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Beyond shape engineering of TiO2 nanoparticles: Post-synthesis treatment dependence of surface hydration, hydroxylation, Lewis acidity and photocatalytic activity of TiO2 anatase nanoparticles with dominant {001} or {101} facets

  • TiO2 anatase nanoparticles are among the relevant players in the field of light-responsive semiconductor nanomaterials used to face environmental and energy issues. In particular, shape-engineered TiO2 anatase nanosheets with dominant {001} basal facets gained momentum because of the possibility to exploit different and/or improved functional behaviors with respect to usual bipyramidal TiO2 anatase nanoparticles, mainly exposing {101} facets. Nevertheless, such behavior depends in a significant extent on the physicochemical features of surfaces exposed by nanosheets. They can vary in dependence on the presence or removal degree of capping agents, namely, fluorides, used for shape-engineering, and experimental investigations in this respect are still a few. Here we report on the evolution of interfacial/ surface features of TiO2 anatase nanosheets with dominant {001} facets from pristine nanoparticles fluorinated both in the bulk and at their surface to nanoparticles with F− freeTiO2 anatase nanoparticles are among the relevant players in the field of light-responsive semiconductor nanomaterials used to face environmental and energy issues. In particular, shape-engineered TiO2 anatase nanosheets with dominant {001} basal facets gained momentum because of the possibility to exploit different and/or improved functional behaviors with respect to usual bipyramidal TiO2 anatase nanoparticles, mainly exposing {101} facets. Nevertheless, such behavior depends in a significant extent on the physicochemical features of surfaces exposed by nanosheets. They can vary in dependence on the presence or removal degree of capping agents, namely, fluorides, used for shape-engineering, and experimental investigations in this respect are still a few. Here we report on the evolution of interfacial/ surface features of TiO2 anatase nanosheets with dominant {001} facets from pristine nanoparticles fluorinated both in the bulk and at their surface to nanoparticles with F− free surfaces by treatment in a basic solution and to totally F− free nanoparticles by calcination at 873 K. The nanoparticles fluorine content and its subsequent evolution is determined by complementary techniques (ion chromatography, TOF-SIMS, XPS, AES, SEM-EDX), probing different depths. In parallel, the evolution of the electronic properties and the Ti valence state is monitored by UV−vis spectroscopy and XPS. The calcination treatment results in {001} facets poorly hydroxylated, hydrated, and hydrophilic, which appear as surface features consequent to the expected (1 × 4) reconstruction. Moreover, IR spectroscopy of CO adsorbed as probe molecule indicates that the Lewis acidity of Ti4+ sites exposed on (1 × 4) reconstructed {001} facets of calcined TiO2 nanosheets is weaker than that of cationic centers on {101} facets of bipyramidal TiO2 anatase nanoparticles. The samples have also been tested in phenol photodegradation highlighting that differences in surface hydration, hydroxylation, and Lewis acidity between TiO2 nanoparticles with nanosheet (freed by F− by calcination at 873 K) and bipyramidal shape have a strong impact on the photocatalytic activity that is found to be quite limited for the nanoparticles mainly exposing (1 × 4) reconstructed {001} facets.zeige mehrzeige weniger

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Metadaten
Autor*innen:L. Mino, F. Pellegrino, Steffi Rades, Jörg RadnikORCiD, Vasile-Dan HodoroabaORCiD, G. Spotto, V. Maurino, G. Martra
Dokumenttyp:Zeitschriftenartikel
Veröffentlichungsform:Verlagsliteratur
Sprache:Englisch
Titel des übergeordneten Werkes (Englisch):ACS Applied Nano Materials
Jahr der Erstveröffentlichung:2018
Organisationseinheit der BAM:6 Materialchemie
6 Materialchemie / 6.1 Oberflächen- und Dünnschichtanalyse
Verlag:ACS Publications
Verlagsort:Washington, DC, U.S.A.
Jahrgang/Band:1
Ausgabe/Heft:9
Erste Seite:5355
Letzte Seite:5365
DDC-Klassifikation:Naturwissenschaften und Mathematik / Chemie / Analytische Chemie
Freie Schlagwörter:F- doping; Nanoparticles; Nanosheets; Shape-controlled nanoparticles; TiO2
Themenfelder/Aktivitätsfelder der BAM:Chemie und Prozesstechnik
DOI:10.1021/acsanm.8b01477
ISSN:2574-0970
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:05.10.2018
Referierte Publikation:Ja
Datum der Eintragung als referierte Publikation:21.03.2019
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