Synergistic Effect of Combined Polymorphs Anatase-Rutile Nano-Modified Lightweight Concrete on Photocatalytic Reduction of NOx, Self-Cleaning Performance, and Antimicrobial Properties

Anatase, one of the polymorphs of titanium dioxide (TiO2), has become the most widely used semiconductor for photocatalytic materials due to its chemical and physical properties. However, researchers have been studying the use of alternative materials (e.g., ZnO, N-doped, and C-doped TiO2) to improve the photocatalytic activity of cementitious materials. In this paper, we propose a modification of lightweight concrete by introducing mixed phases of titanium dioxide-anatase and rutile-to enhance its photocatalytic performance. The efficiency of NOx degradation of nano TiO2-modified concrete, its self-cleaning performance, and its antimicrobial properties were studied. The photocatalytic activity of lightweight concrete without TiO2 and concrete with the addition of anatase, rutile, and anatase-rutile was compared. The results show that modifying the samples by adding a mixture of anatase and rutile (2.5 wt % A + 2.5 wt % R) significantly improved the photocatalytic performance of lightweight concrete.