Interaction of indium oxide nanoparticle film surfaces with ozone, oxygen and water

Abstract

The interaction of defect-rich nanocrystalline indium oxide films, which have previously shown to exhibit excellent ozone sensing properties, with O-3, O-2, and H2O molecules is investigated using ultra-violet and X-ray photoelectron spectroscopy. The investigated samples are grown by metalorganic chemical vapor deposition at low temperatures resulting in high oxygen deficiency and high defect density. The ozone-induced surface oxidation and UV-induced photoreduction mechanisms of the ozone sensor active material are evaluated with respect to surface stoichiometry and electronic properties including adsorbate features, band bending and surface dipole formation. A strong interaction with ozone and water is found, whereas the interaction with O-2 is relatively weak. In all cases the interaction results in the same negatively charged oxygen adsorbate species. which can either be removed by UV light or by annealing resulting in the capability of these films to be used in reversible adsorption induced oxidation and UV/thermal reduction cycles

Towards Understanding the Cross‐Sensitivity of In2O3 Based Ozone Sensors: Effects of O3, O2 and H2O Adsorption at In2O3(111) Surfaces

“…Due to the high electronegativity of oxygen atoms, electrons are extracted from the SEAL and localized by either forming O − or O 2− species at the surface (see also Ref. ). Water could possibly dissociate to …”

“…Wang et al analyzed the sensitivity of metal‐organic chemical vapor deposition (MOCVD) grown In 2 O 3 nanoparticle films toward ozone in humid air and observed a decreased response toward O 3 for increasing humidity, which can be calibrated by an integrated humidity sensor. Recent studies on the gas interaction of nanocrystalline, defect‐rich In 2 O 3 surfaces observe the attachment of the same adsorbate species during ozone, oxygen, or water adsorption, which might be O − . Korotcenkov et al analyzed the influence of grain size and humidity on the sensor response of In 2 O 3 and SnO 2 based conductometric gas sensors.…”

Resolving the Structure of a Well-Ordered Hydroxyl Overlayer on In2O3(111): Nanomanipulation and Theory

“…After water/air exposure, the new peak at 532–532.5 eV was variably assigned to hydroxyl groups at the surface, “water-related species”, and physisorbed oxygen. The different interpretations might be due to the variety of samples used, including single crystals and (un)­doped thin films as well as nanoparticles and powders. − …”

Single-Atom (Iron-Based) Catalysts: Synthesis and Applications

“…This can be solved either by selectively recovering these ozone molecules using adsorption mechanisms with various surfaces or using ozone itself for VOC degradation by SAC catalysts. In this context, Krischok and co-workers studied the interaction of indium oxide nanoparticles with ozone . The interaction of ozone was found to be stronger than oxygen molecules, which is due to the oxygen deficiency on the catalyst surface.…”

“…The interaction of ozone was found to be stronger than oxygen molecules, which is due to the oxygen deficiency on the catalyst surface. Such oxygen-deficient materials may be a better option to recover ground-level ozone molecules as recovered ozone can be used further for the organic transformations. , VOCs dissolved in water, including formaldehyde, have been a lingering issue, and the removal of these VOCs from water streams is a great challenge. As we have seen, SACs display excellent stability and remarkable activity for electrocatalytic applications, and these same electrocatalysis setups can be used for VOC degradation.…”