Nanostructured TiO2-based photocatalysts can be integrated to building materials for multifunction such as air purification.It is crucial for this purpose to develop highly efficient nanostructured photocatalysts with excellent photostability and nanotechnology for the integration.In this abstract, we introduce several progresses in this area.We develop a novel strategy to significantly improve the photocatalytic efficiency of TiO2 nanocrystals by tuning their bulk/surface defects.