I made defective TiO2 with Oxygen vacancies and I noticed the O 1s peak shifts to lower binding energy compared to the pristine TiO2. How Can I explain that?
Fereshteh Rezvani Do you have a graph you can show? I've done quite a bit of work on O1s photoelectron spectra.
-Adam
https://www.researchgate.net/post/What_does_a_shift_in_XPS_peaks_mean
https://www.researchgate.net/post/What-does-peak-shifting-and-intensity-signifies-in-XPS-spectrum
I don't think the assignment you have made is correct. Some years ago we detected these oxygen vacancies, but they were associated with binding energies greater than those of oxygen in the framework. I am sending you this paper so you can see it.
https://www.researchgate.net/post/What-does-peak-shifting-and-intensity-signifies-in-XPS-spectrum
https://www.researchgate.net/post/What_does_a_shift_in_XPS_peaks_mean
https://www.eag.com/resources/appnotes/xps-chemical-shift-and-valence/
For TiO2, https://pages.jh.edu/chem/fairbr/surfacelab/xps.html
You have to address these points:
1. Does the Ti2p also shift? If so its a charging issue - recalibrate your data to the Ti2p3/2 peak at 458.5 eV
2. How does XPS detect oxygen vacancies? A vacancy WILL NOT give a O1s signal, instead the lattice oxide peak will broaden - anyone assigning a high binding energy peak is an oxygen vacnacy is just wrong
(see for example: Article On the wrong assignment of the XPS O1s signal at 531-532 eV ...
3. If the samples are air handled, then you are very unlikely to have oxygen vacancies anyway as oxygen/water from the atmosphere will fill these gaps
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