Photocatalytic and photoelectrochemical properties of hierarchical mesoporous TiO2 microspheres produced using a crown template

• Published in: Journal of photochemistry and photobiology. A, Chemistry. Chemistry., 2017-02, Vol.334, p.26-35
• Main Authors: Stroyuk, Oleksandr L., Ermokhina, Natalia I., Korzhak, Ganna V., Andryushina, Natalya S., Shvalagin, Vitaly V., Kozytskiy, Andriy V., Manoryk, Petro A., Barakov, Roman Yu, Kuchmiy, Stepan Ya, Shcherbatyuk, Mykola, Sapsay, Vitaly I., Puziy, Alexander M.
• Format: Article
• Language: English
• Subjects: Benzene oxidation; Hydrogen evolution; Mesoporous materials; Photocatalysis; Photoelectrochemistry; Titania
• ISSN: 1010-6030; 1873-2666
• DOI: 10.1016/j.jphotochem.2016.10.039

[Display omitted] •Mesoporous hierarchical TiO2 microspheres (MSs) were produced using dibenzo-18-crown-6.•TiO2 MSs were used as a photocatalyst of H2 production, benzene, and ethanol oxidation.•MSs supersede TiO2 Evonik P25 in photocatalytic activity.•MSs can be used as photoanode materials in liquid-junction solar cells. Mesoporous hierarchical TiO2 microspheres (MSs) with a size of 1–3μm and an average pore size of 12.2–17.5nm composed of smaller spherical 40–60-nm aggregates of discrete ∼10-nm anatase nanocrystals (NCs) were produced by the sol-gel transformation of Ti(IV) tetra butoxide in the presence of dibenzo-18-crown-6. Photocatalytic and photoelectrochemical properties of the TiO2 MSs were studied in several processes important for the sustainable light-to-energy conversion and environmental photocatalysis. In particular, the TiO2 MSs were found to be a much more efficient photocatalyst of the water reduction and the gas-phase oxidation of benzene and ethanol than irregularly aggregated mesoporous TiO2 and a benchmark Evonik P25 TiO2. The MSs also revealed an advanced photoelectrochemical activity. The most probable reasons for the high photochemical activity of the MSs are (i) the effect of multiple scattering and reflection of light passing through the MSs that increases the probability of light absorption and (ii) the electron transport through the framework of interconnected loosely aggregated anatase NCs that results in suppression of the electron-hole recombination. In the photoelectrochemical cells based on the MS/CdS heterostructures the light is absorbed by a thin layer of the visible-light-sensitive CdS NCs and the advantages of the MSs are leveled off, the activity of TiO2 as an electron transporting layer most probably limited by electrons leakage to the electrolyte.