Photocatalytic concrete for NOx abatement: Supported TiO₂ efficiencies and impacts

The potential of TiO₂-based photocatalysts in mitigating the effects of environmental pollutants is evident in the scientific literature but the large-scale implementation of photocatalytic concretes still appears limited, despite the current global concerns over urban NOx pollution. Improvements in cost-effectiveness are required to enhance the case for a photocatalyst-modified infrastructure and this must address catalyst efficiency, catalyst loading and performance durability. This paper compares photocatalytic efficiencies of supported TiO₂ on mortar surfaces with the more conventional TiO₂ dispersed in mortar. The influences of environmental conditions, such as NO concentration and flow rate, UVA light intensity and relative humidity, on photocatalytic performance are also investigated using photonic efficiency as an indicator. The supported TiO₂ shows greater degradation of NOx (De-NOx), at about 9 times higher than TiO₂ powder dispersed in the mortar, ca. 150 times higher utilization efficiency, than that of TiO₂ in traditional photocatalytic mortar (with 5% loading).