Photocatalytic nano-composite architectural lime mortar for degradation of urban pollutants under solar and visible (interior) light

[Display omitted] •Novel functionalised photocatalytic mortar-based nanocomposites are reported.•Commercial mortar with 1 and 5wt% Ag-doped TiO2 (1mol% Ag) nanoparticle additives.•Silver doping shifts band gap of titania NPs into visible light wavelengths.•Nano-additives have no significant effects on curing or colour or mortar.•Photocatalyst mortars: remove NOx min under sunlight, VOC removal under white light. Recent advances in nano-technology and nano-additives can give enhanced properties to natural hydraulic lime (NHL), creating a multifunctional material. We have prepared a novel nanocomposite, made of a commercial mortar with 1wt% and 5wt% added titania nanoparticles (NPs). These TiO2 NPs are themselves doped with 1mol% silver, to give the material enhanced photocatalytic and antimicrobial properties. The Ag-doped TiO2 NPs were made from a simple, costs effective, aqueous green nanosynthesis process, and the end material only contains 0.01–0.05% Ag. As this mortar is intended to both combat atmospheric pollution, and create more durable/lower maintenance building façades (plastering and finishing) by limiting attack from microorganisms and pollutants, its photocatalytic anti-pollution activity under solar and visible (no UV) light for nitrous oxide (NOx) and volatile organic compound (VOC) removal was studied. The addition of dopants did not significantly alter the physical properties or curing of the mortar, while it showed excellent photocatalytic activity under sunlight, The mortars with only 1 and 5wt% additives degraded 10.6% and 21% NOx after 45mins, respectively, comparing well to a value of 50% for a pure TiO2/Ag+ sample. They also degraded VOCs under visible light, of the kind used for lighting inside buildings, with no UV component. As the NPs are contained in the whole of the mortar layer, not just as a coating, if the surface is chipped or damaged this mortar will not loose its photocatalytic capabilities.