Pros and Cons of Photocatalytic Building Materials Applied to Air Remediation

SALVADORES, FEDERICO; ZACARÍAS, SILVIA M.; ALFANO, ORLANDO MARIO; BALLARI, MARÍA DE LOS MILAGROS

Rostock

Conferencia; The 25th International Conference on Semiconductor Photocatalysis and Solar Energy Conversion (SPASEC-25); 2022

Photocatalytic building materials emerge as an alternative technology to improve air quality and prevent environmental and health problems. The photocatalytic oxidation process involves a semiconductor, generally TiO2, which in the presence of oxygen and radiation of energy equal to or greater than the bandgap, generates electron-hole pairs capable of oxidizing a wide range of pollutants or removing pathogenic microorganisms from air streams. Some case studies are related to photocatalytic building materials, both at laboratory and real scales, applied to the chemical and biological remediation of indoor and outdoor air. Many types of construction materials have been analysed, such as concrete, cement, coatings, papers and paints, among others, formulated with different doped or commercially available TiO2 under UV and/or visible radiation. In this work, the advantages and limitations of this technology for the control of atmospheric pollution are presented and the main operating variables that affect the air decontamination process are discussed. One of the main advantages of this sustainable technology to control atmospheric pollution is based on the use of solar radiation as an energy source for outdoor air remediation or artificial lighting for indoor environments. In addition, the decontamination process through these special building materials can be carried out on-site with the sole existence of oxygen as an extra reagent and the irradiation with natural or artificial ultraviolet/visible light.The main large-scale demonstrations with photocatalytic building materials were mainly conducted in outdoor environments with UV solar radiation. In contrast, the application of these building materials in illuminated indoor environments with visible radiation or scarce UV radiation has been less investigated. Although TiO2-based photocatalysts have shown great potential as a low-cost and environmentally friendly material for air purification, another major limitation that has hindered their application to indoor studies is the availability of photocatalysts with extended activity in the visible spectrum.Other critical issues that need to be highlighted for further in-depth study are the identification of the various agents that could affect the oxidation process and the original properties of photocatalytic building materials. Among them, it was possible to identify the generation and accumulation of intermediates of the main reaction and the variation of the environmental conditions of the atmosphere, such as irradiation level, relative humidity, and temperature, agents that can negatively affect the durability and stability of the photocatalytic material as well as the rate of the process.