I have taken the XPS of TiO2 and Mn-doped TiO2 and found a systematic shifting of all peaks like C1s in pure is about 284.8 but in 2%Mn doped it comes to around 289.4 eV etc.
What is the relevance of C correction in XPS analysis?
In XPS spectra of materials, all binding energies should be corrected using a standard. Usually, carbon element with binding energy of C 1s = 284.6 eV is used as an internal standard. You should shift the binding energies of your samples based on this value. For example, please refer to the attached paper.