SiO2/TiO2 composite powders deposited on cement-based materials: Rhodamine B removal and the bonding mechanism

For surface functionalization of cement-based materials with photocatalytic properties, weak adhesion between photocatalysis and matrix worsens these properties and results in poor weathering resistance in outdoor environments. To overcome these problems, in this study, two SiO 2 /TiO 2 composites, with different deposited densities of TiO 2 nanoparticles on a SiO 2 sphere, were prepared and used for surface coating of cement-based materials. The two composites show different efficiencies. The photocatalytic results show that the coated cement pastes exhibited excellent rhodamine B-removal efficiency before and after curing and accelerated weathering processes, indicating that SiO 2 in the system has   a   crucial   effect as a ‘glue’ preventing the release of TiO 2 . The bonding mechanism was revealed by the reaction of the samples and main components and hydration products (such as CH, C-S-H and C 3 S).