Highly photoactive ZnO by amine capping-assisted hydrothermal treatment

• Published in: Applied catalysis. B, Environmental Vol. 83; no. 1-2; pp. 30 - 38
• Main Authors: Colón, G., Hidalgo, M.C., Navío, J.A., Pulido Melián, E., González Díaz, O., Doña Rodríguez, J.M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.09.2008; Elsevier
• Subjects: Catalysis; Chemistry; Colloidal gels. Colloidal sols; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Hydrothermal; Indexing in process; Photocatalysis; Photochemistry; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); Q1; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Triethylamine; ZnO; ZnO; Hydrothermal; Photocatalysis; Triethylamine; Capping; Binary compound; Correlation; Heat treatment; Nanoparticle; Alcohol; Precipitate; Photochemical reaction; Template; Characterization; Crystallites; Precipitation; Hydrothermal treatment; Surface properties; pH; Defect; Transition element compounds; Crystallinity; Conversion; Heterogeneous catalysis; Phenol; Sol gel process; Tertiary amine; Phenols; Benzenic compound; Surface area; Titanium oxide; Hydrothermal condition; Environmental protection
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2008.01.033

ZnO nanoparticles have been prepared by amine template assisted sol–gel precipitation and further hydrothermal treatment. We have investigated the effect of different pH values achieved by means of triethylamine (TEA) addition in the final surface and structural properties. Two sets of samples were obtained after thermal treatment, one with no hydrothermal pre-treatment and a second hydrothermally pre-treated. Surprisingly the precipitate obtained after the amine addition also exhibits good photocatalytic properties. It has been stated that calcination treatment leads in both sets of samples to a significant improvement in the photocatalytic properties of the studied systems. Therefore, interesting comparison has been performed between hydrothermal pre-treated and direct thermal treated samples. Surface and morphological features notably differ from ZnO prepared using different synthetic route. Wide surface and structural characterization of the samples have been carried out, and correlations with precipitation pH are pointed out from this characterization. In all cases, the amine templated ZnO obtained exhibit high conversion values for phenol photo-oxidation reaction. Further calcination treatment in all of the studied samples clearly leads to photocatalytic conversions higher than that exhibited by TiO2 Degussa P25. This fact is even more significant if we consider that hydrothermally and calcined ZnO exhibit almost null surface area values, leading to a startling intrinsic photoactivity. The structural excellence (crystallinity, lack of defects, crystallite size, etc.) of such systems is clearly responsible for their high photoactivity values.