Photocatalytic NOx Removal in Bismuth-Oxyhalide (BiOX, X = I, Cl) Cement-Based Materials Exposed to Outdoor Conditions

Cement-based materials modified with 3D BiOX (X = I, Cl) microspheres at different percentages (1, 5 and 10% by weight of the cement binder) were prepared to investigate durability photocatalytic NOx removal under outdoor conditions. Weathering—corresponding a period 13 months outdoors—was studied in terms NO efficiency visible UVA light irradiation for BiOI BiOCl mortars, respectively. Following this period, samples protected from environment four years, selectivity nitrates assessed. mortar initially photocatalytically active; performance increased as content increased. There was good photocatalyst dispersion, compressive strength not significantly impacted. The mortars had nearly completely lost their activity after years casting, whereas containing maintained about 7% initial performance. results suggest that deactivation is due surface dirt accumulation oxidation on rather than carbonation. An internal self-deactivation mechanism affects matrix has also been postulated.