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1.
Cerium dioxide was prepared by the precipitation method and found to be an efficient photocatalyst to degrade azodyes under visible light irradiation. Nonbiodegradable azodyes acid orange 7 (AO7) was selected as modal target to examine the photocatalytic activity of CeO 2. AO7 could be efficiently degraded in aqueous suspension of CeO 2 under visible light illumination. The catalyst was characterized by X-ray diffraction (XRD), N 2 sorption, transmission electron microscopic image (TEM) and UV/vis absorption spectrum techniques. AO7 solution was quickly decolorized and partly mineralized under visible light irradiation with existing CeO 2. The photodegradation rate of this azodye catalyzed by CeO 2 is much faster than those occurring on commercial titania (Degussa P25) under otherwise identical conditions of visible light irradiation. Experiments were conducted to examine the adsorption mode of acid orange 7 on CeO 2 and adsorption capacity at different pH values. The possible degradation pathway has been proposed for the photocatalytic degradations by using certain radical scavengers and gas chromatography–mass spectrometry (GC–MS) to determine intermediates. The enhanced photoactivity of the lanthanide oxide CeO 2 was attributed to the superior adsorption capacity and special 4f electron configuration. 相似文献
2.
Developing a photocatalyst system for the conversion of solar energy to electric energy or chemical energy is a topic of great interest with fundamental and practical importance. The semiconductor catalysts, such as InTaO 4, have been extensively used for water splitting under visible light irradiation. However, it has not been used for photoreduction of carbon dioxide with water. InTaO 4 was synthesized by solid-state reaction. NiO was added by incipient-wetness impregnation method as the cocatalysts. The catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet–visible spectroscopy (UV–Vis) and X-ray photoelectron spectroscopy (XPS). The photocatalytic reduction was carried out in a Pyrex reactor under visible light illumination using 500 W halogen light as the light source. The band gap of InTaO 4 was estimated, from UV–Vis spectrum, to be 2.6 eV, showing that these catalysts have ability to reduce CO 2 into methanol. The effects of the NiO cocatalyst and pretreatment process on the photocatalytic reduction of the catalyst to methanol were investigated. The methanol yield increased with the amount of NiO cocatalyst. The reduction–oxidation pretreatment had a positive effect on the catalyst. 相似文献
3.
The photocatalytic preferential oxidation of CO with O 2 in the presence of H 2 (photo-PROX) was found to proceed efficiently on the NiO-loaded TiO 2 (NiO/TiO 2) catalyst under UV light irradiation at 293 K. NiO/TiO 2 exhibited higher CO conversion as well as CO 2 selectivity for a photo-PROX reaction than the original unloaded TiO 2 (P-25). Various spectroscopic investigations have revealed that the small NiO clusters formed on TiO 2 play an important role in the enhancement of CO oxidation activity in this reaction. 相似文献
4.
Here we report the facile synthesis of Ag/Ag 2O heterostructures, which exhibit excellent solar full spectrum (UV, visible and near-infrared) photocatalytic activity and an enhanced photoelectrochemical (PEC) performance under irradiation of near-infrared light. The improved photocatalytic property and PEC performance originated from the synergistic effect on the narrow band gap of Ag 2O, plasmon enhancement of metallic Ag in-situ reduced from Ag 2O, and metal-semiconductor (Ag-Ag 2O) Mott-Schottky heterojunction. 相似文献
5.
Ag 3PO 4 was synthesized with the assistance of N, N-dimethylformamid (DMF) and urea for high performance photocatalysis. The photocatalytic activity of the as-synthesized samples was evaluated by photodegrading rhodamine B (Rh B) under visible light irradiation. As a result, the optimal Ag 3PO 4 synthesized with the assistance of DMF and urea exhibited enhanced photocatalytic activity for Rh B degradation under visible light irradiation. DMF and urea play vital roles in improving the photocatalytic activity of Ag 3PO 4. This study could provide a new perspective for the controllable synthesis of Ag 3PO 4. 相似文献
6.
The 1D Ag 3PO 4 sensitized SrTiO 3 nanowires are prepared by simple route of electrospinning-in situ deposition technique. The results of the thermogravimetry (TG), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive Spectrometer (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV–Visible diffuse reflectance spectroscopy (UV–Vis) indicate that the Ag 3PO 4 nanoparticles has been deposited on the surface of the SrTiO 3 nanowires successfully. Experimental results showed that compared with pure SrTiO 3, the as-prepared 1D Ag 3PO 4 sensitized SrTiO 3 nanowires exhibit obvious enhancement of photocatalytic performance and stability. Especially, the Ag 3PO 4/SrTiO 3 (3AS sample) had a satisfactory photocatalytic activity for degrading methylene blue (MB) more than 98% under visible light irradiation. As to pure SrTiO 3 and Ag 3PO 4, only 9.8% and 49% of MB was decomposed after 35?min irradiation respectively. Furthermore, the mechanism of the enhancing photocatalytic activity could be ascribed to the nano-heterojunction of the Ag 3PO 4/SrTiO 3, the visible light response of the Ag 3PO 4, and the 1D structure of the nanowires. 相似文献
7.
Introducing magnetic metal onto semiconductor materials has been proven to be an attractive strategy for enhancing the photocatalytic activity in the visible region. In this work, ternary heterostructure magnetic semiconductor photocatalyst RGO/ZnFe2O4/Ag2WO4 was successfully synthesized through a simple hydrothermal method and was evaluated by photodegradation of Rhodamine B (RhB) under visible light irradiation. The composition, structure, morphology, and optical absorption properties of the as-prepared photocatalyst were investigated by XRD, FT-IR, SEM, and UV–Vis DRS, respectively. It was found that the photocatalytic activity under visible light irradiation was in the order of RGO/ZnFe2O4/Ag2WO4?>?ZnFe2O4?>?Ag2WO4?>?RGO/ZnFe2O4 and RGO/ZnFe2O4/Ag2WO4. The enhancement of photocatalytic performance could be attributed to the reduced graphene oxide sheets can function as an electron collector and transporter to lengthen the lifetime of the charge carriers, improving the whole photocatalytic activity. The reaction kinetics, possible degradation pathway, and catalyst stability, as well as the roles of ZnFe2O4 and Ag2WO4 in photoreaction, were comprehensively studied. The obtained results indicate that the prepared magnetic and effective catalytic materials could be potentially applied in environmental organic pollutants purification. 相似文献
8.
The present work demonstrates a facile route for preparing LaFeO 3/rGO nanocomposites comprising of metal oxide nanoparticles and graphene. Structural, morphology, optical and photocatalytic studies of the samples were characterized using powder X-ray diffraction (XRD), FT-IR, Raman, high resolution scanning electron microscopy (HRSEM), high resolution transmission electron microscope (HRTEM), atomic force microscopy (AFM), thermogravimetry (TGA), X-ray photoelectron spectroscopy, UV–visible and photocatalytic. LaFeO 3/rGO nanocomposites believed as an effective photocatalyst for the degradation of methyl orange (MO) dye under visible light irradiation. The inclusion of carbon enhances the light absorption of LaFeO 3, resulting in the enhanced photocatalytic activity of the nanocomposite. The degradation of MO dye under visible light source was completely achieved using LaFeO 3/rGO as a catalyst. 相似文献
9.
TiO 2 porous ceramic/Ag–AgCl composite was prepared by incorporating AgCl nanoparticles within the bulk of TiO 2 porous ceramic followed by reducing Ag + in the AgCl particles to Ag 0 species under visible light irradiation. The porous TiO 2 ceramic was physically robust and chemically durable, and the porous structure facilitated the implantation of AgCl NPs. Compared with the bare TiO 2 ceramic, TiO 2 porous ceramic/Ag–AgCl composite exhibited higher photocatalytic performance for the degradation of MO and RhB under visible light irradiation. The reaction rate constants k of MO and RhB degradation over TiO 2 porous ceramic/Ag–AgCl composite was respectively 6.25 times and 3.62 times higher than those recorded over the bare TiO 2 porous ceramic. The photocatalytic activity showed virtually no decline after four times cyclic experiments under visible light irradiation. Scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, UV–Vis diffuse reflectance spectroscopy, photoluminescence spectra and X-ray photoelectron spectroscopy were used to characterize the TiO 2 porous ceramic/Ag–AgCl composite. 相似文献
10.
The BiOCl/Ag 3PO 4 composites have been prepared via a facile and reproducible route. In the composite, Ag 3PO 4 particles are deposited on the surface of plates of BiOCl. Among the as‐prepared samples, the ultraviolet (UV) and visible light photocatalytic reaction rates of BiOCl/Ag 3PO 4 composite with the ratio of 1:0.1 are about 4.4 times and 4.5 times than that of pure BiOCl, respectively. Overall, the BiOCl/Ag 3PO 4 composites not only show highly enhanced visible light photocatalytic activity but also exhibit highly improved UV photocatalytic activity, which could find enormous potential application in addressing environmental protection issues utilizing solar energy effectively. 相似文献
11.
A novel NiTiO 3/Ag 3VO 4 composite with type-II band alignment was prepared using a modified Pechini/precipitation method. The FESEM image of the NiTiO 3/Ag 3VO 4 heterostructure reveals the dispersion of small NiTiO 3 particles on the Ag 3VO 4 surfaces, indicating the close interfacial connection between NiTiO 3 and Ag 3VO 4. The heterojunction shows remarkably higher photocatalytic activity than pure NiTiO 3 and Ag 3VO 4 due to an increase in light harvesting efficiency and an efficient electron–hole separation being induced by the suitably matching conduction and valence band levels. Based on the VB-XPS and UV–vis DRS results, a possible electron–hole transfer mechanism at the NiTiO 3/Ag 3VO 4 interface is proposed. 相似文献
12.
WO 3 and bi-layer WO 3/TiO 2 coatings of different catalyst loadings were electrosynthesized on stainless steel 304 (SS) substrates from acidic aqueous
solutions by single-step and consecutive steps potentiostatic cathodic deposition. The resulting WO 3/SS and TiO 2/WO 3/SS photoelectrodes were screened for their photoresponse under ultraviolet (UV) and visible light illumination by photovoltammetry
and photoamperometry in sulphate solutions, in the absence and presence of 4-chlorophenol (4-CP). They were also evaluated
for bulk photo-oxidation of 4-CP under constant potential, in the voltage range determined on the basis of the photovoltammetric
tests. The optimal weight ratio between TiO 2 and WO 3 was also established, ensuring the best performance of these photoelectrodes for the photooxidation of 4-CP under UV and
visible light irradiation. 相似文献
13.
Visible-light-induced titania/sulfanilic acid nano-composite photocatalysts were prepared and characterized by FTIR, XPS, UV-vis, XRD, and SEM. The results indicate that the formation of Ti-O-S bonds after the modification of P25 TiO 2 nanoparticles with sulfanilic acid ligands extends the photoresponse of the photocatalyst from the UV to the visible range. The photocatalytic activity of the nano-composite photocatalyst was examined by degrading Congo red under visible light, in which its effecting factors such as irradiation time, catalyst dosage, solution pH and the addition of H 2O 2, were investigated in detail. The possible mechanism of photocatalytic degradation under visible irradiation has been also presented. 相似文献
14.
MgFe 2O 4/Ag 3VO 4 composite photocatalysts were synthesized by a milling–calcining method. The results of Rhodamine B (RhB) photodegradation showed that the MgFe 2O 4/Ag 3VO 4 composite exhibited enhanced photodegradation activity under visible-light irradiation. The 0.2 wt.% MgFe 2O 4/Ag 3VO 4 calcined at 573 K exhibited the optimal photocatalytic behavior. Its maximum degradation rate was 5.4 times higher than that of Ag 3VO 4. Moreover, transient photocurrent-time was also investigated. Based on the results of the characterizations, the mechanism of enhanced photocatalytic activity is discussed. 相似文献
15.
Nanosized particles of strontium bismuth vanadate SrBi 3VO 8 were prepared via the Pechini method on the base of citrate‐complexation route. The samples were characterized using X‐ray powder diffraction (XRD), scanning electron microscope (SEM), energy dispersive X‐ray spectra (EDX), X‐ray photoelectron spectroscopic (XPS), and UV–vis absorption spectrum. This bismuth‐containing vanadate presents an efficient absorption in the UV–visible light wavelength region with a narrow band‐gap energy of 2.36 eV and an indirect allowed electronic transition. It is well‐known that hybridization of the 6 s and 6 p orbitals of Bi 3+ could result in lone electron pair and yield some very interesting properties. The photocatalytic activities of SrBi 3VO 8 nanoparticles were evaluated by the photodegradation of methylene blue (MB) under visible light irradiation in air atmosphere. These results indicate that SrBi 3VO 8 could be a potential photocatalyst driven by visible light. To understand the charge generation and separation process, the luminescence as well as the decay lifetimes was investigated in the same samples for photocatalysis. 相似文献
16.
The present work is focused on the preparation of hybrid ZnO/TiO 2/Ag 2O nanocomposite for enhanced photocatalytic activity. The resultant samples are characterized by using XRD, SEM, EDX, HR-TEM, UV-DRS, BET and XPS techniques. X-ray diffraction analysis indicates the co-existence of wurtzite, anatase and cubic phases in ZnO/TiO 2/Ag 2O nanocomposite. The band gap energy value of the photocatalyst is 3.39 eV, which has been evidenced from UV–visible diffuse reflectance spectroscopy measurements. Photocatalytic degradation of methylene blue dye has been investigated by using UV–visible spectrophotometer. From the result, it has been concluded that ZnO/TiO 2/Ag 2O nanocomposite has proven to be an efficient photocatalyst under UV irradiation when compared to that of mono and binary oxide systems. Further, the possible photodegradation mechanism is proposed to support the enhancement of photocatalytic activity towards degradation of dyes. 相似文献
17.
Selective oxidation of benzene with H 2O 2 to phenol has been developed using a novel Fe(III) complex bearing 5-sulfosalicylic acid ligands immobilized alumina catalyst under visible light irradiation. The catalyst activity was evaluated by the photooxidation of benzene to phenol. The results indicate the best result with 100% conversion of benzene and 27.64% selectivity for phenol at low catalyst loading (0.7 mmol/g alumina). The catalyst was used for at least 4 cycles without any appreciable loss of activity. 相似文献
18.
Novel carbon black (CB)/Ag 3PO 4 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/Ag 3PO 4 was evaluated through methyl orange degradation experiments under visible light irradiation. The CB/Ag 3PO 4 showed higher photocatalytic activity than pure Ag 3PO 4. 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/Ag 3PO 4 was 1.6 times that of Ag 3PO 4. And the results of the cyclic experiment show that the photocatalyst has good stability. Moreover, the mechanism about the photocatalytic activity of CB/Ag 3PO 4 compounds was investigated. In this photocatalytic reaction, ?OH was the major active substrate responsible for the visible-light-driven degradation. 相似文献
19.
The photocatalytic degradation of a commercial azo-reactive textile dye, Remazol Red F-3B, has been investigated in a batch slurry reactor using semiconductor catalysts like, ZnO and TiO 2, and two UV sources emitting mainly at 254 and 365 nm. Non-irradiated catalysts and non-catalyzed UV irradiation have negligible effect on the dye degradation. Initial pH, dye concentration, light power and catalyst loading as well as the catalyst type and UV wavelength are considered as process variables. The results showed that decolorization and TOC removal efficiencies of ZnO are higher under 365 nm UV. On the other hand, when two photocatalysts are compared, the decolorization performance of ZnO is higher than TiO 2 under 365 nm UV , while TiO 2 performs better under 254 nm UV. Furthermore, from the TOC removal point, TiO 2 performs better than ZnO irrespective of the UV wavelength. TiO 2 irradiated under 254 nm UV degrades successfully both benzene and naphthalene derivatives. 相似文献
20.
A visible light active photocatalyst, Ag/TiO 2/MWCNT was synthesized by loading of Ag nanoparticles onto TiO 2/MWCNT nanocomposite. The photocatalytic activity of Ag/TiO 2/MWCNT ternary nanocomposite was evaluated for the degradation of methylene blue dye under UV and visible light irradiation. Ag/TiO 2/MWCNT ternary nanocomposite exhibits (~9 times) higher photocatalytic activity than TiO 2/MWCNT and (~2 times) higher than Ag/TiO 2 binary nanocomposites under visible light irradiation. The enhancement in the photocatalytic activity is attributed to the synergistic effect between Ag nanoparticles and MWCNT, which enhance the charge separation efficiency by Schottky barrier formation at Ag/TiO 2 interface and role of MWCNT as an electron reservoir. Effect of different scavengers on the degradation of methylene blue dye in the presence of catalyst has been investigated to find the role of photogenerated electrons and holes. Simultaneously, the Ag/TiO 2/MWCNT shows excellent photocatalytic stability. This work highlights the importance of Ag/TiO 2/MWCNT ternary nanocomposite as highly efficient and stable visible-light-driven photocatalyst for the degradation of organic dyes. 相似文献
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