Thermal reactions in mixtures of micron-sized silicon monoxide and titanium monoxide: redox paths overcoming passivation shells

• Published in: Research on chemical intermediates Vol. 44; no. 1; pp. 503 - 516
• Main Authors: Jandová, V., Pokorná, D., Kupčík, J., Bezdička, P., Křenek, T., Netrvalová, M., Cuřínová, P., Pola, J.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 2018; Springer Nature B.V
• Subjects: Catalysis; Catalytic activity; Chemistry; Chemistry and Materials Science; Decoloring; Disproportionation; Fourier transforms; Inorganic Chemistry; Intermetallic compounds; Mixed oxides; Oxygen transfer; Particulate composites; Photocatalysis; Physical Chemistry; Silicides; Silicon; Silicon dioxide; Titanium oxides; Titanium monoxide; Oxygen-transfer reactions; Methylene blue depletion; Silicon monoxide; Titanium suboxides; Titanium silicide; High-temperature
• ISSN: 0922-6168; 1568-5675
• DOI: 10.1007/s11164-017-3116-z

Silica–titania mixed oxides and composites have been extensively studied, whereas the titanium monoxide (TiO)–silicon monoxide (SiO) counterparts still remain to be explored. Here, we report on structural changes in heated SiO–TiO mixtures. The changes in composition in intimately mixed μm-sized particles of TiO and SiO heated at 1000 °C were examined by FTIR, UV–Vis and Raman spectroscopy, X-ray diffraction and electron (SEM and TEM) microscopy. They are shown to involve depletion of crystalline TiO and formation of titanium suboxides (Ti 2.5 O 3 , Ti 2 O 3 ), rutile, elemental silicon, titanium silicide Ti 5 Si 3 and amorphous binary SiO x , TiO x and ternary Si x Ti y O z nano-structures. These constituents of the developed Si/Ti/O composite are explained by SiO disproportionation, reduction of TiO by silicon, oxygen transfer (redox) reactions between TiO x and SiO x species and the combination of Ti and Si to obtain titanium silicide. The produced Si/Ti/O composite absorbs visible light and its solar-light photocatalytic activity in decolorization of methylene bBlue is compared to that of the unheated SiO, TiO and Ti 5 Si 3 powders.