Anatase/brookite biphasic surface fluorinated Fe–TiO2 photocatalysts to enhance photocatalytic removal of VOCs under visible and UV light

Abstract

Volatile organic compounds (VOCs) are categorized as a major group of indoor air pollutants with several adverse health effects on humans. Photocatalytic oxidation (PCO) is a promising in-situ air purification technology for removing indoor VOCs. However, the PCO application by using TiO2 photocatalyst is hindered at high humidity and under visible light irradiation. A facile hydrothermal treatment was used to fabricate biphasic anatase-brookite iron-doped TiO2 with different Fe contents (0.2–4 atomic%) to enhance photoactivity of TiO2 under visible and UV light irradiations. Surface fluorination was then applied to reduce the surface hydrophilicity of Fe–TiO2 photocatalyst with the optimum Fe content (FeTi-0.4%). Surface fluorination of FeTi-0.4% moderates the surface hydrophilicity to repel water molecules from adsorption. The performance of developed photocatalysts was studied toward degradation of gaseous methyl ethyl ketone (MEK) using ultraviolet (UV) and visible light irradiations. The results reveal that iron metal dopants and surface fluorination promoted the performance of synthesized photocatalysts. It was found that the best single-pass removal efficiency was obtained at RH = 20% on F–FeTi-0.4% with values of 54% using visible and 70% using UV illumination. To advance the degradation efficiency and lessen the by-product formation rate, three layers of F–FeTi-0.4% and FeTi-0.4% photocatalyst films were examined. The photocatalytic degradation efficiency for three layers of FeTi-0.4% and F–FeTi-0.4% photocatalyst films were respectively 72% and 80% under UV, and 50% and 60% under visible light illumination. This study provided an effective visible-driven photocatalyst for indoor air purification technology. The results revealed the high MEK removal efficiency under visible light as an environmentally sustainable source of energy, leading to lower indoor pollutions to protect human health.