Influence of substituted acetic acids on "bridge" synthesis of highly photocatalytic active heterophase TiO2 in hydrogen production.

Autor: Cihlar, Jaroslav, Navarro, Lizeth Katherine Tinoco, Kasparek, Vit, Michalicka, Jan, Castkova, Klara, Lazar, Istvan, Kastyl, Jaroslav, Celko, Ladislav, Vesely, Michal, Dzik, Petr
Zdroj: Journal of Sol-Gel Science & Technology; Feb2023, Vol. 105 Issue 2, p471-488, 18p
Abstrakt: Anatase/brookite nanoparticles were prepared by low-temperature hydrolysis and polycondensation of titanium isopropoxide in the presence of low concentrations of acetic acid substituted in the α−position with Cl, F, NH2 or OH groups. A bridging mechanism described the formation of TiO2 with heterophase junctions between anatase and brookite. Substituted acetic acids formed short Ti---X-CH2-COO---Ti bridges that held neighboring Ti species close together and facilitated their condensation and the formation of Ti-O-Ti bonds. The structure of the anatase-brookite heterophase junctions was located and fully characterized by HR-TEM. The most acidic acetic acids substituted with groups with a strongly negative inductive effect, monochloroacetic, dichloroacetic, trichloroacetic, trifluoroacetic and amino acetic acids, supported the formation of TiO2, which in cooperation with the Pt cocatalyst had photocatalytic activity, 144.6–165.6 μmol H2/min. g, in the production of hydrogen. All photocatalysts had a pronounced mesoporous structure and a large specific surface area (212.6 to 247.2 m2/g), which contributed to the high photocatalytic activity. Highlights: Heterophase anatase-brookite nanoparticles were prepared by hydrolysis and polycondensation of titanium isopropoxide in a solution of substituted acetic acids. The bridges between substituted acetic acids and Ti atoms facilitate the formation of heterophase anatase-brookite junctions. Anatase-brookite heterophase junctions deposited by Pt nanoparticles formed photocatalytically active centers. acetic acids substituted with Cl-, F- and NH2- groups produced highly active photocatysts in hydrogen production. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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