## 3 Results
### XPS Analysis
#### 3.5.2 Analysis of Pt4f and Ti3s Spectral Region  
In order to obtain the correct data on the state of platinum from the analysis of the Pt4f spectra it was necessary to subtract the contribution of the lines from the TiO\({}_{2}\) support within the Pt4f spectral region. The Ti3s line is characterized by the presence of a satellite structure/background of scattered electrons in the range of 70-80 eV with a maximum intensity in at 75.7 eV (Figure 7a). Despite the low intensity of the Ti3s line and even lower intensity of the satellite, their impact can significantly complicate analysis of the Pt4f spectra for Pt/TiO\({}_{2}\) samples with low platinum loading. To obtain a corrected Pt4f spectrum, the background line recorded for a pure TiO\({}_{2}\) support was subtracted from the experimental spectrum of Pt/TiO\({}_{2}\) sample. The intensity of a given background line should be normalized by the Ti3s line recorded for the catalyst and pure support. However, the Ti3s line has low intensity and, in order to prevent surface reduction by long X-ray exposure, the line of the subtracted background was normalized to the intense of Ti2p line. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Element**} & \multirow{2}{*}{**Binding**} & \multirow{2}{*}{**Interpretation**} & \multicolumn{3}{c}{**Pt/Ti-PLA**} & \multicolumn{3}{c}{**Pt/Ti-P25**} \\ \cline{3-8}  & & & **400 °C** & **600 °C** & **800 °C** & **400 °C** & **600 °C** & **800 °C** \\ \hline \multirow{2}{*}{**Pt4f**} & & & 0.58 & 0.16 & 0.20 & 0.41 & 0.11 & 0.15 \\ \cline{2-8}  & 70.6–70.9 & Pt0 & 0 & 0.06 & 0.15 & 0 & 0.03 & 0.11 \\ \cline{2-8}  & 71.7–73.1 & Pt2+ & 0.28 & 0 & 0 & 0.26 & 0.02 & 0.04 \\ \cline{2-8}  & 73.7–74.9 & Pt4+ & 0.30 & 0.10 & 0.05 & 0.15 & 0.06 & 0.00 \\ \cline{2-8}
**Pt/Ti** & & & 0.028 & 0.008 & 0.010 & 0.021 & 0.005 & 0.010 \\ \hline \multirow{2}{*}{**Ti2p**} & 458.6 & Ti4+ & 21.0 & 20.3 & 18.2 & 20.3 & 20.4 & 14.7 \\ \hline \multirow{2}{*}{**O1s**} & & & 57.2 & 55.3 & 56.0 & 54.6 & 55.6 & 44.3 \\ \cline{2-8}  & 529.9–530.0 & Ti-O\({}_{lattice}\) & 48.8 & 46.5 & 45.0 & 46.0 & 45.1 & 32.5 \\ \cline{2-8}  & 531.5–531.7 & Ti-O\({}_{ads}\) & 8.4 & 8.8 & 11.0 & 8.6 & 10.5 & 11.8 \\ \hline \multirow{2}{*}{**Cls**} & & & 21.2 & 24.2 & 25.6 & 24.7 & 23.9 & 40.8 \\ \cline{2-8}  & 285.1–285.2 & C-C. C-H & 19.3 & 21.5 & 23.9 & 22.5 & 20.5 & 38.5 \\ \cline{2-8}  & 288.3–288.6 & CO\({}_{x}\) & 1.9 & 2.7 & 1.7 & 2.2 & 3.4 & 2.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Charge states and surface concentrations (atomic %) of the elements by X-ray photoelectron spectroscopy (XPS). Figure 7: (**a**) The XPS spectrum of Ti3s satellite for pure TiO\({}_{2}\) support; (**b**) the experimental XPS spectrum of the Pt4f region for Pt/TiO\({}_{2}\) catalyst (**c**) the Pt4f spectrum after Ti3s satellite subtraction; (**d**) the curve-fitted Pt4f spectrum. Figure 7b,c illustrates that the Ti3s satellite, with a maximum at 75.7 eV, can influence the platinum line shape, provided that the intensity of platinum line is low either due to low dispersion or loading of platinum. Even for relatively high loading of platinum (about 2%), the integral line shape is distorted and the Pt4f5/2 component becomes more intense than Pt4f7/2 which has no physical meaning. Thus, the presence of the Ti3s satellite line should be taken into account when analyzing Pt/TiO2 catalysts by XPS. Using the described procedure, corrected Pt4f spectra were obtained for all samples. Concentrations of all elements on the surface with contributions of the individual oxidation states were estimated from the XPS data (Table 3). The increase of the calcination temperature leads to the decrease of the total platinum amount observed by XPS. As XPS is a surface sensitive technique, this decrease might be caused by sintering of platinum in accordance with the XRD data (Table 1). The sintering of platinum is accompanied by TiO2 particle growth. At 800 \({}^{\circ}\)C, the decrease in the TiO2 surface is more pronounced compared to the Pt surface.