## 3 Results
The results suggest that the photocatalytic effect is the best when the sputtering power is 5 W and the sputtering time of Ag is 50 s. Figure 5b shows UV-Vis absorption spectra of MO solution with an initial concentration of 10 mg L\({}^{-1}\) under different illumination times during the photocatalytic degradation of MO using Ag/TiO\({}_{2}\)-5 W-50 s in pure MO solution. Figure 5c shows the degradation rate of MO solution via Ag/TiO\({}_{2}\) modified using Ag with different sputtering power and sputtering times of Ag in pure MO solution. It demonstrates that the degradation rate of MO solution using Ag/TiO\({}_{2}\)-5 W-50 s can reach 100% within 55 min. The results also indicate that although the redshift of Ag/TiO\({}_{2}\)-5 W-50 s is not as significant as that of Ag/TiO\({}_{2}\) using the high-power and long-time sputtering of Ag, small particles of Ag can help to improve the separation of photogenerated electron-hole pairs, thereby enhancing the degradation effect. The main reason for this phenomenon may be (1) the interface between Ag nanoparticles deposited on the TiO\({}_{2}\) surface and TiO\({}_{2}\) nanoparticles, forming a Schottky barrier that enables the continuous migration and enrichment of photogenerated electrons to Ag particles, and facilitates the separation of electrons and holes, thus improving the photocatalytic activity [29; 30]; (2) the Ag nanoparticles on the TiO\({}_{2}\) surface, causing the electron cloud density on the TiO\({}_{2}\) surface to decrease, which facilitates the adsorption of O\({}_{2}\) on the (101) crystal surface of anatase TiO\({}_{2}\), allowing the photogenerated electrons to react with more O\({}_{2}\) to form reactive substances, such as -O\({}_{2}\)\({}^{-}\), -OH, etc., thereby further increasing the catalytic activity of the catalysts [27; 28]; (3) or that Ag/TiO\({}_{2}\)-5 W-50 s has a strong adsorption effect on organic compounds (e.g., MO) containing N and S functional groups, and in the oxygen-enriched state (O\({}_{2}\) adsorption from the crystal surface of anatase TiO\({}_{2}\)(101)), the connection between MO and TiO\({}_{2}\) is in the form of S-O bonds [31]. Figure 4: UV-Vis DRS of (**a**) TiO\({}_{2}\), (**b**) Ag/TiO\({}_{2}\)-5 W-100 s, Ag/TiO\({}_{2}\)-10 W-100 s, and Ag/TiO\({}_{2}\)-15 W-100 s photocatalysts; (**c**) Ag/TiO\({}_{2}\)-5 W-50 s, Ag/TiO\({}_{2}\)-5 W-100 s, and Ag/TiO\({}_{2}\)-5 W-150 s photocatalysts; Tauc plots obtained for (**d**) TiO\({}_{2}\) photocatalysts, (**e**) Ag/TiO\({}_{2}\)-5 W-100 s, Ag/TiO\({}_{2}\)-10 W-100 s, and Ag/TiO\({}_{2}\)-15 W-100 s photocatalysts; and (**f**) Ag/TiO\({}_{2}\)-5 W-50 s, Ag/TiO\({}_{2}\)-5 W-100 s, and Ag/TiO\({}_{2}\)-5 W-150 s photocatalysts. In keeping the experimental conditions unchanged, the recovered photocatalyst with the best degradation effect (Ag/TiO\({}_{2}\)-5 W-50 s films) was used to degrade MO. Figure 6 shows the photocatalytic effect of the recycled photocatalyst. Figure 6a shows UV-Vis absorption spectra of MO solution after different cycles of photocatalytic degradation in pure MO solution. The degradation rate of MO (C\({}_{0}\) = 10 mg L\({}^{-1}\)) using Ag/TiO\({}_{2}\)-5 W-50 s with different cycles in pure MO solution is shown in Figure 6b. It can be found that the degradation effect of the first time is the best, reaching 100% in only 55 min, and the degradation rate of the fourth cycle is 100%, but this takes 90 min. Although the final degradation rate can reach 100%, the degradation time extends significantly as the number of cycles increases. This occurrence is caused by some water-insoluble or intermediate water-insoluble products that have been adsorbed on the catalyst's surface, which affects the adsorption performance and absorbance of the catalyst and reduces the degradation effect [24]. In addition, Ag particles can be oxidized, leading to an increase in the recombination rate of photogenerated electron-hole pairs, reducing the utilization rate of photogenerated charge carriers [32; 33].