Details

Autor(en) / Beteiligte

• Liu, Chang
• Lu, Hongbing
• Zhang, Jinniu
• Gao, Jianzhi
• Zhu, Gangqiang
• Yang, Zhibo
• Yin, Feng
• Wang, Chunlan

Titel

Crystal facet-dependent p-type and n-type sensing responses of TiO2 nanocrystals

Ist Teil von

• Sensors and actuators. B, Chemical, 2018-06, Vol.263, p.557-567

Ort / Verlag

Elsevier B.V

Erscheinungsjahr

2018

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Both p-type and n-type sensing responses are revealed to be facet-dependent, demonstrating obvious increase of response with increasing {001} percentage. [Display omitted] •TiO2 nanocrystals with various percentages of exposed {001} facets were prepared.•Both p-type and n-type sensing responses of TiO2 nanocrystals were revealed to be facet-dependent.•The adsorption capabilities of ethanol molecules and surface oxygen species increased with increasing {001} percentage.•Absorbed oxygen ion species changed from O− to O2− at high percentage of exposed {001} facets.•The facet-dependent p-type and n-type sensing mechanisms of TiO2 nanocrystals were explored. TiO2 nanocrystals with various percentages of exposed {001} facets have been prepared by a hydrothermal approach in the presence of HF. The gas-sensing properties towards ethanol of the TiO2 nanocrystals are examined in detail. The sensors based on the TiO2 nanocrystals exhibit a regular n-type behavior above 250 °C and abnormal p-type sensing response at low temperatures (room temperature – 120 °C). Importantly, both the p-type and n-type sensing responses are revealed to be facet-dependent, demonstrating an obvious increase of response with the increase of the percentage of exposed {001} facets. Other n-type sensing properties including prefactor α and detection limit are also found to be {001} facet-dependent. The facet-dependent p-type sensing mechanism is attributed to the increased water molecules on TiO2 surface with increasing {001} percentage, while the facet-dependent n-type sensing mechanism is ascribed to the increased adsorption capabilities of ethanol molecules and surface oxygen species as well as the change of absorbed oxygen ions from O− to O2− with the increase of {001} percentage. The finding here provides some new insights into the facet-dependent gas sensing mechanism, which is beneficial to engineer sensing nanomaterials with enhanced sensing performances by exposing specific crystal facets.