## 5 Conclusions  
This work presents a comprehensive study by physicochemical methods, including X-ray photoelectron spectroscopy, of the Pt/TiO\({}_{2}\) catalysts prepared on the basis of a standard commercial TiO\({}_{2}\)-P25 support and on a TiO\({}_{2}\) support synthesized using a pulsed laser ablation in liquid (PLA). The TiO\({}_{2}\) support synthesized by the PLA method contains rutile, brookite, and anatase phases with different particle sizes. Smaller particles of the rutile and brookite phases are distributed over the surface of the larger particles of anatase TiO\({}_{2}\). The Pt/TiO\({}_{2}\)-PLA catalyst obtained by impregnation of the PLA-support showed enhanced thermal stability compared to the catalyst based on the commercial P25 support. After calcination of the Pt/TiO\({}_{2}\)-PLA catalyst at 800 \({}^{\circ}\)C, the anatase phase is unambiguously detected by X-ray diffraction and Raman spectroscopy in contrast to the Pt/TiO\({}_{2}\)-P25 catalyst, in which the anatase phase completely transforms to rutile. HRTEM shows that the Pt/TiO\({}_{2}\)-PLA-400 catalyst contains platinum particles with an average size of 1.4 nm. The distribution of Pt particles over the surface of the support is not uniform. Particles preferentially localize at the interblock boundaries of the support and partially agglomerate. Larger particles are fixed mainly on the rutile surface, in contrast to the Pt/TiO\({}_{2}\)-P25 sample, in which platinum is uniformly distributed over the entire surface of the support. The states of the components of the catalysts were analyzed using the XPS after calcination in air at various temperatures and after exposure to the reaction medium. Annealing of the conventional Pt/TiO\({}_{2}\)-P25 catalyst at 400 \({}^{\circ}\)C leads to the formation of oxidized platinum structures PtO and PtO\({}_{2}\). In the Pt/TiO\({}_{2}\)-PLA-400 catalyst the oxidation state of platinum is lower due to the stronger interaction of the PtO\({}_{x}\) clusters (x \(<\) 1) with the support. The formation of Pt-O-Ti structures is confirmed by EXAFS data. This fact is also confirmed by TPR-H\({}_{2}\) experiments, which showed the presence of a single reactive state of oxygen in the Pt/TiO\({}_{2}\)-PLA-400 sample, in contrast to the two forms of oxygen in the Pt/TiO\({}_{2}\)-P25-400 catalyst. The Pt4f spectra of the samples after reaction show the residual form of Pt\({}^{2+}\) and the metallic form of platinum with a negative shift of the Pt4f doublet relative to the value typical for the bulk Pt metal. It was interpreted as the formation of Pt\({}^{8-}\) states. Calcination at 600 and 800 \({}^{\circ}\)C resulted in decomposition of the oxidic Pt structures and sintering of the support particles. These processes are more pronounced for the catalyst prepared with the commercial P25 support, apparently due to the sintering and recrystallization of anatase particles. The catalytic properties of the samples were studied in the ammonia oxidation reaction. The Pt/Ti-P25-400 catalyst demonstrates higher NH\({}_{3}\) conversion at low temperatures in the first catalytic NH\({}_{3}\)+O\({}_{2}\) cycle, however, the subsequent cycle suppresses this low-temperature activity. Unlike the conventional Pt/Ti-P25 catalyst, the Pt/Ti-PLA catalyst shows high stability in all cycles of the temperature-programmed reaction, with a significantly higher selectivity for the N\({}_{2}\) product in a wide temperature range of 200-400 \({}^{\circ}\)C.  
Thus, it has been shown that the use of the pulsed laser ablation for the synthesis of the TiO\({}_{2}\) support can provide significant advantages in comparison with the standard TiO\({}_{2}\)-P25 support. These include increased thermal stability of the crystalline phases of the support and the lower charge state of active component due to the stronger interaction with the support. All these factors play an important role for the practical application of ammonia slip catalysts.