Strategies to improve the antimicrobial properties of metal-oxide based photocatalytic coating: A review

As surface contamination has become a major public concern, extensive research into antimicrobial coatings has been conducted as potential long-term solutions against health-associated infections (HAIs). These coatings are intended to keep bacteria and germs from growing and spreading on surfaces such as walls, doors, and high-touch points. Metal oxides (MOs) and MO-based semiconductors have received growing interest from both academic and industrial sectors as photocatalytic coating materials. The ability of these oxide materials to utilize energy in the UV/visible light range, as well as their relative ease of synthesis, low cost, and overall high surface area, make them stand out. Furthermore, because most metal oxide semiconductors are non-toxic, they are suitable for various antimicrobial applications, including biological contamination and self-cleaning surfaces. However, issues with retaining a stable enough and less leachable coating while also being effective in the elimination of microbes have yet to be resolved. This review begins with a general discussion of antimicrobial agents, MO-based semiconductor material properties and the application of common MOs as a photocatalytic antimicrobial coating such as TiO2, Cu2O, and ZnO. The challenges of photocatalytic antimicrobial coatings are discussed, as well as strategies for improving photocatalytic antimicrobial performance, in two different perspectives; photocatalyst development and coating factors. The major strategic techniques in photocatalyst development perspectives for improving photocatalytic performance are doping, synthesis method, and heterojunction formation. Meanwhile, post-treatment and the use of binders and surfactants are the strategies for improving coating performance and durability from the point of view of coating factors. Finally, coating methods are discussed to help the reader choose a suitable coating method for producing high performance photocatalytic antimicrobial coating.