TiO₂-based Protective Coatings for Buildings and Monuments

Owing to the self-cleaning, de-polluting, and antibiofouling properties, the development of TiO₂ -based materials has enabled the application of multifunctional protective coatings for buildings and monuments. This chapter begins with a brief introduction to the basic principles of stone degradation and protection. By focusing on protective coatings, the major research directions (e.g., TiO₂ dispersions and/or nanocomposites, hydrophilic, and/or hydrophobic) in the field are categorized. The advancements in coating preparation and application are reviewed. The synthesis and/or formulation, characterization, and performance evaluation in the lab and in situ are described. Some practical case studies are also presented. Besides, the essential working mechanisms underlying the protective performance are discussed. Last, prospects in the field are outlined. These findings indicate that, to scale up the preparation and application, in-depth studies are required in various aspects: (i) understanding the physicochemical phenomena occurring at the coating-substrate interfaces and (ii) achieving satisfactory equilibrium between the photoactivity and stability of coatings.