Photocatalytic cement-based materials: Comparison of nitrogen oxides and toluene removal potentials and evaluation of self-cleaning performance

Using cement-based building materials as a matrix for nano-photocatalysts is an important development for the large scale application of photocatalytic technologies. Air pollution mitigation and self-cleaning surface are two major applications of photocatalytic building materials. In this study, a comparison was made to evaluate the performance of TiO 2 modified concrete surface layers for NO x and VOC degradation. The self-cleaning performance of TiO 2 modified self-compacting mortars (SCM) developed for decorative applications was also evaluated. The results show that the photocatalytic conversion of toluene by the TiO 2 modified surface layer was not detected, although NO x could be effectively removed under the same conditions. The presence of toluene did not influence the NO x removal process. TiO 2 modified SCM were found to be effective in the discoloration of rhodamine B under UV and strong halogen light irradiation. The level of adsorption of the air contaminants onto the active sites of the cement-TiO 2 composite was identified to be the key factor determining the subsequent photocatalytic efficiency.