The superiority of TiO2 hollow microspheres over nanoparticles upon integration into a coating formulation for VOC removal

Heterogeneous photocatalysis is a promising technology for the abatement of pollutants in the air. Practical application of this technology requires the incorporation of the photocatalyst into a coating formulation. The coating can subsequently be applied on surfaces with a large geometric area, promoting various catalytic reactions. Photocatalysts, such as TiO2, appear to be most active in the form of nanoparticles. However, there is a rising concern regarding the adverse health effects of the nano‐sized particles. In this study, we investigate the photocatalytic oxidation of isopropanol, a common VOC, and demonstrate that a water‐based acrylic coating containing TiO2 micrometer‐sized hollow spheres can outperform a nanoparticle‐based coating by a factor of 10 in the rate of isopropanol removal. The porous shell structure of TiO2 hollow microspheres enables a three‐dimensional surface porosity within the coating film, thereby enhancing the access to the active catalytic surface. Our findings underscore the importance of the catalyst morphology for practical applications of photocatalytic materials when integrated into a coating formulation. Photocatalytic TiO2 pigments can be incorporated into a coating formulation to facilitate the elimination of VOC molecules in the air via a photocatalytic oxidation process. Altering the morphology of TiO2 particles to obtain a hollow and porous structure is a promising approach in enhancing the activity of these functional coatings for the photocatalytic oxidation of isopropanol.