![casa xps peak fitting casa xps peak fitting](http://3.bp.blogspot.com/_By0IrJU9HPE/Se3Q1UTGcsI/AAAAAAAAA0M/5izTXczFgns/s400/tungsten.jpg)
These articles have successfully advanced insights into the changes in the lattice and surface mechanisms of specific types of TiO 2 crystal faces yet, more understandings of the surface characteristics of commercially available TiO 2 powder are needed to elucidate unique observations of actual applications under the ambient environment, such as disinfection by photocatalytic TiO 2 powder in the dark. Most findings were summarized by Hendersen, with the details given in the references therein 1, 2, 3. To date, abundant experimental studies have reported atomic-level observations of TiO 2 surfaces as thin films or single crystals using various tools, such as scanning tunneling microscopy (STM) and electron paramagnetic resonance (EPR). Titanium dioxide (TiO 2) is one of the most commonly used photocatalysts with wide modifications for numerous applications. The persistent peroxides on the powder further explain previously observed prolonged oxidation capability of TiO 2 powder without light irradiation. Two new surface peaks at 1.7–1.8 and 4.0–4.2 eV above lattice oxygen are designated as peroxides (OOH/H 2O 2) and H 2O 2 dissolved in water, respectively. In the dark, the continual supply of both water vapor and oxygen is the key factor retaining the activated state of the TiO 2 powder for a time period.
![casa xps peak fitting casa xps peak fitting](https://i.ytimg.com/vi/-nCchGGAxGE/maxresdefault.jpg)
![casa xps peak fitting casa xps peak fitting](https://i.ytimg.com/vi/R-o-5NBKLZc/maxresdefault.jpg)
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. This enables novel and complementary approach to characterize reactivity of TiO 2 powder. Under all the study environments, the bridging hydroxyl (OH br) and terminal hydroxyl (OH t) are identified at 1.1–1.3 eV and 2.1–2.3 eV above lattice oxygen, respectively. Both Ti 2p and O 1s spectra show hysteresis through the experimental course. 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 TiO 2 powder using near-ambient-pressure X-ray photoelectron spectroscopy (XPS).