**4. Conclusions**

In summary, Ag-modified TiO<sup>2</sup> thin films were successfully anchored on bamboo material through a facile hydrothermal process, followed by an Ag mirror reaction for photoactivated antifungal coating. Upon decorating Ag NPs on anatase TiO<sup>2</sup> thin films, the composite films showed an enlarged optical response region and improved quantum efficiency. The antifungal test results show that the Ag/TiO<sup>2</sup> composite films grown on the bamboo surface produced a synergistic antifungal mechanism compared with pure Ag NPs or anatase TiO<sup>2</sup> film under both light and dark conditions. However, the antifungal activity of Ag/TiO<sup>2</sup> composite films under visible light is superior to that in the dark, owing to the transfer of photoexcited electrons from Ag to TiO2, their trapping on TiO<sup>2</sup> under visible light illumination, and their release in the dark, which could give this photocatalyst a catalytic memory for producing •O<sup>2</sup> <sup>−</sup>and •OH radicals in the absence of light illumination. We believe that this discovery could open a door for the continuous removal of indoor air pollutants such as VOCs, bacteria, and fungus in the day and night time.

**Supplementary Materials:** The following are available online at https://www.mdpi.com/article/10 .3390/jof7080592/s1, Figure S1: Antifungal test. Figure S2: EDS spectrum of ATB-10. Inset images are corresponding elemental mapping results. Figure S3: XPS survey spectra of (a) original bamboo, (b) TB, and (c) ATB-10. Figure S4: SEM micrograph for a cross-sectional profile of the TiO<sup>2</sup> thin film on bamboo substrate. Figure S5: XRD pattern of the as-prepared TB. Figure S6: High-resolution XPS spectrum of F 1s.

**Author Contributions:** Conceptualization, J.L. and J.W.; methodology, J.L. and Y.C.; software, J.L. and R.M.; formal analysis, Z.W.; investigation, S.H. and R.B.; resources, J.L.; writing—original draft preparation, J.L., R.M. and J.W.; writing—review and editing, J.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** The work was financially supported by the Project of Forestry Science and Technology of the Zhejiang Province (2021SY13), Zhejiang Provincial Natural Science Foundation of China (LQ20C160002), and Fundamental Research Funds for the Central Non-profit Research Institution of CAF (CAFYBB2017MA023).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** The authors would like to thank Teacher Yang from Shiyanjia Lab (http://www. shiyanjia.com, accessed on 28 May 2021) for the ESR analysis.

**Conflicts of Interest:** There are no conflicts to declare.

### **References**

