Shujuan Zhang

Synergistic effects of C-Cr codoping in TiO2 and enhanced sonocatalytic activity under ultrasonic irradiation.

C and Cr co-doped TiO(2) (C-Cr-TiO(2)) sonocatalyst were synthesized by doping TiO(2) with glucose and CrCl(3) in a sol-gel method. The samples were characterized by X-ray diffraction, transmission electron microscopy, ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy, and X-ray photoelectron emission spectroscopy (XPS). C and Cr were detected by XPS analysis. The influence of dopants on the properties and sonocatalytic activity of TiO(2) was studied. The sonodegradation products of methylene blue were analyzed by UV-vis absorption spectroscopy. The presence of C-Cr-TiO(2) catalysts substantially enhanced the sonocatalytic degradation of MB in aqueous suspensions. The possible sonocatalytic mechanisms were also discussed.

Synthesis of porous and trigonal TiO2 nanoflake, its high activity for sonocatalytic degradation of rhodamine B and kinetic analysis.

Porous and trigonal TiO(2) nanoflakes (p-TiO(2)) have been synthesized via a simple hydrothermal calcination process, and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-vis absorption/reflection spectroscopy (UV-vis). The X-ray diffraction patterns of the as-prepared samples show that p-TiO(2) has an anatase structure. Transmission electron microscopy images indicate that p-TiO(2) consists of sheet-like particles with numerous pores about 100nm in diameter. Ultraviolet-visible reflection spectroscopy exhibits that the absorption edge acquires a blue shift with increased calcination temperature. The effects of the calcination temperature, catalyst dosage, and initial rhodamine B (RhB) concentration on the sonocatalytic activity for removing RhB are investigated in detail. The results show that the as-prepared p-TiO(2) obtained at the optimal calcination temperature of 600°C exhibits a higher sonocatalytic activity than commercial P25. Based on the effects of the initial RhB concentration on sonocatalytic activity, the sonocatalytic degradation kinetics of RhB is also investigated.

Co(II)–grafted Ag3PO4 photocatalysts with unexpected photocatalytic ability: Enhanced photogenerated charge separation efficiency, photocatalytic mechanism and activity

Since the photocatalytic capability is determined by the separation and transmission efficiency of photoinduced charges, its improvement remains a challenge for development of efficient photocatalysts. Here, we made large improvement on the surface of Ag3PO4 using Co(II)-grafted Ag3PO4 by a hydrothermal method. During the photocatalytic process, Co(II) was oxidized to Co(III) by the photogenerated holes under visible light radiation, which enhanced the separation efficiency of photogenerated charges. Meanwhile, the Co(III) as-formed could oxidize dye molecules, which recovered the Co(II). The synergy of Co(II) and Ag3PO4 greatly promoted the separation and transmission efficiency of the photogenerated charges, and severely improved the photocatalytic activity of Ag3PO4. The surface grafted Co(II) on Ag3PO4 is responsible for the enhancement of photocatalytic activity.

Sonocatalytic performance of Tb7O12/TiO2 composite under ultrasonic irradiation

A Tb(7)O(12)/TiO(2) composite was successfully synthesized through a hydrolysis-calcination process. The Tb(7)O(12)/TiO(2) composite catalyst was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy, UV-Vis absorption/reflection spectroscopy, and X-ray diffraction (XRD). The heterogeneous sonocatalytic oxidation of amaranth in water, containing dispersed pure TiO(2) and Tb(7)O(12)/TiO(2) composite, was investigated under ultrasonic irradiation. The activity of the Tb(7)O(12)/TiO(2) catalyst is higher than that of pure TiO(2) during the sonodegradation of amaranth. The enhanced sonocatalytic activity of the composite may be attributed to the increase in charge separation efficiency and the presence of surface acidity.

Synthesis and sonocatalytic property of rod-shape Sr(OH)2·8H2O.

A novel rod-shape sonocatalyst Sr(OH)2·8H2O was prepared by a facile precipitation method, and characterized by X-ray powder diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy and UV-vis absorption spectroscopy. Comparative sonocatalytic degradation experiments were carried out in different conditions under ultrasonic irradiation by using rhodamine B (RhB) as the model substrate, indicating that Sr(OH)2·8H2O was highly sonocatalytic. Total organic carbon experiment demonstrated Sr(OH)2·8H2O with mass mineralization of organic carbon. The effects of catalyst amount, initial RhB concentration and ultrasonic energy of degradation were investigated, and the sonocatalyst could be reused 5 times without significant loss of activity. Furthermore, the potent degrading capability was ascribed to ultrasonic cavitation producing flash light/energy which generated radicals (e.g., OH) with high oxidation activity.

Synthesis of AgCl/Ag3PO4 Composite Photocatalysts and Study on Photodegradation Activity Based on a Continuous Reactor

Novel AgCl/Ag3PO4 photocatalysts were synthesized by a simple precipitation method, in which AgCl was coated onto Ag3PO4 particles, as uncovered by X‐ray diffractometry, transmission electron microscopy and ultraviolet–visible spectrometry. Different from previous research on photocatalytic degradation, we studied the performance of methyl orange photodegradation on a small continuous flow reactor. The highest degradation activity of 97% was achieved by the 2 wt.% AgCl/Ag3PO4 after 8 min of visible light irradiation, while pure Ag3PO4 degraded only 71% methyl orange under same conditions. The degradation rate constant of the 2 wt.% AgCl/Ag3PO4 was 1.36 times higher than that of pure Ag3PO4. The AgCl/Ag3PO4 maintained high photocatalytic activity after five cycles, without any significant decrease.

Synthesis of Pb9(PO4)6/Ag3PO4 Composite Photocatalysts with Enhanced Visible Light Photocatalytic Activity

Pb9(PO4)6/Ag3PO4 photocatalysts with different amounts of Pb9(PO4)6 were successfully synthesised by the ion exchange method. The catalysts were characterized by X‐ray diffractometry (XRD), High‐resolution transmission electron microscopy (HRTEM), X‐ray photoelectron spectroscopy (XPS), Brunauer– Emmett–Teller (BET), Fourier transform infrared spectrometry (FT‐IS), and ultraviolet‐visible (UV‐vis) spectroscopy. All Pb9(PO4)6/Ag3PO4 photocatalysts show much higher photocatalytic activities than pure Ag3PO4 under visible light irradiation in the methyl‐orange (MO) decomposition. Especially, the 3.0 wt% Pb9(PO4)6/Ag3PO4 photocatalyst shows the highest photoactivity and also high stability after five cycles. The MO degradation rate during each cycle is almost maintained at 97%. Photo‐electrochemical measurement of photocatalysts verified that the enhancing photocatalytic activity was resulted from the electron‐hole pair high separation. The photocatalytic activity enhancement of Pb9(PO4)6/Ag3PO4 is closely related to ·OH , the main active oxygen species.

A novel WO 3 sonocatalyst for treatment of rhodamine B under ultrasonic irradiation

Pure WO3 powder was prepared from a simple method and applied into sonocatalytic degradation of rhodamine B (RhB), the model compound. The structure and properties of samples were characterized by X-ray diffractometry (XRD), transmission electron microscopy (TEM), ultraviolet–visible (UV–vis) absorption spectroscopy, and photoluminescence (PL) spectroscopy. We studied the effects of WO3 on the sonocatalytic degradation of RhB and the operational parameters such as catalyst dosage and RhB concentration. The experimental results showed that the best sonocatalytic degradation ratio (59.39%) of organic dyes could be obtained when the optimal conditions of 10.00-mg/L initial concentration, 3.00-g/L prepared WO3 powder added amount, 99-W ultrasound output power, and 270-min ultrasonic irradiation were adopted. Under ultrasonic conditions, the degradation rate after addition of WO3 reached the highest activity of 57.9%, and about three times the rate of degradation was not added. Abundant ·OH was induced by WO3 powder under ultrasonic irradiation, which may be the main contributor to the high sonodegradation rate.

Super-high photocatalytic activity, stability and improved photocatalytic mechanism of monodisperse AgBr doped with In.

Monodisperse In(3+) doped AgBr (In-AgBr) nanoparticles were synthesized by a hydrothermal route. The pure AgBr and In-AgBr samples were investigated by X-ray powder diffraction, transmission electron microscopy, ultraviolet-visible absorption spectroscopy, X-ray photoelectron spectroscopy, measurement of total organic carbon, and electron paramagnetic resonance spectrometry. In-AgBr was more photocatalytically active than pure AgBr in photodegradation of 20 mg/L methyl orange under visible light irradiation (λ>420 nm). The 0.05 mol/L In-AgBr sample showed the highest photodegradation efficiency and high stability. The doped In(3+) expanded the light absorption range, reduced the band gap of AgBr and improved the utilization of photons. The additional In(3+) can inhibit the formation of Ag particles on the surface of AgBr, which can further stabilize AgBr. The doped In(3+) in AgBr served as a temporary site for trapping of photoinduced electrons, and thereby obviously restrained the recombination of photoinduced electron-hole pairs on the surface of AgBr. The enhanced photocatalytic ability of In-AgBr may be mainly attributed to the improved separation efficiency of photogenerated charges.