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1.
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
2.
A facile, simple and integrated strategy to construct a Pt@TiO 2 core/shell nanoparticle-coated graphene oxide (GO) ternary composite nanostructure (Pt@TiO 2/GO) as an optical limiter with high performance is reported. Pt@TiO 2/GO is prepared by hydrolysis and polycondensation of titanium tetrachloride in the presence of GO to form tetragonal TiO 2 NPs on GO, and then ultrafine Pt nanoparticles (NPs) are anchored on the surface of the TiO 2 NPs. The nonlinear optical (NLO) and optical limiting (OL) properties of Pt@TiO 2/GO are investigated using a nanosecond open-aperture Z-scan technique at 532 nm. Pt@TiO 2/GO exhibits markedly improved NLO and OL performance over that of Pt/GO binary NPs and GO alone. Meanwhile, the NLO performance of the Pt@TiO 2/GO ternary composites nanostructure is significantly better than that of the benchmark molecule C 60 and can be further optimized by tuning the concentration of original reactants in the precursor. The possible mechanisms of this enhancement are the synergistic effect from the combination of nonlinear absorption originating from GO, nonlinear scattering induced in Pt and/or TiO 2 NPs, and efficient charge transfer between TiO 2 NPs and GO sheets, as well as between TiO 2 and Pt NPs. 相似文献
3.
In this paper, we reported a “green” and facile method for one-pot solvothermal synthesis of carbon dots (CDs)/Ag nanoparticles (AgNPs)/titanium dioxide (TiO 2, commercial Degussa P25) ternary nanocomposites with enhanced photocatalytic performance. The characterizations of this ternary photocatalyst were studied at length and our results revealed that the crystalline phase of TiO 2 component remained unchanged after the reaction. While the newborn AgNPs and CDs were tightly attached onto the surface of TiO 2 nanoparticles. The photocatalytic activities of photocatalysts were tested by measurements of photo-degradation on methylene blue (MB) under ultraviolet (UV) and visible light. It was showed that the photocatalytic performance of the ternary photocatalyst was superior to that of single TiO 2 or CDs/TiO 2 binary photocatalyst. It was probably attributed to the synergistic effect of the photoelectrical properties of CDs and the surface plasmon resonance (SPR) effect of AgNPs, which could both enhance the absorption of visible light and hinder the recombination of photogenerated electron-hole pairs. 相似文献
4.
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
5.
Pure TiO 2 and carbon quantum dots (CQDs)-doped TiO 2 nanocomposite (CQDs/TiO 2 nanocomposite) were prepared by a sol-gel approach for photocatalytic removal of Rhodamine B and cefradine. Analyses by Transmission electronmicroscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), UV–visible spectroscopy and X-ray powder diffraction (XRD) confirmed the successful formation of CQDs/TiO 2 heterostructure. The as-prepared TiO 2 and CQDs/TiO 2 composite possessed small particles, spherical-like shape, and anatase crystal form. Meanwhile, Rhodamine B and cefradine were chosen to evaluate the photocatalytic activity of TiO 2 and CQDs/TiO 2 composite. Results revealed that with the facile decoration of CQDs, the absorption of photocatalyst was extended into visible light region and photocatalytic activity was improved in comparison with pure TiO 2. Furthermore, the mechanism for the improvement of the photocatalytic performance of the composites was discussed on the basis of the results. CQDs play an important role in the photocatalytic process, due to their superior ability to extend the visible absorption and produce more electrons and electron–hole pairs for the degradation of pollutants. In all, the paper offers further insights into the development of CQDs/TiO 2 nanocomposite as photocatalyst for the degradation of antibiotics. 相似文献
6.
In the present study, ternary Au-ZnO/rGO nanocomposite was prepared using a modified polyol protocol. The ternary structure was attained by deposition of both gold nanoparticles (AuNPs) and ZnO NPs on the rGO surface. No surfactants or ligands are used in this chemical process. On the other hand, 1,3-propanediol was used as solvent, reducing agent and surfactant to ensure the formation of NPs and inhibit particles accumulation. The XRD data confirm the successful formation of the three materials and the high crystallinity of the as-prepared sample. Moreover, the XPS measurements confirmed the high purity of the nanocomposite. TEM images show the formation of ternary Au/ZnO/rGO nanostructure. However, Au and ZnO NPs exhibited spherical shape with an average size of 20 nm and homogeneously distribution onto the rGO surface. The ternary Au-ZnO/rGO nanocomposite exhibited optical response in both UV and visible region due to the plasmonic properties of AuNPs. The BET data revealed an increase of the surface area of Au-ZnO/rGO nanocomposite compared to bare ZnO and hybrid Au-ZnO NPs which render it a promising system for high photocatalytic activity. The preliminary photodegradation measurements against MB molecules prove the high performance of the ternary Au-ZnO/rGO nanocomposite to decompose pollutant molecules compared to bare ZnO. The observed photocatalytic activity enhancement could be attributed to the apport given by both plasmonic properties of AuNPs and the high surface area of rGO. 相似文献
7.
The novel ternary reduced graphene oxide/1D TiO 2 nanotubes/3D ZnIn 2S 4 microspheres (rGO/TiO 2/ZIS) heterostructured photocatalyst with high-efficiency H 2 production capacity under visible light illumination is designed and prepared in this work. In rGO/TiO 2/ZIS system, the 1D TiO 2 nanotubes are tightly inserted in the interspace of flower-like ZnIn 2S 4 microspheres, which are further covered by rGO, leading to an intimate contact among ZnIn 2S 4, TiO 2 and rGO. The exquisite design of rGO/TiO 2/ZIS makes it possess remarkable superiority in photocatalysis. Firstly, the unique 3D microsphere structure of ZIS increases the surface area and visible light absorption ability caused by their unique hollow structure. More importantly, the matched CB and VB positions between ZIS and TiO 2 contribute to separate photogenerated holes and electrons of ZIS efficiently under visible light; then, the separated electrons on TiO 2 are further transferred to rGO due to the superior-strong electron-attracting ability of rGO. At last, the thoroughly suppressing recombination of photogenerated holes and electrons is achieved by the mutually-reinforcing synergy among ZIS, TiO 2 and rGO, and thus the hydrogen generation capacity of ZIS is significantly enhanced. The H 2 production amount and rate of rGO/TiO 2/ZIS (2.0 wt% rGO and 50 wt% ZIS) after 10 h are 4623 μmol/g and 462.3 μmol/g/h, respectively, which is 71.1 times of pristine TiO 2 and 1.6 times of ZIS under the same condition. The apparent quantum yield of rGO/TiO 2/ZIS (2.0 wt% rGO and 50 wt% ZIS) in 10 h is about 0.6888%. This excellent photocatalytic performance is ascribed to the mutually-reinforcing synergy among ZIS, TiO 2 and rGO, which can be confirmed by X-ray photoelectron spectroscopy, photoelectrochemical measurements and photoluminescence spectrum. Based on the photocatalytic and characterization results, the corresponding mechanism is proposed. 相似文献
8.
A novel kind of loaded photocatalyst of TiO 2/SiO 2/γ‐Fe 2O 3 (TSF) that can photodegrade effectively organic pollutants in the dispersion system and can be recycled easily by a magnetic
field is reported in this paper. The γ‐Fe 2O 3 cores in TiO 2/γ‐Fe 2O 3 are found to reduce the activity of the TiO 2 photocatalyst in the photodegradation of dyes under either UV or visible light irradiation. Addition of a SiO 2 membrane between the γ‐Fe 2O 3 core and the TiO 2 shell weakens efficiently the influence of the γ‐Fe 2O 3 cores on the TiO 2 photocatalytic activity and leads to a highly active and magnetically separable photocatalyst on TSF. Comparison of the photodegradation
processes of dyes under UV and visible irradiation is also carried out.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
Flower-like SnS 2 decorated with MgFe 2O 4 nanoparticles and reduced graphene oxide (rGO) nanosheets were successfully synthesized by a facile solvothermal method. The morphological and crystal structure results confirmed that MgFe 2O 4 nanospheres were uniformly anchored on the surface of SnS 2 flower-like structure with the decoration of rGO nanosheets. The UV–vis diffuse reflectance spectra indicated that the SnS 2–MgFe 2O 4/rGO photocatalyst had a strong visible light absorption. The sample exhibited the highest photocatalytic activity for the degradation of methylene blue under visible light irradiation. The mechanism of improved photocatalytic activity was finally proposed. 相似文献
10.
S–N co-doped anatase nanosized TiO 2 photocatalyst was successfully prepared by simple sol–gel method. The samples were characterized by XRD, XPS, UV–Vis. From the results of UV–Vis, a red shift of the absorption edge was brought out owing to the S and N codoping. XPS and UV–Vis studies revealed that N and S were in situ codoped in the lattice of TiO 2 and the absorbance in visible light region decreased with the calcination temperature increased. The photocatalytic activity was evaluated by the photocatalytic oxidation of penicillin solution under visible light irradiation. The results show that visible-light induced photocatalytic activities of the as-prepared TiO 2 powders were improved by S–N copoing. The high activity of S–N co-doped TiO 2 can be related to the results of the synergetic effects of strong absorption in the UV–Vis region, red shift in adsorption edge. 相似文献
11.
A multifunctional Ag/TiO 2/reduced graphene oxide (rGO) ternary nanocomposite was prepared by a one-step photochemical reaction with TiO 2 and Ag nanoparticles successively deposited on reduced graphene oxide. The structure, morphology, composition, optical, and photoelectrochemical properties of Ag/TiO 2/rGO were investigated in detail. Meanwhile, the ternary nanocomposite possessed much higher adsorption capacity to organic dyes compared with bare TiO 2 and binary Ag/TiO 2, which would help to its use for surface-enhanced Raman scattering detection and photocatalytic degradation. Due to the charge transfer between rGO and organic dyes and enhanced electromagnetic mechanism of Ag, Ag/TiO 2/rGO nanocomposites as surface-enhanced Raman scattering substrates demonstrated dramatically improved sensitivity and good uniformity. The detection limit of rhodamine 6G (R6G) was as low as 10 −9 mol/L, and the relative standard deviation values of the intensities remained below 5%. Most importantly, the synergistic coupling effect of three components extended the photoresponse range and accelerated separation of the electron-hole pairs, leading to greatly improved photocatalytic activity under simulated sunlight. The maximum rate constant ( k, 0.06243 min −1) of Ag/TiO 2/rGO was 50 and four times higher than that of TiO 2 and Ag/TiO 2, respectively. 相似文献
12.
The hybrid rGO-TiO 2/Co 3O 4 nanocomposite was successfully synthesized through co-precipitation method. The structural, morphological, compositional and optical properties of the as synthesized nanocomposite were characterized by X-ray diffraction (XRD), Field Emission scanning electron microscopy (FESEM), energy dispersive X-Ray Spectroscopy (EDS), Fourier transformation infrared spectroscopy (FTIR), UV–visible spectrophotometer (UV–vis) and photoluminescence (PL). XRD, EDS and FTIR confirms the existence of rGO-TiO 2/Co 3O 4 in the prepared nanocomposite. FESEM confirms that the TiO 2/Co 3O 4 nanocomposite are adsorbed on the surface of the rGO. UV–Vis and PL spectra revealed that the absorbance and emission occurred at visible region, which greatly supports the photocatalytic dye degradation through the electron-hole separation. The percentage decolorization of methylene blue dye solution was higher with lesser time compared to crystal violet dye. This result concludes that the commercialization of rGO/TiO 2/Co 3O catalyst may useful for treating various dyes in industries. 相似文献
13.
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
14.
A new photocatalyst was obtained by modification of commercial anatase TiO 2 (Police, Poland) in a pressure reactor in an ethanol atmosphere at 120 °C for 4 h. The photocatalytic activity of the new material was tested during three azo dyes decomposition: monoazo (Reactive Red 198), diazo (Reactive Black 5) and poliazodye (Direct Green 99). The obtained photocatalyst had new bands at 1,440 cm ?1 attributed to CO groups. UV–Vis/DR spectra of the photocatalyst also were changing and had an insignificant decrease in the visible region of the spectra. The amount of hydroxyl radicals produced on carbon-modified TiO 2 was a little higher than for the pristine one. The carbon modification also changes the Freundlich model of dyes adsorption to Langmuir model of adsorption. Additionally, it increases the monolayer capacity of modified TiO 2. As a result we observed a clear increase of the photocatalytic activity of carbon-modified TiO 2 sample. 相似文献
15.
This article reports the synthesis β-SnWO 4–rGO nanocomposite (NC) by a simple solution combustion method followed by low temperature hydrothermal method. The β-SnWO 4–rGO NC has been characterized using various analytical tools such as X-ray diffraction (XRD), Raman spectroscopy, Scanning Electron Microscopy (SEM), High-Resolution Transmission Electron Microscopy (HR-TEM), Ultraviolet-Differential reflectance spectroscopy (UV-DRS). X-ray diffraction pattern shows the formation of cubic structured β-SnWO 4 nanoparticles (NPs) and Raman spectrum shows the presence of rGO in the composite. Transmission Electron Microscopy image shows that SnWO 4 NPs were embedded on the surface of rGO. β-SnWO 4 NPs and β-SnWO 4-rGO NC has been examined as an electrode material for Li-ion battery (LIB). β-SnWO 4 NPs and β-SnWO 4-rGO NC displays an initial discharge capacity of 1351 mAhg ?1 and 1662 mAhg ?1 which is about 23% increase in capacity. Electrochemical performance of β-SnWO 4-rGO NC at different current densities proves that it is one of the good candidates as an electrode material for LIB. β-SnWO 4-rGO NC shows enhanced photocatalytic activity against rose bengal (RB) and methylene blue (MB) compared to pure β-SnWO 4 NPs. 相似文献
16.
In this study, a magnetically recyclable Ni 1-xCd xCe yFe 2-yO 4-rGO (x, y = 0.05) (NCCF-rGO) nanocomposite photocatalyst has been prepared by following a facile in-situ co-precipitation method combined with ultra-sonication means. The as-synthesized magnetically separable NCCF-rGO nanocomposite photocatalyst efficiently degrades methylene blue (MB) dye in comparison to bare Ni 1-xCd xCe yFe 2-yO 4 (x, y = 0.05) (NCCF) nanoparticles (NPs) under visible light irradiation. The photo-degradation rate of MB with NCCF-rGO was ~9 times higher than NCCF nanoparticles (NPs). This enhanced photocatalytic performance of NCCF-rGO photocatalyst was due to the presence of reduced graphene oxide, which greatly help in production of photoactive species by reducing the rate of electro-hole pair recombination. The role of photoactive species that were responsible for the photocatalytic degradation of methylene blue has also been investigated. The as-synthesized NCCF-rGO photocatalyst expressed superb chemical stability and photocatalytic activity even after seven cycle runs. Moreover, the NCCF-rGO nanocomposite worked at all pH values and showed good acid resistance. In particular, the as-synthesized NCCF-rGO photocatalyst could be collected for the next cycle run by simply applying an external magnetic field. Hence, the NCCF-rGO nanocomposite could have potential use in organic dyes contained wastewater treatment. 相似文献
17.
The aim of this research is to enhance the photocatalytic activity of TiO 2 nanoparticles for the UV–visible light by multiple-doping with Iridium, carbon and nitrogen. The tridoped TiO 2 photocatalyst were prepared by wet chemical method, and characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet-visible light diffuse reflection spectroscopy and room temperature photoluminescence spectroscopy. Besides, the photocatalytic H 2 evolution performance of Ir-C-N tridoped TiO 2 under UV–visible light irradiation was evaluated. It was found that Ir existed as Ir 4+ by substituting Ti in the lattice of TiO 2; meanwhile, C and N were also incorporated into the surface of TiO 2 nanoparticles in interstitial mode. Meanwhile, Ir-C-N tridoping extended the absorption of TiO 2 into the visible light region and narrowed its band gap to ~3.0 eV, resulting in enhanced photocatalytic H 2 evolution under UV–visible light irradiation. This could be attributed to narrow band gap and proper electronic structure of TiO 2 after Ir-C-N tridoping. 相似文献
18.
In this research, novel ternary Ag/αFe 2O 3-rGO nanocomposites with various contents of GO were synthesized via a facile one-pot hydrothermal method. Ag/αFe 2O 3-rGO nanocomposites were characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectrometer (EDX), photoluminescence (PL) spectroscopy, and Fourier transform infrared (FTIR). The results showed that hematite nanoparticles and Ag nanoparticles were well decorated on the graphene surface. Photocatalytic activity of Ag/αFe 2O 3-rGO ternary nanocomposites and pure Ag/αFe 2O 3 was investigated for photodegradation of Congo red dye solution as a model pollutant under UV light irradiation. The ternary nanocomposite with 1.8?mg/ml GO aqueous solution concentration shows higher degradation efficiency under UV light irradiation than the pure Ag/αFe 2O 3 and the nanocomposites with other GO aqueous solution concentrations. It was observed that the adsorption of the dyes on the nanocomposites surface is dependent on the graphene content due to a decrease in the recombination rate, particles size, and increase charge carrier transfer. The results show that the Ag/αFe 2O 3-rGO nanocomposite can be used as an excellent photocatalytic material for degradation of Congo red dye in wastewater. A possible photocatalytic mechanism was proposed for degradation of Congo red dye. 相似文献
19.
BACKGROUND: This research investigated the effect of platinum (Pt) on the reactivity of tungsten oxide (WO 3) for the visible light photocatalytic oxidation of dyes. RESULTS: Nanocrystalline tungsten oxide (WO 3) photocatalysts were synthesised by a sol‐gel process and employed for the photocatalytic degradation of Methyl Orange under visible light. For comparison commercial bulk WO 3 materials were also studied for the same reaction. These materials were fully characterised using X‐ray diffraction (XRD), UV‐visible diffuse reflection spectroscopy and transmission electron microscopy (TEM). The photocatalytic oxidation of iso‐propanol was used as a model reaction to follow the concomitant reduction of molecular oxygen. No reactions occured in the absence of platinum, which is an essential co‐catalyst for the multi‐electron reduction of oxygen. The platinised WO 3 catalysts were stable for multiple oxidation–reduction cycles. The results from the catalytic activity measurements showed that platinised nanocrystalline WO 3 is a superior oxidation photocatalyst when compared with bulk WO 3. Methyl Orange was completely decolourised in 4 h. CONCLUSIONS: The enhanced performance of nanocrystalline Pt‐WO 3 is attributed to improved charge separation in the nanosized photocatalyst. Platinum is an essential co‐catalyst to reduce oxygen. This photocatalyst could be applied to the treatment of organic pollutants in wastewater, with the advantage of using visible light compared with the widely studied TiO 2, which requires UV light. Copyright © 2011 Society of Chemical Industry 相似文献
20.
Monitoring the contents of organic dyes in real-time is crucial for the valuation of photocatalyst performance. To achieve this, a method of detecting organic dyes was designed based on color variations by using Ag nanoparticle modified TiO 2 nanotubes (Ag/TiO 2) as photocatalysts. The obtained Ag/TiO 2 photocatalyst possesses strong visible-light absorption, and 1.0% Ag/TiO 2 exhibited the best performance under UV and simulated sunlight. The investigation indicates that the photocatalytic activity of TiO 2 nanotubes is greatly improved by the modification with silver. Moreover, the photodegradation intermediates and pathways are demonstrated by trapping experiments and density functional theory calculations. To quantitatively determine the concentration of methyl orange, a partial least squares model was built using RGB values and the concentration of a methyl orange solution. This finding provides a new idea to fabricate a sensor for point-of-care test of organic dyes in the field of environmental applications. 相似文献
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