Photocatalytic activities and chemically-bonded mechanism of SiO2@ TiO2 nanocomposites coated cement-based materials

Photocatalytic technology has been studied in building materials, especially for the surface. However, the drawback of surface-treatment application is weak adhesion between coatings and the substrates resulting poor durability in outdoor environments. In the study, two SiO2@TiO2 core-shell nanocomposites were synthetized and coated cement-based materials, and the photocatalytic activity (rhodamine B removal efficiency) and surface modification/densification performances of coated cement-based materials were studied. The two samples have different deposited densities of TiO2 nanoparticles on each SiO2 nanosphere. Water adsorption rates of coated mortar measured at 270 min decreased by 17.8% when curing time was 28 days. Reaction experiments of SiO2@TiO2 nanocomposites and Ca(OH)(2) with different dosages were carried out to investigate the reaction mechanism. The formation of C-S-H gel was confirmed due to the pozzolanic reaction of samples and Ca(OH)(2). The coated cement pastes show excellent photocatalytic activity for rhodamine B removal.