Preparation And Mechanism Of Carbon-modified TiO₂ Photocatalyst

TiO2. as a kind of novel photocatalyst, was widely researched in photocatalysis field due to its excellent chemical stability, resistibility to light corrosion, nontoxic characterization and low cost. However, the band gap of 3.2 eV and the low quantum efficiency during photocatalysis inevitably suppress its response in visible light reagion and the photocatalytic activity. Hence, many researchers have done a lot of work on the modification of TiO2.In Chapter 2 of this thesis, a synthesized water soluble phenol formaldehyde resin (PF) and commercial P25 were calcined together at 350℃for 2 h under N2 atmosphere to obtain carbon modified TiO2. XRD, SEM, XPS and UV-vis DRS were utilized to characterize the as-prepared samples. C-modified TiO2 showed higher activity for the photodegradation of methyl orange (MO) than P25.Next, we used TiSO4 as Ti precursor and the synthesized PF as carbon source to prepare carbon modified TiO2 catalysts (PFTx series) through hydrothermal method. It was found that the PFTx series samples showed much higher visible photocatalytic activity on the degradation of MO than blank TiO2, meanwhile, the subsequent post-treatments to the PFTx series samples have been done such as washing by [HCl/ethanol] liquor, [NaOH/ethanol] liquor and tetrahydrofuran (THF). It was found that the photocatalytic activity of PFTx for the degradation of MO was enhanced after washing process. XPS, TG-TGA, TEM, FTIR and 'H-NMR were utilized to characterize these samples before and after rinsing, we deemed that PF endured cross-linking and carbonization courses on the surface of TiO2, which finally formed graphite-like carbon (GC). oxidation graphite-like carbon (OGC), PF and cross-linked PF. GC and OGC could absorb visible light so as to benefit the photocatalysis.In the last part, P25 was calcined under ethanol atmosphere at 350℃to obtain carbon modified TiO2. XRD, TEM, TG-DTA and DRS were taken to characterize these modified catalysts and the photocatalytic activities were estimated by degradation of 2,4-DCP under visible light. It was found that the sample calcined for 2 hours showed the best photocatalytic activity, while rinsed by NaOH-ethanol solution the activity decreased obviously.