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Photocatalytic water spitting is one way of hydrogen production from energy conservation and emission reduction. However, the activities of most photocatalytic materials need to be enhanced by cocatalysts. In this study, we explored to control the photocatalytic hydrogen evolution (PHE) ability of cadmium sulfide (CdS) without any cocatalysts by temperature and largely improve its photocatalytic ability. It was experimentally found the activity of CdS without cocatalysts under heating conditions (100 °C) was much higher than that at room temperature, and increased first and then decreased, with a maximum at 50 °C (169716 umol/h, 68.2 % , λ = 450 nm). Therefore, it is convenient to control the hydrogen production activity of CdS by temperature. The large increment of photocatalytic activity was realized because the temperature complemented the shortcomings of semiconductors in light absorption, and together with light radiation, increased the electron migration rate and density, quantity of surface adsorbed H

In this study, with silicon carbide as a pyroelectric catalyst, the reactor was alternatively removed between a hot water bath and a cold water bath, which ensured the cold-hot circulation within 300–333 K at room temperature. Then the pyroelectric performance of silicon carbide was utilized in hydrogen evolution from water splitting. With methanol as the sacrificial agent, the hydrogen yield after 20 cycles was up to 32.84 μmol/g. Silicon carbide demonstrates high catalytic activity and together with its chemical stability, it shows potential in hydrogen production from water splitting under cold-hot alternation.

In this paper, a 3D Bi2WO6 microflower was synthesized by precipitation method. The material belongs to the mm2 point group and is a piezoelectric material with an asymmetric structure. The material structure and morphology of the catalyst were characterized in detail by XRD, SEM, UV–vis and XPS, and the performance of the material to degrade Rhodamine B aqueous solution under different conditions was studied. The results showed that the material has excellent the performance of piezoelectric catalytic degradation. Bi2WO6 microflower's multiple petal surfaces provide multiple positive and negative plates to enhance its piezoelectric effect. The polarized charge generated by mechanical vibration on the surface of Bi2WO6 microflower forms a large number of hydroxyl and superoxide radicals in the aqueous solution, which are the main active species that reflect their degradation activity.

With the continuous growth of global energy demand, the artificial photosynthetic system of photocatalytic decomposition of hydrogen production has been widely concerned, CdZnS, a photocatalyst based on solid solution, has shown good performance. In order to avoid the rapid recombination of photogenerated electron and hole, metal boride is added as a catalyst to enhance its photocatalytic hydrogen production performance. We prepared CdZnS photocatalyst by hydrothermal method, and synthesized different proportions of NiB/CdZnS catalyst by programmed heating method and calcined it at 773K. Characterized by XRD, XPS, uv–vis diffuse reflection and other methods, CZS solid solution and NiB/CdZnS were synthesized, and the absorption edge of NiB/CZS was redshifted relative to the pure CdZnS. The addition of NiB can effectively inhibit the recombination of electrons and holes to improve the separation efficiency of photogenerated charge, and its content has an impact on photocatalytic activity. We found that under visible light irradiation, when the content is 15 wt%, the hydrogen production was the highest. The optimal quantum efficiency was 13.3%, and the hydrogen production reacheed 8137 μmol/g/h, which is 17 times that of pure CdZnS. The addition of NiB greatly improved the photocatalytic performance of CdZnS.

Carbon quantum dots/bimetal phosphide (CQDs@NiCoP) catalysts for electrocatalytic hydrogen evolution reaction were synthesized via a facile annealing method. In a 0.5 M H2SO4 system, the 30 mg/L CQDs@NiCoP catalyst performed well with high electrocatalytic activity, lower initial overpotential than pure NiCoP (108 vs. 182 mV) and lower Tafel slope of 80 mV/decade. The enhancement of hydrogen evolution reaction activity was probably because the addition of CQDs enhanced the catalyst conductivity and significantly accelerated charge transfer.

Novel carbon black (CB)/Ag3PO4 compound photocatalysts were synthesized from a hydrothermal method and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and electrochemical methods. The photocatalytic oxidation ability of CB/Ag3PO4 was evaluated through methyl orange degradation experiments under visible light irradiation. The CB/Ag3PO4 showed higher photocatalytic activity than pure Ag3PO4. It was indicated the compound catalysts could absorb and utilize more optical energy to improve the photocatalytic activity, which was attributed to the ability of carbon black to accelerate the electron-hole separation. In particular, the methyl orange photocatalytic degradation rate over the 7 mg/L CB/Ag3PO4 was 1.6 times that of Ag3PO4. And the results of the cyclic experiment show that the photocatalyst has good stability. Moreover, the mechanism about the photocatalytic activity of CB/Ag3PO4 compounds was investigated. In this photocatalytic reaction, •OH was the major active substrate responsible for the visible-light-driven degradation.

The technology of photocatalytic hydrogen evolution (PHE) by water splitting is a clean and sustainable approach to solve energy crisis and environmental problem. Many efforts have been made to develop new materials for this technology. In the photocatalytic water splitting, the cocatalyst is pivotal in improving the photocatalytic ability of the main catalyst by transferring electrons and providing active sites of H+ reduction. Here we report a new bimetal phosophide cocatalyst of NiCoP. The NiCoP can significantly improve the ability and durability of PHE for water splitting. The PHE rate is maximized to 28412.6 μmol/g/h over a 8 wt.% NiCoP/CdS photocatalyst, which is 361 times of the 1 wt.‰ Pt/CdS (78.7 μmol/g/h) under the same water splitting condition. The apparent quantum yield in 100 h is about 36.8%. The long-time photolysis water reaction for 100 h with increasing photocatalytic activity exhibits that the NiCoP in CdS is highly stable in water spitting. We can control and improve the photocatalytic activity by regulating the Ni–Co ratio, which is an advantage relative to single-metal phosphides. The photo-induced charge transfer over NiCoP has been proved by photoluminescence and methyl viologen dication. It is indicated the non-noble-metal cocatalyst NiCoP can substitute noble metal to significantly enhance the PHE activity of photocatalysts.

Pb9(PO4)6/Ag3PO4 photocatalysts with different amounts of Pb9(PO4)6 were successfully synthesized 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. This article is protected by copyright. All rights reserved.

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.

Bulk and SiO 2 supported iron phosphide (FeP) samples were synthesized with a mixture of iron sulfide (FeS) and sodium hypophosphite (NaH 2 PO 2 ·H 2 O). The physical and chemical properties of the as-prepared FeP/SiO 2 were studied by X-ray powder diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and thermal gravimetric analysis. Dibenzothiophene was effectively hydrodesulfurized over the as-synthesized FeP/SiO 2 (Fe: 10 wt.%). The as-prepared FeP/SiO 2 shows a higher activity than the FeP/SiO 2 obtained by the temperature-programmed reduction route. The Fe–P–S species constructed in situ may be responsible for the higher activity. The method is also feasibly applicable in synthesizing other transition metal phosphides.

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.

Silica-supported NiCoP (NiCoP/SiO2) catalysts were prepared by reducing nickel chloride (NiCl2·6H2O) and cobalt chloride (CoCl2·6H2O) with red phosphor (P) precursors. Physicochemical properties were determined by inductively coupled plasma spectroscopy, N2 adsorption experiment, X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, and differential scanning calorimetry. Catalytic activities against the hydrodesulfurization of dibenzothiophene were evaluated in a fixed-bed reactor in flowing H2. The as-prepared NiCoP/SiO2 catalyst exhibited high hydrodesulfurization activities and selectivity for indirect hydrodesulfurization (>90%).

The controlled synthesis of catalyst Ni 2 P/SiO 2 was achieved using NiS as a precursor. NiS was reduced by NaH 2 PO 2 ·H 2 O at 350 °C for 1 h to produce Ni 2 P/SiO 2 . The catalyst was characterized using X-ray powder diffraction, transmission electron microscopy (TEM), inductively coupled plasma atomic emission spectroscopy, N 2 adsorption specific surface area measurement, and thermal gravimetric analysis. The TEM showed that the Ni 2 P particles in size of about 20–30 nm were highly dispersed on the carrier SiO 2 . The as-prepared Ni 2 P/SiO 2 contained a small amount of sulphides. The hydrodesulfurization activity of Ni 2 P/SiO 2 (10 wt.% Ni) was studied for dibenzothiophene at 320 °C. The as-obtained Ni 2 P/SiO 2 using NiS as a precursor was more active than Ni 2 P/SiO 2 synthesized with NiO as a precursor via the same route. We suppose that additional sulphide is responsible for the improved activity.

A novel sonocatalyst CdS was prepared by a facile precipitation method, and characterized by X-ray powder diffraction, transmission electron microscopy, UV-vis absorption spectroscopy, and photoluminescence spectroscopy. Comparative sonocatalytic degradation experiments were carried out in different conditions under ultrasonic irradiation and with rhodamine B (RhB) used as the model substrate. Results indicate that CdS is a highly active sonocatalyst. The efficiency of RhB sonodegradation in aqueous solutions within 4 h is up to 70% after the addition of CdS. Abundant •OH during the RhB sonodegradation was detected, which may be responsible for the high sonodegradation rate over CdS under ultrasonic radiation.

Pure WO

Supported bimetal phosphide (NiCoP/SiO 2 ) catalysts with variable Ni/Co mole ratios at low temperature were synthesized by a novel route using sodium hypophosphite (NaH 2 PO 2 ·H 2 O), nickel acetate (Ni(AC) 2 ·4H 2 O) and cobalt acetate (Co(AC) 2 ·4H 2 O) as materials. The structure, composition and properties of the as-prepared catalysts were characterized by X-ray diffraction, inductively coupled plasma atomic emission spectroscopy, high resolution transmission electron microscope, Fourier transform infrared spectroscopy, N 2 adsorption measurement, thermogravimetric analyzer and gas chromatograph-mass spectrometer. The transmission electron microscope analysis showed the as-obtained NiCoP nanoparticles were highly dispersed on the SiO 2 support. The hydrodesulfurization conversion reached 73.7% over the as-synthesized NiCoP/SiO 2 (Ni: 10 wt.%, Co: 10 wt.%), which resulted from the highly disperse NiCoP active phase on the SiO 2 support. In addition, the preparation mechanism and desulfurization path were also discussed in detail.

Bi-doped Ag 3 PO 4 was synthesized by an ion exchange method, and its structure and properties were characterized systematically. Doping Bi 3+ ions into the crystal lattice of Ag 3 PO 4 changed the properties of particles, reduced the valence band position and widened the band gap of Ag 3 PO 4 . The doped Bi 3+ ions have replaced P 5+ ions of P–O tetrahedrons according to the XRD and XPS analysis. The testing of methyl orange (MO) photodegradation showed that 2 wt% Bi-doped Ag 3 PO 4 had the highest activity, with the degradation rate reaching 90.7% after 6 min (1 g/L catalyst) when pure Ag 3 PO 4 degraded only 27.3% of MO. Its degradation rate constant was 4.5 times that of undoped Ag 3 PO 4 . Particularly, 2 wt% Bi-doped Ag 3 PO 4 managed to photodegrade high-concentration (40 mg/L) MO (1 g/L catalyst), with the degradation rate constant 7.3 times that of undoped Ag 3 PO 4 . •OH radicals were the main active species in the oxidation of MO over Bi-doped Ag 3 PO 4 . Doping Bi 3+ substantially reduced OH defects on the surface of Ag 3 PO 4 , which significantly increased the degradation efficiency of MO over Ag 3 PO 4 . In addition, the density-functional theory calculation revealed that the influence of Bi dopants on the electronic structure may be an important reason for the enhanced photocatalytic performance of Ag 3 PO 4 .

A NiCoP/SiO 2 catalyst was fabricated by solid phase reaction of nickel chloride (NiCl 2 ) and cobalt chloride (CoCl 2 ) with potassium dihydrogen phosphate (KH 2 PO 3 ). The structure and properties of NiCoP/SiO 2 were characterized by X-ray powder diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, thermal gravimetric analysis and Brunauer–Emmett–Teller in detail. A mechanism was postulated based on the results of thermal gravimetric analysis. The as-prepared NiCoP/SiO 2 catalyst had excellent hydrodesulfurization activity, as indicated by using dibenzothiophene as the reactant. Hydrodesulfurization occurred sequentially following hydrogenation of dibenzothiophene and desulfurization in the presence of NiCoP/SiO 2 .

A simple and efficient approach to the preparation of hollow or porous metal phosphide nanoparticles was presented. Bulk and supported Ni2P, CoP, FeP, and Cu3P were successfully synthesized by reducing metal pyrophosphate precursors in flowing hydrogen. The structural properties of these samples are investigated using X-ray powder diffraction, transmission electron microscopy, inductively coupled plasma and X-ray photoemission spectroscopy. The Ni2P/SiO2 catalysts were used for the gas phase catalytic hydrodesulfurization of dibenzothiophene. The hydrodesulfurization activity of the catalyst reached 99% when the reaction temperature was 340 °C. In the paper, a possible reaction mechanism was discussed to form Ni2P, CoP, FeP, and Cu3P. The route and mechanism could also be applied to the preparation of other metal phosphides.

AgBr sonocatalysts were prepared by a simple method. The AgBr sonocatalysts exhibited excellent sonocatalytic activities against the decolorization of methylene blue, rhodamine B, and methyl orange. By determining the content of OH radicals in the ultrasonic degradation of organic dyes, many OH radicals were detected, which may be responsible for the high sonodegradation rate over AgBr under ultrasonic radiation. Based on the effects of the initial dye concentration on the sonodegradation, we also discussed and analyzed the kinetic data, and the results are consistent with the first-order kinetic rate equation.

A new catalyst of silver tyipolyphosphate (Ag5P3O10) for sonodegradation of dyes, was prepared by a hydrothermal route. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis absorption spectroscopy (UV–vis), photoluminescence spectra (PL) and N2 adsorption–desorption methods. The degradation of dyes in water was investigated under ultrasonic irradiation in the presence of Ag5P3O10. The result shows Ag5P3O10 has the excellent sonodegradation activity of dyes. A large number of hydroxyl ( OH) radicals formed under ultrasonic radiation, and the content of OH radicals increased with increased radiation time. This phenomenon provided the main basis for the high sonodegradation activity of Ag5P3O10 under ultrasonic radiation. The kinetic model and its parameters were also discussed in detail.

Magnesium phosphide (Mg3P2) microstructures having microwire shapes with ultrahigh-aspect-ratio and three-dimensional (3D) urchin, flower, and branched shapes (myriapod or leaf) are synthesized using a one-step reaction without any catalysts or templates. The microstructures with different shapes are easily controlled through various temperatures. With increasing reaction temperature, the morphology of Mg3P2 microstructures changes from microwires with ultrahigh-aspect-ratio to branched shapes similar to myriapods or leaves. The growth mechanisms of these microstructures are discussed in detail.

The reaction of alcohols and carboxylic acids catalyzed by acids is the traditional method used to prepare esters in the chemical industry. In this study, we report the synthesis of active graphitic carbon nitride (g-C3N4) that may be used in the one-step reaction between benzaldehyde and alcohol to promote the selective formation of esters under visible light irradiation. Compared with the reaction carried out without illumination, g-C3N4 showed obvious improvements in ester formation. The presence of tin dioxide can also contribute to the formation of esters under visible light irradiation. The use of g-C3N4 for the esterification of various alcohols was explored, and the catalyst showed promising results.

A series of porous BiOI nanoparticles were successfully synthesized via a hydrothermal process. The BiOI nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV–vis absorption/reflection spectroscopy (UV–vis). The results showed that the as-prepared BiOI sonocatalyst generally had flake-like-shaped, porous particles about 100 nm in diameter. The sonocatalytic activity of BiOI was evaluated by the degradation of methylene blue (MB) in aqueous solution under ultrasonic irradiation. The effects of the catalyst dosage and initial MB concentration on the sonocatalytic degradation efficiency of MB were studied. The sonocatalytic degradation kinetics of MB was also investigated. The results showed that the degradation kinetics of MB fitted pseudofirst-order kinetics and the Langmuir–Hinshelwood model.

A new method for the preparation of bimetal phosphides was reported. Bulk and SiO2-supported porous NiCoP were obtained from the direct thermal treatment of precursors containing nickel, cobalt salts, and sodium hypophosphite mixed mechanically under flowing nitrogen. Compared with traditional H2-temperature-programmed reduction method, the method developed provided a simple one-step way to produce bimetal phosphides with a relatively low temperature. In the report, a possible preparation mechanism was discussed to form NiCoP. The route and mechanism could also be applied to the preparation of other bimetal phosphides. In comparison with the Ni2P/SiO2 catalyst, the NiCoP/SiO2 showed a higher hydrodesulfurization activity for dibenzothiophene.

Bulk and supported Ni 2 P catalysts were prepared through a novel method using a solid mechanical mixture of Na(H 2 PO 3 ) 2 and NiCl 2 ·6H 2 O in definite molar ratio as a precursor. The precursor was heated at 200–300 °C for 1 h in flowing N 2 to form Ni 2 P catalysts. X-ray diffraction and X-ray photoelectron spectroscopy were used to study the formation of the phase. The mechanistic progress of Ni 2 P was studied using thermo gravimetry and the results indicate that NiCl 2 is reduced by PH 3 produced from decomposition of NaH 2 PO 3 at 250 °C. The dibenzothiophene (DBT) hydrodesulfurization (HDS) activity of the Ni 2 P/SiO 2 catalysts was measured, and good activities were observed at different temperatures.

A visible-light S-doped BiSe photocatalyst was prepared by the solvothermal method in ethanediamine solvent. The photocatalyst was characterized by X-ray diffraction, UV–vis diffusive reflectance spectroscopy, and X-ray photoemission spectroscopy. Its activity was evaluated by photocatalytic oxidation of methylene blue under visible-light irradiation (λ > 400 nm). The reaction time and temperatures, as well as the precursor composition of S-doped BiSe, were found to exert great influence on photocatalytic activity.

One-step solvothermal synthesis is proposed for the preparation of nanocrystalline InOOH doped with Se2+ ions. The structural properties of these products are investigated using X-ray powder diffraction (XRD), electron microscopy, UV–vis diffusive reflectance spectroscopy, and X-ray photoemission spectroscopy (XPS). Doping of Se2+ ions makes the absorption edge of the InOOH shift into the visible region. Effective photodegradation of the methylene blue aqueous solution is achieved under visible light irradiation (λ > 400 nm), revealing its potential applicability in air and water purifications.

Composite photocatalysts composed of NiO and CaO have been prepared via mechanically mixing of the two powders. The as-synthesized NiO–CaO products were characterized by X-ray diffraction (XRD) and UV–vis spectrometry. The experimental results showed that the absorption wavelength range of the mixed NiO–CaO sample was notably extended towards the visible-light region (400–450 nm). Photocatalytic activity of the NiO–CaO composite was evaluated based on the decomposition of methylene blue under visible-light irradiation. The effects of CaO doping and the duration of heat treatment on the durability of the NiO–CaO products have been investigated in detail. Factors influencing photocatalytic activity and the mechanism of photocatalysis were also addressed.

A series of ternary Zn0.2Cd0.8S photocatalysts were synthesized by a solvothermal method and characterized by X-ray powder diffraction (XRD) and Ultraviolet–visible spectroscopy (UV–vis). The photocatalytic reaction was carried out in a quartz reactor irradiated under a 300-W Xe lamp. The experimental results showed that the Zn0.2Cd0.8S photocatalysts exhibited a high photocatalytic activity for the photodegradation of methylene blue. The effects of the thermal treatment of photocatalysts, the concentration of methylene blue aqueous solutions, and of the different sulfides in the preparation process on photocatalytic performance were also discussed.

S–N-codoped TiO2 powders have been synthesized through a facile one-step sol–gel method by using tetrabutyltitanate and thiourea as precursors. The S–N-codoped TiO2 treated at 500 °C showed the highest photocatalytic activity for degrading methylene blue under visible light irradiation. XRD, XPS and UV–vis studies revealed that the high visible-light photocatalytic activity of the doped TiO2 may originate from the synergetic effect of sulfur and nitrogen codoping into TiO2.

C–N-codoped titanium dioxide photocatalysts were prepared by a hydrolysis–polymerization–calcination method. Analysis of X-ray photoemission spectroscopy indicated carbon and nitrogen were effectively doped into TiO2 particles. Furthermore, it became apparent that most of the nitrogen dopants were likely present in the chemical environment of oxidized nitrogen, where the majority of carbon atoms formed a mixed layer of deposited active carbon and C–O bond species on the surface of the TiO2 particles. The results of the photodecomposition of methylene blue under visible-light irradiation suggest the photocatalytic activity of the C–N-codoped TiO2 was greatly improved when compared with that of the undoped TiO2 photocatalyst.

A novel visible-light-sensitive strontium carbonate photocatalyst with high photocatalytic activity was prepared from strontium hydroxide by calcination in air at moderate temperature. The SrCO3 photocatalyst was characterized by UV–vis diffuse reflection spectrum, X-ray powder diffraction and Brunauer–Emmett–Teller. The photocatalytic activity of the photocatalyst was evaluated by photocatalytic oxidation of methyl blue (MB) under visible-light irradiation (λ > 400 nm). The results show that the photodegradation efficiency of MB on the SrCO3 catalyst reached 98.2% after irradiation for 180 min, which is much higher than that of commercial TiO2 (P25). Effects of heat treatment on the photocatalytic activity of the photocatalyst SrCO3 were also investigated.

Supported nickel phosphides were prepared by treating an amorphous Ni–B alloy on silica–alumina support with phosphine (15 vol.% PH3/H2) at relatively low temperature. The amorphous Ni–B/SiO2–Al2O3 precursors were synthesized by silver-induced electroless plating. The amorphous precursors and catalysts were characterized by X-ray diffraction, high-resolution transmission electron microscopy, selected area electron diffraction, BET surface area and inductively coupled plasma measurements. The transmission electron micrographs of the Ni2P/SiO2–Al2O3 particles with their size ranging from 60 to 80 nm showed that they were homogeneously dispersed over the SiO2–Al2O3 support. The as-prepared catalysts exhibited an excellent catalytic activity in the hydrodesulfurization (HDS) of dibenzothiophene. # 2007 Elsevier B.V. All rights reserved.

A series of NiO–CaO photocatalysts have been successfully prepared by a precipitation–calcination method. The specimen was characterized by powder X-ray diffraction and UV–vis diffuse reflectance spectra. The UV–vis diffuse reflectance spectra revealed that the NiO–CaO samples exhibited absorptions in a wide visible-light range of 400–600 and 700–800 nm. These results showed that the NiO–CaO samples might possess excellent photocatalytic performances in the wide visible-light region. By using photocatalytic degrading methyl blue as the model reaction, the NiO–CaO samples showed higher photocatalytic activity than those of NiO, CaO, and commercial TiO 2 under visible-light illumination.

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.

Porous and trigonal TiO2 nanoflakes (p-TiO2) 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-TiO2 has an anatase structure. Transmission electron microscopy images indicate that p-TiO2 consists of sheet-like particles with numerous pores about 100 nm 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-TiO2 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.

The relationship between the physicochemical properties and the activity of sonocatalysts is investigated and elucidated in the sonodegradation of amaranth. The sonocatalyts are composed of La(3+) doped TiO(2) synthesized via a sol-gel process. The sonocatalysts are characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopic analysis, UV-Vis absorption spectroscopy, and X-ray photoelectron emission spectroscopy. The sonodegradation products of amaranth are analyzed by UV-Vis absorption spectroscopy. The presence of the La(3+) doped TiO(2) catalysts substantially enhances the sonocatalytic degradation of amaranth in aqueous suspensions. The possible sonocatalytic mechanisms for such are discussed.

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.