Surface modification of TiO₂ nanocrystals by WOx coating or wrapping
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 se...
| Autores: | , , , , , , , , , , |
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| Formato: | artículo |
| Fecha de publicación: | 2015 |
| País: | España |
| Recursos: | Universitat Autònoma de Barcelona |
| Repositorio: | Dipòsit Digital de Documents de la UAB |
| Idioma: | inglés |
| OAI Identifier: | oai:ddd.uab.cat:200199 |
| Acesso em linha: | https://ddd.uab.cat/record/200199 https://dx.doi.org/urn:doi:10.1021/acsami.5b00632 |
| Access Level: | acceso abierto |
| Palavra-chave: | Gas sensors Metal oxide nanocrystals Nanocomposites Solvothermal synthesis Surface modification TiO₂ |
| Resumo: | 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. |
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