Microwave-Assisted Synthesis of Carbon-Based (N, Fe)-Codoped TiO2 for the Photocatalytic Degradation of Formaldehyde

Abstract

A microwave-assisted sol–gel method was used to synthesize (N, Fe)-codoped activated carbon (AC)/TiO2 photocatalyst for enhanced optical absorption in the visible light region. The prepared samples were characterized via X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller analysis, ultraviolet–visible light spectroscopy, X-ray photoelectron spectroscopy, and photoluminescence spectroscopy. The results showed no significant difference in the surface area of AC/TiO2 (approximately 500 m2/g) after doping. TiO2 was uniformly distributed on the surface of AC, which exhibited coexisting anatase and rutile structures with a mean crystallite diameter of approximately 20 nm. N and Fe monodoping on AC/TiO2 reduced the energy band gap of TiO2 to 2.81 and 2.79 eV, respectively, which mainly attributed to the impurity energy formed in the energy gap of TiO2. In (N, Fe)-codoped AC/TiO2, N and Fe are incorporated into the TiO2 framework and narrow the band gap of TiO2 to 2.58 eV, thereby causing a large redshift. Codoping of N and Fe enhanced the production of hydroxyl radicals (⋅OH) and improved the photocatalytic activity of the resultant AC/TiO2 compared with those of undoped and N- or Fe-monodoped AC/TiO2. N-Fe-AC/TiO2 degraded 93 % of the formaldehyde under Xe-lamp irradiation. Moreover, the photocatalyst was easily recyclable. In summary, a novel and efficient method to mineralize low concentrations of HCHO in wastewater was discovered.

Study on photocatalytic performance of cerium-graphene oxide-titanium dioxide composite film for formaldehyde removal

“…It is also observed that the GO‐TiO 2 shows better visible light‐induced degradation rate of formaldehyde than bare TiO 2 , indicating the GO doping could raise the photo quantum efficiency and increase the number of hydroxyl groups to enhance the photocatalytic effect. In comparison with TiO 2 and GO‐TiO 2 , Ce‐GO‐TiO 2 shows the best photocatalytic efficiency and its percentage of formaldehyde removal is 83.8% under simulated sunlight of 7 h, which is a higher effect than that observed for N‐TiO 2 and Ce‐TiO 2 . The HCHO degradation rate of these catalysts described in the literature with different metal or non‐metal doping are only approximately 60% in visible light irradiation.…”

Photocatalytic degradation evaluation of N-Fe codoped aligned TiO2 nanorods based on the effect of annealing temperature

“…The N-Fe codoped TiO 2 nanorods contained not only Ti, O, and C elements, but also N and Fe. The present of nitrogen in the nanorods was corroborated by a single peak (N 1s spectrum) around 400 eV, which can be related to the formation of Nanions incorporated in the TiO 2 as O-Ti-N structure feature [45]. Figure 4(b) illustrates the high resolution XPS spectra of the Fe 2p region taken on surface of the N-Fe codoped TiO 2 nanorods annealed at 400-800 ℃.…”

“…This suggests that some Ti 4+ ions are changed to a lower oxidation state, and thereby TiO 2 lattice is modified due to N and Fe substitution. Lower binding energy can also be explained on the basis of the formation of Fe-O-Ti and N-O-Ti bonds in the framework of TiO 2 [45]. The weight percentages of detected Fe and N dopants within the undoped TiO 2 nanorod and N-Fe codoped TiO 2 nanorods after annealing at various temperatures are listed in Table 1.…”

Green and Rapid Synthesis of Copper-Doped TiO2 Nanoparticles with Increased Photocatalytic Activity

“…By taking in account the principles of Green Chemistry 31 , a benign protocol is obtained for the conventional doped TiO2 photocatalyst synthesis. Microwave synthesis is one of the upcoming method for synthesis of nanoparticles 32 , which is a rapid method that reduces time into few minutes as against conventional synthesis taking hours. Use of plant extract omits the use of chemicals.…”