IRIS – Institutional Research Information System
IRIS è il sistema di gestione della ricerca dell’Università degli Studi di Milano-Bicocca.Il repository BOA è il modulo del sistema dedicato alla raccolta e alla disseminazione della produzione scientifica di Ateneo. Le pubblicazioni sono ricercabili per parola chiave attraverso il box nella barra orizzontale in alto oppure, mediante il pulsante Sfoglia, per "Afferenza", "Autore", "Titolo", "Tipologia" o "Settore scientifico-disciplinare".
IRIS contiene inoltre alcuni moduli dedicati alla registrazione dei progetti e dei contratti, e alla reportistica avanzata per le attività di valutazione della ricerca
EnglishThe sol-gel synthesis of TiO<sub>2</sub> from TiCl<sub>4</sub> assisted by the triblock copolymer EO<sub>20</sub>-PO<sub>70</sub> -EO<sub>20</sub> (EO = -CH<sub>2</sub>CH<sub>2</sub>O-, PO = -CH<sub>2</sub> (CH<sub>3</sub>)CHO-) as templating agent was carried out by systematically changing H<sub>2</sub>O:Ti (r<sub>w</sub>) and HCl:Ti (r<sub>a</sub>) molar ratios. Mesoporous and nanocrystalline TiO<sub>2</sub> samples with well-defined and controlled phase composition (anatase, rutile, and mixed phase) were obtained after calcination at 400 °C and characterized for the morphology, particle size, and shape using TEM, HRTEM, XRD, and surface area measurements. The role of r<sub>w</sub> and r<sub>a</sub> and influence of the copolymer in determining the phase composition was demonstrated. Rutile becomes the main phase by increasing r<sub>w</sub>. In fact, the decrease of Ti concentration slows down the condensation rate, favoring formation of rutile seeds in the gel. The photocatalytic activity of TiO<sub>2</sub> in the UV photomineralization of phenol depends on the phase composition and oxidizing agent, H<sub>2</sub>O<sub>2</sub> or O<sub>2</sub>. When the oxidation is performed by H2O<sub>2</sub>, rutile, formed by large crystalline rods with high aspect ratios (size 15-20 × 100-120 nm), shows higher catalytic activity with respect to the small, almost cubic, anatase particles (5-15 nm). If O<sub>2</sub> is used, the catalytic activity generally decreases and the behavior of polymorphous species is reverse. EPR investigation of the paramagnetic charge carriers, formed under UV irradiation at 10 K, showed the resonance lines of holes trapped at O<sup>-</sup> lattice sites and electrons trapped at Ti<sup>3+</sup> and O<sub>2</sub><sup>-</sup> sites. The rutile crystalline rods present the largest quantity of O<sup>-</sup> and Ti<sup>3+</sup> centers. The overall results suggest correlation between TiO<sub>2</sub> particle size and shape and the photocatalytic activity and indicate that electron-hole recombination is the most probable rate-controlling process. © 2008 American Chemical Society.
http://hdl.handle.net/10281/6337| Citazione: | Scotti, R., Bellobono, I.R., Canevali, C., Cannas, C., Catti, M., D’Arienzo, M., et al. (2008). Sol-gel pure and mixed-phase titanium dioxide for photocatalytic purposes: relations between phase composition, catalytic activity, and charge-trapped sites. CHEMISTRY OF MATERIALS, 20(12), 4051-4061. |
| Tipo: | Articolo in rivista - Articolo scientifico |
| Carattere della pubblicazione: | Scientifica |
| Titolo: | Sol-gel pure and mixed-phase titanium dioxide for photocatalytic purposes: relations between phase composition, catalytic activity, and charge-trapped sites |
| Autori: | Scotti, R; Bellobono, IR; Canevali, C; Cannas, C; Catti, M; D’Arienzo, M; Musinu, A; Polizzi, S; Sommariva, M; Testino, A; Morazzoni, F |
| Autori interni: | SCOTTI, ROBERTO MORAZZONI, FRANCA CANEVALI, CARMEN CATTI, MICHELE D'ARIENZO, MASSIMILIANO |
| Data di pubblicazione: | 2008 |
| Lingua: | English |
| Rivista: | CHEMISTRY OF MATERIALS |
| Appare nelle tipologie: | 01 - Articolo su rivista |
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