Characterization of photocatalytic TiO2 powder under varied environments using near ambient pressure X-ray photoelectron spectroscopy
| Autor: | Minghui Liu, Paulo J.M. Monteiro, Min-Hong Zhang, Liya E. Yu, Pierre-Adrien Itty, Padmaja Krishnan, Vanessa Rheinheimer, Zhi Liu |
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| Rok vydání: | 2017 |
| Předmět: |
Multidisciplinary
Materials science Analytical chemistry chemistry.chemical_element 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Oxygen Spectral line 0104 chemical sciences Other Physical Sciences X-ray photoelectron spectroscopy chemistry Photocatalysis Molecule Biochemistry and Cell Biology Irradiation 0210 nano-technology Water vapor Ambient pressure |
| Zdroj: | Scientific reports, vol 7, iss 1 |
| ISSN: | 2045-2322 |
| Popis: | Consecutive eight study phases under the successive presence and absence of UV irradiation, water vapor, and oxygen were conducted to characterize surface changes in the photocatalytic TiO2 powder using near-ambient-pressure X-ray photoelectron spectroscopy (XPS). Both Ti 2p and O 1s spectra show hysteresis through the experimental course. Under all the study environments, the bridging hydroxyl (OHbr) and terminal hydroxyl (OHt) are identified at 1.1–1.3 eV and 2.1–2.3 eV above lattice oxygen, respectively. This enables novel and complementary approach to characterize reactivity of TiO2 powder. The dynamic behavior of surface-bound water molecules under each study environment is identified, while maintaining a constant distance of 1.3 eV from the position of water vapor. In the dark, the continual supply of both water vapor and oxygen is the key factor retaining the activated state of the TiO2 powder for a time period. Two new surface peaks at 1.7–1.8 and 4.0–4.2 eV above lattice oxygen are designated as peroxides (OOH/H2O2) and H2O2 dissolved in water, respectively. The persistent peroxides on the powder further explain previously observed prolonged oxidation capability of TiO2 powder without light irradiation. |
| Databáze: | OpenAIRE |
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