Also, it is difficult to believe less than monolayer of Pt atoms show both metallic Pt(0) and Pt(2+) states in XPS spectra of Pt-Pd/C catalyst. It may have only one of the states. If Pt(2+) does exist, O 1s spectra must have its corresponding component peak at ~532.2 eV, so has to be included. When we calibrate XPS data with adventitious carbon, usually 284.8 or 250.0 eV is applied. What they used is 284.6 eV, which is a little bit lower than them, but made their Pt peak positions (71.25 and 72.86 eV) closer to 71.1 and 72.7 eV values for Pt metal and Pt(OH)2. It may be ok, but the spin-orbit splitting value has to be maintained during the deconvolution process. The value for Pt 4f7/2 -4f5/2 is 3.33 eV, but none of them matched. |