The Role of Surface {010} Facets in Improving the NOx Depolluting Activity of TiO2 and Its Application on Building Materials

Abstract

Air pollution, a major health concern, necessitates innovative solutions such as TiO2-based photocatalytic building materials to combat its harmful effects. This study focuses on developing high-performance TiO2 photocatalysts for NOx removal in building applications, aiming to overcome the limitations of commercial TiO2. These photocatalysts were synthesized via a hydrothermal method, with parameters such as synthesis time and post-treatment investigated to optimize their properties. Hydrothermal synthesis yielded TiO2 nanoparticles with reduced aggregation and a high proportion of elongated particles with exposed {010} facets. This resulted in significantly enhanced photocatalytic activity compared to commercial P25 in methylene blue degradation and NOx depollution. Subsequently, the optimized hydrothermal TiO2 was successfully integrated into a silica sol–gel coating for application on building materials. The coated concrete demonstrated significantly higher NOx removal efficiency and lower NO2 release, achieving a 1.7-fold improvement in overall NOx removal and significantly higher depolluting effectiveness compared to its P25 counterpart. These findings highlight the potential of hydrothermally synthesized TiO2 with controlled morphology for the development of high-performance, environmentally friendly building materials with enhanced air purification capabilities.