: Chemical reactions; Fluorescence; Forming; Heating; Monitoring; Nanoparticles; Spectroscopy; Synthesis
• ISSN: 0254-0584
• DOI: 10.1016/j.matchemphys.2009.07.050

Simultaneous TGA and thermo-Raman spectroscopy (TRS) measurements for in-situ monitoring of the wet chemical reaction of Ni(OH)2.4H2O and Al(OH)3 forming NiO-Al2O3 nanoparticles were studied and compared with the solid-state reaction. A different approach of synthesis and monitoring of NiO-Al2O3 by TRS is presented, in which in-situ thermo-Raman spectra were recorded at every degree interval from 25 to 800 C to understand the structural and compositional changes in NiO-Al2O3 as a function of temperature. Slow controlled heating of the sample, as in TRS, enables better control over morphology and particle size distribution (about 10-20 nm diameter). XRD showed that a smaller particle size was obtained using the wet chemical reaction than the solid-state reaction (about 25 nm diameter). TRS studies also revealed that the bulk NiAl2O4 forms at temperatures above 800 C, although the onset of formation is around 600 C. Condensation of Al(OH)3 forming Al2O3 was also monitored, wherein the presence of hydrocarbon was found to contribute to the observed fluorescence background. Based on the TRS and complementary characterisations using XRD, SEM, TEM, and EDX, the formation of supported NiO-Al2O3 catalysts is discussed.