The present research reports on a successful strategy of titanium dioxide modification with carbon and zirconium, for enhanced photocatalytic activity under UV–vis irradiation. Carbon and/or zirconium modified TiO2 nanoparticles were synthesized via sol–gel hydrothermal method. It was found that both elements positively influence important parameters for the photocatalytic activity improvement, such as crystallite size, diameter of agglomerates and surface area, summing their effects in case of co-doped sample. Moreover, carbon modification shifts the absorption edge toward larger wavelength and decreases band gap energy in opposite to zirconium, which induces blue shift and increases the band gap energy. Thus, modification with two elements at a time narrows the band gap energy of co-doped sample maintaining its high oxidation potential, which along with increased absorption of visible light leads to enhancement in visible and ultraviolet light driven photocatalytic decomposition of methylene blue. It was found that Zr,Csingle bondTiO2 sample is more efficient photocatalyst for both visible and ultraviolet light driven processes than either of the pure or single element modified TiO2.
COBISS.SI-ID: 6071322
The rate of methylene blue and terephthalic acid degradation assisted with double metal-modified catalyst (0.1 mol% Cu and 1.0 mol% Zr) was enhanced as compared with single metal-modified catalysts (0.1, 0.5 mol% Cu and 1.0 mol% Zr). The wet impregnation method was used for copper and zirconium modification of the surface of Aeroxide P25 TiO2 particles. Simultaneous loading of both metals on the surface of P25 leads to an increased specific surface area of the obtained material despite negative Cu influence. The tendency of stabilization and agglomerate size rising with the time for Cu and Zr-modified catalysts were traced by dynamic light scattering (DLS) measurements. The observed optical characteristics suggest that Cu compensated the broadening of band gap caused by Zr loading. Crystal structure of obtained photocatalysts was explored by XRD; morphological data and particle size were obtained by SEM. EDX was used for Zr and Cu content determination. Cu K-edge extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) analytical techniques were used to investigate the local Cu neighbourhood in the samples and to identify copper coordination and valence state of copper species in the synthesized nanocomposites.
COBISS.SI-ID: 6066202
The development of efficient TiO2-based photocatalysts for water treatment is mainly performed by doping with transition metals or by establishing junctions between different phases, metal–semiconductor or semiconductor–semiconductor. We present, for the first time, the synthesis of Zr- and Mn-modified TiO2 by a redesigned sol–gel technique that allows the formation of heterometallic bridges on the TiO2 surface. Cations of the doping metals are located in the pores of mesoporous anatase and attached to the crystalline TiO2 walls. The presence of the Zr enhances the photoactivity of the TiO2 catalyst. However, the introduction of Mn decreases the photocatalytic efficiency in a nonadditive manner. The inhibition effect was assigned to the side reaction between hydroxyl radicals and Mn ions. The fact that Mn effectively scavenges the hydroxyl radicals and, consequently, inhibits the whole oxidation process is direct proof that hydroxyl radicals are the main reactive species in the photocatalytic oxidative processes on TiO2 surfaces in aqueous media and the process of .OH generation is the rate-determining step, which was confirmed using a method based on the decolorization of a commercial dye Bezaktiv Blau in a reaction with Fenton's reagent as a source of hydroxyl radicals.
COBISS.SI-ID: 5943322