실내 공기오염물 분해를 위한 내구성 향상 광촉매의 개발

Abstract

Photocatalysis is a promising technology for indoor air purification because it decomposes volatile organic compounds (VOCs) to harmless CO2 and H2O and maintains removal efficiency even at low concentrations of VOCs such as indoor environment. However, photocatalyst deactivation reduces commercial value for long-term use as an air purification technology. Although various photocatalysts have been fabricated, they have not become an intrinsic solution for reducing photocatalyst deactivation which is commonly observed during the photocatalytic degradation of VOCs. To deal with this problem, this study demonstrated the mechanism of photocatalyst deactivation during VOC degradation and the development of titania-based deactivation-resistant photocatalyst. The physicochemical properties of TiO2 including morphology, surface functional groups, and exposed facets were optimized to develop deactivation-resistant photocatalyst. The VOC-induced photocatalyst deactivation is caused by strong complexation of carbonaceous intermediates that are in-situ generated on the photocatalyst surface. First of all, considering insufficient supply of O2, it was proposed to design porous structures (e.g., TiO2 nanotubes (TNT), freestanding doubly open-ended TiO2 nanotubes (DNT)) as a solution for preventing photocatalyst deactivation. In next part of the study, surface modified TiO2 with fluoride anion and metal cocalyst was developed as a deactivation-resistant photocatalyst because photocatalyst deactivation highly depends on TiO2 surface characteristics. The dual-component surface modification enhanced the formation of mobile OH radicals instead of surface-bound OH radicals. The photocatalytic degradation of VOCs mediated by mobile OH radicals efficiently hindered the deposition of carbonaceous intermediates on the surface of photocatalyst and increased the mineralization efficiency of VOCs. Finally, the dominant {001} facet exposed single-crystalline TiO2 nanotubes (001 facet TNT) was fabricated. Due to its high surface energy, {001} facet is desirable for degradation reaction but difficult to be fabricated. In cooperation with Samsung Electronics, the 001 facet TNT filter (273 x 308 mm2) equipped air cleaner (AX 7000, Samsung) was designed and tested its removal efficiency in indoor environment. The 001 facet TNT filter equipped air cleaner showed 72.1% of total harmful gas removal efficiency under air cleaner standards (SPS-KACA002-132, South Korea) and would be certified as a first air cleaner which get CA mark with solely photocatalyst filter