Surface modification of TiO₂ nanocrystals by WOx coating or wrapping : solvothermal synthesis and enhanced surface chemistry
Epifani, Mauro (Istituto per la Microelettronica e i Microsistemi (Lecce, Itàlia))
Díaz, Raül (Instituto IMDEA Energía (Móstoles, Madrid))
Force, Carmen (Universidad Rey Juan Carlos)
Comini, Elisabetta (University of Brescia (Itàlia))
Manzanares, Marta (Institut de Recerca en Energia de Catalunya)
Andreu, Teresa (Institut de Recerca en Energia de Catalunya)
Genç, Aziz (Institut Català de Nanociència i Nanotecnologia)
Arbiol i Cobos, Jordi (Institut Català de Nanociència i Nanotecnologia)
Siciliano, Pietro (Istituto per la Microelettronica e i Microsistemi (Lecce, Itàlia))
Faglia, Guido (University of Brescia (Itàlia))
Morante, Joan Ramon (Institut de Recerca en Energia de Catalunya)

Data:	2015
Resum:	TiO₂ anatase nanocrystals were prepared by solvothermal processing of Ti chloroalkoxide in oleic acid, in the presence of W chloroalkoxide, with W/Ti nominal atomic concentration (Rw) ranging from 0. 16 to 0. 64. The as-prepared materials were heat-treated up to 500 °C for thermal stabilization and sensing device processing. For R₀. ₁₆, the as-prepared materials were constituted by an anatase core surface-modified by WOₓ monolayers. This structure persisted up to 500 °C, without any WO₃ phase segregation. For Rw up to R₀. ₆₄, the anatase core was initially wrapped by an amorphous WOₓ gel. Upon heat treatment, the WOₓ phase underwent structural reorganization, remaining amorphous up to 400 °C and forming tiny WO₃ nanocrystals dispersed into the TiO₂ host after heating at 500 °C, when part of tungsten also migrated into the TiO₂ structure, resulting in structural and electrical modification of the anatase host. The ethanol sensing properties of the various materials were tested and compared with pure TiO₂ and WO₃ analogously prepared. They showed that even the simple surface modification of the TiO₂ host resulted in a 3 orders of magnitude response improvement with respect to pure TiO₂.
Nota:	Ajuts: CSIC/CNR project 2010IT0001 (SYNCAMON), SOLAR project DM19447. JA and AZ acknowledge ICN2 Severo Ochoa Excellence Grant
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Matèria:	Gas sensors ; Metal oxide nanocrystals ; Nanocomposites ; Solvothermal synthesis ; Surface modification ; TiO₂
Publicat a:	ACS applied materials & interfaces, Vol. 7, no. 12 (Jan. 2015) , p. 6898-6908, ISSN 1944-8252

DOI: 10.1021/acsami.5b00632

Postprint 12 p, 5.6 MB

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