TiO₂-SiO₂ Coatings with a Low Content of AuNPs for Producing Self-Cleaning Building Materials.

Manuel Luna,María Mosquera,M Gil,Juan Delgado

doi:10.3390/nano8030177

Abstract

The high pollution levels in our cities are producing a significant increase of dust on buildings. An application of photoactive coatings on building materials can produce buildings with self-cleaning surfaces. In this study, we have developed a simple sol-gel route for producing Au-TiO2/SiO2 photocatalysts with application on buildings. The gold nanoparticles (AuNPs) improved the TiO2 photoactivity under solar radiation because they promoted absorption in the visible range. We varied the content of AuNPs in the sols under study, in order to investigate their effect on self-cleaning properties. The sols obtained were sprayed on a common building stone, producing coatings which adhere firmly to the stone and preserve their aesthetic qualities. We studied the decolourization efficiency of the photocatalysts under study against methylene blue and against soot (a real staining agent for buildings). Finally, we established that the coating with an intermediate Au content presented the best self-cleaning performance, due to the role played by its structure and texture on its photoactivity.

Highlights

Today, the concentration of pollutants is significantly high in big cities and industrial environments
Photoactive surfaces have been produced on a great variety of building materials, such as glass [5], ceramics [6], roof tiles [7] and especially in stones [8,9,10,11,12,13,14], by applying, mainly, TiO2 nanoparticles (TiO2NPs) dispersed in a solvent (water or volatile organic compunds (VOCs)), as a coating
We evaluated the complete oxidation of methylene blue (MB) using a HiCube mass spectrometer from Pfeiffer (Asslar, Germany), employing a 10 mL/min of O2 (4%)/Ar flow, over a cylindrical (ø5 × 2 cm) stone piece treated with photocatalytic coating and stained with MB

Summary

Introduction

The concentration of pollutants is significantly high in big cities and industrial environments. Small particles and greasy deposits are adhered to building surfaces by organic binders such as hydrocarbons and fatty acids [1]. These pollutants promote a significant change in the aesthetic of historic and modern buildings of our cities and, it is responsible for costs investments in building conservation. Photoactive surfaces have been produced on a great variety of building materials, such as glass [5], ceramics [6], roof tiles [7] and especially in stones [8,9,10,11,12,13,14], by applying, mainly, TiO2 nanoparticles (TiO2NPs) dispersed in a solvent (water or volatile organic compunds (VOCs)), as a coating. Cracks resulting from the accumulation of TiO2NPs are commonly produced [11,18,19]

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Methods

Conclusion