In order to relate photoemission and electrochemical data, you need to allign the XPS reference binding energy scale, and the electrochemical energy scale. Usually the binding energy EB in XPS/UPS is referenced to the Fermi level EF with EB EF = 0eV and the redox scale is referenced to the electrochemical potential of the standard hydrogene electrode SHE. In order to line up the two scales, you need a common reference which is the vacuum level Evac. Now with UPS you can measure the work function Phi of a material which tells you how far below Evac the Fermi level is and the work function or the absolute electrode potential of SHE is recommended with 4.44eV by IUPAC, so SHE is 4.44eV below Evac.

Flat band gives you the amount of band-bending caused by the Fermi level pinning at the Schottky interface. Band-gap/band-edge positions are, on the other hand, inherent properties of the semiconductor. While the conduction band position w.r. to the vacuum level gives you the electron affinity, I really don't see much you can pull up with what you have.

Thank you Sabih and Pratheep. I will check.

In order to relate photoemission and electrochemical data, you need to allign the XPS reference binding energy scale, and the electrochemical energy scale. Usually the binding energy EB in XPS/UPS is referenced to the Fermi level EF with EB EF = 0eV and the redox scale is referenced to the electrochemical potential of the standard hydrogene electrode SHE. In order to line up the two scales, you need a common reference which is the vacuum level Evac. Now with UPS you can measure the work function Phi of a material which tells you how far below Evac the Fermi level is and the work function or the absolute electrode potential of SHE is recommended with 4.44eV by IUPAC, so SHE is 4.44eV below Evac.

you can find your answer at the attached files

Dear Preethi Kuppusamy,

can you tell me how you calculated valence band edge from XPS?

thanks in advance