Publicação
TiO2 nanomaterials with photocatalytic self-cleaning properties for smart building façades
| Resumo: | Building façades are continuously exposed to airborne pollutants, leading to surface staining, aesthetic degradation and increased maintenance. To mitigate these effects, a defect- engineering approach is applied to create calcium- and magnesium-incorporated titanium di- oxide (TiO₂) nanomaterials for self-cleaning smart façades. A rapid microwave-assisted sol- vothermal route yields phase-pure anatase nanopowders that are translated into spray-coated films on thermoplastic polyolefin (TPO), a flexible and 100% recyclable polymer substrate rel- evant to façade components. X-ray diffraction (XRD) confirms anatase for all nanopowders and indicates that incorpo- ration does not lead to secondary crystalline phases. Microstructural analysis by scanning elec- tron microscopy (SEM) shows incorporation-driven particle refinement, with particle size de- creasing from 20.1 nm for TiO₂ to 12.5 nm for Ca-TiO₂ and 13.5 nm for Mg-TiO₂. Consistently, the specific surface area increases from 137.8 m²·g⁻¹ for TiO₂ to 237.3 m²·g⁻¹ for Ca-TiO₂ and 235.6 m²·g⁻¹ for Mg-TiO₂. Optical analysis reveals a blue shift of the absorption edge, most pronounced for Ca-TiO₂ nanomaterial. X-ray photoelectron spectroscopy (XPS) confirmed sur- face incorporation of Ca and Mg, and O 1s deconvolution indicates Ca–O-related environments together with an increased contribution of reactive oxygen/hydroxyl species. Density functional theory (DFT) supports a defect-driven mechanism by predicting that calcium promotes oxy- gen-vacancy formation more strongly than magnesium. Under simulated solar irradiation, Ca-TiO₂ exhibited the highest photocatalytic perfor- mance, achieving ~97% Rhodamine B degradation and outperforming TiO₂ and Mg-TiO₂. Ca- TiO₂ also showed the strongest photoinduced hydrophilicity, lowering the water contact angle from ~84° to ~40° after ultraviolet (UV) activation. Overall, earth-abundant calcium incorpora- tion emerges as a practical alternative to durable, high-impact self-cleaning coatings for fa- çade-oriented smart materials. |
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| Autores principais: | Magalhães, Maria Eduarda Carvalho |
| Assunto: | TiO₂ Ca and Mg-incorporation microwave synthesis photocatalysis self-cleaning coatings structural defects |
| Ano: | 2026 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade Nova de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório Institucional da UNL |
| Resumo: | Building façades are continuously exposed to airborne pollutants, leading to surface staining, aesthetic degradation and increased maintenance. To mitigate these effects, a defect- engineering approach is applied to create calcium- and magnesium-incorporated titanium di- oxide (TiO₂) nanomaterials for self-cleaning smart façades. A rapid microwave-assisted sol- vothermal route yields phase-pure anatase nanopowders that are translated into spray-coated films on thermoplastic polyolefin (TPO), a flexible and 100% recyclable polymer substrate rel- evant to façade components. X-ray diffraction (XRD) confirms anatase for all nanopowders and indicates that incorpo- ration does not lead to secondary crystalline phases. Microstructural analysis by scanning elec- tron microscopy (SEM) shows incorporation-driven particle refinement, with particle size de- creasing from 20.1 nm for TiO₂ to 12.5 nm for Ca-TiO₂ and 13.5 nm for Mg-TiO₂. Consistently, the specific surface area increases from 137.8 m²·g⁻¹ for TiO₂ to 237.3 m²·g⁻¹ for Ca-TiO₂ and 235.6 m²·g⁻¹ for Mg-TiO₂. Optical analysis reveals a blue shift of the absorption edge, most pronounced for Ca-TiO₂ nanomaterial. X-ray photoelectron spectroscopy (XPS) confirmed sur- face incorporation of Ca and Mg, and O 1s deconvolution indicates Ca–O-related environments together with an increased contribution of reactive oxygen/hydroxyl species. Density functional theory (DFT) supports a defect-driven mechanism by predicting that calcium promotes oxy- gen-vacancy formation more strongly than magnesium. Under simulated solar irradiation, Ca-TiO₂ exhibited the highest photocatalytic perfor- mance, achieving ~97% Rhodamine B degradation and outperforming TiO₂ and Mg-TiO₂. Ca- TiO₂ also showed the strongest photoinduced hydrophilicity, lowering the water contact angle from ~84° to ~40° after ultraviolet (UV) activation. Overall, earth-abundant calcium incorpora- tion emerges as a practical alternative to durable, high-impact self-cleaning coatings for fa- çade-oriented smart materials. |
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