Effect of Sm³⁺ on the Structural Properties and Photocatalytical Performance of TiO₂&Au Nanocomposites

The synthesis of TiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>&Au/Sm particles with gold content of 2 and $4 \mathrm{wt}. \%$ and samarium $0.2 \mathrm{wt}. \%$ was carried out by the chemical precipitation of a TTIP solution in the presence of $\mathbf{S m}^{3+}$ and $\mathbf{A u}^{3+}$ cations. The CSR of nanopowders was $18-20 \mathrm{~nm}$. It was shown that gold is included in the structure of the composite, which leaded to an increase in the parameters of the anatase crystal lattice. The presence of samarium in the structure of the composite was confirmed by EDS and PL methods. The obtained structures have been shown high sorption activity to cationic dyes (Methylene Blue and Rhodamine B) and lower - to anionic ones, in particular, Orange G. It is shown that under the influence of UV irradiation, the solutions undergo discoloration, which is accompanied by the destruction of dye’s molecules, which is confirmed by the hypsochromic shift of the characteristic maximum in the UV-VL spectra. The series OG (46.7 %) < MO (89.2%) < MB (96.0%) < RhB (98.5%) for TiO2&Au/Sm particles ([Au] = 2 wt.%, [Sm] = 0.2 wt.%) and MO (22.6 %) < RhB (24.1 %) < OG (41.5 %)< MB (98.6 %) for TiO2&Au/Sm ([Au] = 4 wt.%, [Sm] = 0.2 wt.%) particles were found according to the intensity of discoloration of the dye’s solutions. The difference in the course of the photocatalytic process can be related to the PZC (point of zero charge) of the composite particles, which is 7.01 7.01 ([Au] = 2 wt.%) and 9.25 ([Au] = 2 wt.%)..