Oxygen vacancies on Pd/TiO2 are detected at low pressures by ESR spectroscopy at ambient temperatures

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ÜNER D., YARAR M.

Turkish Journal of Chemistry, cilt.46, sa.4, ss.1081-1088, 2022 (SCI-Expanded) identifier identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 46 Sayı: 4
  • Basım Tarihi: 2022
  • Doi Numarası: 10.55730/1300-0527.3416
  • Dergi Adı: Turkish Journal of Chemistry
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Chemical Abstracts Core, TR DİZİN (ULAKBİM)
  • Sayfa Sayıları: ss.1081-1088
  • Anahtar Kelimeler: Room temperature electron spin resonance (ESR), room temperature electron paramagnetic resonance (EPR), low pressure ESR, saturation-recovery CW-ESR, TIO2, ELECTRON, ANATASE, EPR, RADICALS, SURFACE, STATES
  • Orta Doğu Teknik Üniversitesi Adresli: Evet

Özet

© 2022 TUBITAK. All rights reserved.A low field benchtop electron spin resonance (ESR) (also referred to as electron paramagnetic resonance (EPR)) spectrometer is used to reveal paramagnetic centres such as oxygen vacancies and Ti+3 centres over 0.5%Pd/TiO2. The measurement was performed at room temperature after the sample was reduced in situ under mild hydrogen pressures and evacuated to P < 10–6 Torr. The measurement was possible due to a T1 compensation effect under vacuum: Correlation times at low pressures enabled sufficient line narrowing and detection of the ESR signal, justifying a method using benchtop spectrometers coupled to vacuum manifolds. The method justification was demonstrated using similar measurements performed on a reference compound, Mn(II) in plasticine: a measurement performed by saturation recovery technique revealed that T1 of the signal due to Mn(II) was smaller in vacuum than its atmosphere exposed counterpart. By applying vacuum, the ESR spectra of 0.5%Pd/TiO2 were collected at ambient temperatures, with features equivalent to the published data obtained at cryogenic temperatures.