Aerosol Processing and Photocatalytic Degradation of Ag-TiO₂ Composite Nanoparticles

다국어 초록 (Multilingual Abstract)

This study reports the gas-phase synthesis and characterization of Ag-TiO₂ composite nanoparticles (NPs), and their applications into photo-degradation of organic materials (e.g., methylene blue) under the irradiation of UV and visible light. The effects of surface plasmon resonance (SPR) and electron sink of Ag-TiO₂ composite NPs were made for photo-degradation of organic materials-based solution. Ag-TiO₂ composites NPs with different amounts of Ag(i.e., 0.5, 1. 2 and 5wt%) prepared by spray pyrolysis method using the mixture of TiO₂ and AgNO₃ as precursor solutions. All prepared photocatalysts were characterized using various technics, including crystalline phase, morphology, chemical composition, and optical property measurements. It was clearly observed that the optimized amount of Ag (i.e., 1 wt%) in the TiO₂ matrix confirmed that the optical excitation was successfully driven by visible light irradiation. This noteworthy enhancement was ascribed to the local SPR, which enabled Ag-TiO₂ composite NPs to optically absorb the visible light spectrum. Under the visible light irradiation test conditions for the various MB solutions dispersed with Ag-TiO₂ composite NPs, the rate constant(k) of first-order reaction that characterizes the photocatalytic reactivity values were observed to be ~ 0.232 h^-1 for pure TiO₂ and ~0.396 h^-1 for Ag (1 wt%)-TiO₂, respectively. The Ag (1 wt%)-TiO₂ composite NPs under visible light irradiation showed 70% increase in photocatalytic reactivity compared with pure TiO₂. In addition, the prepared Ag-TiO₂ composite NPs had the excellent photocatalytic activity under UV light irradiation because metallic Ag can act as an electron trap to inhibit electron-hole recombination. Similarly, under the UV light irradiation test conditions for the various MB solutions dispersed with Ag-TiO₂ composite NPs, the k values were observed to be ~0.260 h^-1 for pure TiO₂ and ~0.424 h^-1 for Ag (1 wt%)-TiO₂, respectively. The Ag (1 wt%)-TiO₂ composite NPs under UV light irradiation showed 63% increase in photocatalytic reactivity compared with pure TiO₂