Abstract
Yb-doped TiO2 (Yb/TiO2) compositions were synthesized by sol-gel method, and the prepared materials were characterized by X-ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse-reflectance spectrum (UV-Vis DRS), transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM), energy dispersive spectrometer (EDS), and N2 adsorption. A beneficiation reagent of benzohydroxamic acid (BHA) was used to test the photocatalytic activity of Yb/TiO2. The characterizations indicate that the doping of Yb could inhibit the crystal growth of TiO2, enhance the specific surface area, increase the binding energy of Ti2p, and also slightly expand the adsorption ranges to visible light. Furthermore, the computation of band structure also indicates that Yb-doped TiO2 could make the forbidden band narrower than pure anatase TiO2, which presents a red shift in the absorption spectrum. As a result of the photodegradation experiment on BHA, Yb/TiO2 (0.50% in mass) sintered at 450 °C displayed the highest catalytic activity for BHA when compared with pure TiO2 or other doped Yb/TiO2 compositions, and more than 89.2% of the total organic carbon was removed after 120 min. Almost all anions, including Cl−, HCO3−, NO3−, and SO42−, inhibited the degradation of BHA by Yb/TiO2, and their inhibition effects followed the order of HCO3− > NO3− > SO42− > Cl−. Cations of Na+, K+, Ca2+, and Mg2+ displayed a slight suppressing effect due to the impact of Cl− coexisting in the solution. In addition, Yb/TiO2 maintained a high photocatalytic ability with respect to BHA after four runs. It is hypothesized that ·OH is one of the main species involved in the photodegradation of BHA, and the mutual transformation of Yb3+ and Yb2+ could promote the separation of electron-hole pairs.
Highlights
TiO2 is considered to be one of the most promising and widely used semiconductor photocatalyst materials, primarily due to its chemical stability, unique optical properties, nontoxicity, strong oxidizing power, and low cost [1]
benzohydroxamic acid (BHA) was used to test the photocatalytic activity of the Yb-doped TiO2 (Yb/TiO2) composition
The diffraction peak of pure TiO2 is relatively narrow compared with Yb/TiO2
Summary
TiO2 is considered to be one of the most promising and widely used semiconductor photocatalyst materials, primarily due to its chemical stability, unique optical properties, nontoxicity, strong oxidizing power, and low cost [1]. Doping with metal ions in the TiO2 lattice has been proven to be an efficient way to enhance photocatalytic activity [3,4]. Research has shown that the doping of rare earth ions can effectively improve the photocatalytic activity of TiO2 [5,6,7]. Res. Public Health 2017, 14, 1471 have the electronic structure of 4f, which exists at the ground and excited states. The doping of rare earth could reduce the recombination of photogenerated electron-hole pairs [8,9]. Our previous study indicated that La/TiO2 possessed high activity with respect to BHA [13]. BHA was used to test the photocatalytic activity of the Yb/TiO2 composition. The effects of Yb-doping amount, calcination temperature, common anions and cations in the photodegradation of BHA, and the degradation mechanism of BHA were investigated, and the reuse of doped catalyst was investigated
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