## 3 Results and Discussion
### Photocatalytic Efficiency  
The evaluation of photocatalytic efficiency for prepared AgNP/TiO\({}_{2}\) was done by the photodegradation of RhB solution under UV-C light irradiation. The RhB solution has the highest light absorbance at ~550-560 nm wavelength. Thus, this range was taken during the analysis. The light absorbance at 0 min attributes to the initial concentration of RhB (\(C_{0}\)/\(C_{0}\)), and the latter light absorbance attributes to the decrease in concentration after 20, 40, 60, and 80 min and is considered as \(C_{1}\)/\(C_{0}\), \(C_{2}\)/\(C_{0}\), \(C_{3}\)/\(C_{0}\), \(C_{4}\)/\(C_{0}\) respectively. The 50% decolorization of RhB was reached in ~50 min for AgNP/TiO\({}_{2}\), where an average AgNPs diameter was ~38 nm (Figure 6a), whereas the 50% decolorization of RhB by using the AgNP/TiO\({}_{2}\) with an average AgNPs diameter of 27 and 82 nm was reached in ~59 min and 58 min, respectively. Considering the TiO\({}_{2}\) as a stand-alone photocatalyst, the same result was reached after ~78 min, and for RhB (without the photocatalyst) only after 100 min. The LSPR effect can be observed in the transmittance spectra of AgNP/TiO\({}_{2}\) structures (Figure 5). The transmittance of visible light reached minimum values in the 550-650 nm range. It can be seen that the LSPR effect increased with the size of AgNPs on the surface of TiO\({}_{2}\) thin films. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**The Initial Thickness of Ag Thin Films (\(h_{Ag}\))** & **5 nm** & **7.5 nm** & **10 nm** \\ \hline Average area (\(A\)), nm\({}^{2}\) & 705 & 1324 & 6003 \\ \hline Average diameter (\(D_{A}\)), nm & 27 & 38 & 82 \\ \hline Density (\(n\)), \(\upmu\)m\({}^{-2}\) & 398 & 229 & 42 \\ \hline Coverage (\(SC\)), \% & 28 & 30 & 23 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The parameters of AgNPs on the surface of TiO\({}_{2}\). Figure 4: XRD of (**a**) Ag/TiO\({}_{2}\) structures (before SSD) and (**b**) AgNP/TiO\({}_{2}\) structures (after SSD). The degradation efficiency was evaluated after 60 min of UV light irradiation (Figure 6b). Clear dependence between AgNPs diameter and degradation efficiency was not observed. The peak value of photocatalytic efficiency was found for AgNP/TiO\({}_{2}\), where an average AgNPs diameter was \(\sim\)38 nm (\(k_{38}\) = 0.017 min\({}^{-1}\), \(D_{\mathit{eff\_38}}\) = 63.5%), whereas degradation rate constant and degradation efficiency for AgNPs of \(<\)\(d_{Ag}\)\(>\) = 27 nm and \(<\)\(d_{Ag}\)\(>\) = 82 nm were \(k_{27}\) = 0.012 min\({}^{-1}\), \(D_{\mathit{eff\_27}}\) = 51.2% and \(k_{82}\) = 0.011 min\({}^{-1}\), \(D_{\mathit{eff\_82}}\) = 52.1%, respectively. It was also found that photocatalytic efficiency of AgNP/TiO\({}_{2}\), where \(<\)\(d_{Ag}\)\(>\) = 38 nm (\(k_{38}\) = 0.017 min\({}^{-1}\), \(D_{\mathit{eff\_38}}\) = 63.5%) was 1.7 times higher than photocatalytic efficiency of pure TiO\({}_{2}\) thin films (\(k_{TiO2}\) = 0.008 min\({}^{-1}\), \(D_{\mathit{eff\_TiO2}}\) = 36.3%). Comparison of the results with the literature is complicated due to different experimental conditions, i.e., different initial concentrations of RhB, different active areas of photocatalysts, different light sources, irradiance, etc. Therefore, the results obtained by other authors are contradictory. For example, the 50% decolorization of RhB was reached after \(\sim\)30 min for anatase thin films by [PERSON] et al. and for TiO\({}_{2}\)/\(\beta\)-SiC foam by [PERSON] et al., while [PERSON] et al. reached 50% decolorization of RhB for TiO\({}_{2}\) nanorods only after 4 h [42; 43; 44]. Nevertheless, our results suggest that AgNPs can enhance the photocatalytic efficiency of TiO\({}_{2}\) thin films. In addition, they are similar to [PERSON] et. al. results [45]. Authors also found that TiO\({}_{2}\) thin films decorated with AgNPs (\(<\)50 nm) have 1.7 times higher photocatalytic efficiency than bare TiO\({}_{2}\) thin films. Figure 5: (**a**) Transmittance spectra of AgNP/TiO\({}_{2}\) structures and (**b**) LSPR dependency on \(<\)\(d_{Ag}\)\(>\).