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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.
This work explores the effect of ternary nanostructure for the enhanced photocatalytic degradation of pollutants and dyes. One-pot solvothermal-assisted approach was used for producing nanosized Pt@TiO2 hybrid nanoparticles (NPs) decorated on reduced graphene oxide (rGO) layers. The microstructure, morphology, chemical composition, and optical absorption of the designed photocatalyst was successfully characterized (using XRD, TEM, Raman, UV–visible absorption spectra, and XPS techniques). The ternary Pt@TiO2-rGO photocatalyst consist of monodisperse quasi-spherical Pt@TiO2 NPs with an average size of 11 nm deposited on the rGO nanosheets. Furthermore, Pt@TiO2-rGO was further investigated for the photodegradation of pesticide and dyes under UV and visible light. The ternary Pt@TiO2-rGO photocatalyst proved a significant improvement on the photodecomposition of pollutants compared to hybrid Pt@TiO2. The Pt@TiO2-rGO photocatalyst was found to show seven- and threefold increase in the photocatalytic activity compared to TiO2 and Pt@TiO2 NPs, respectively which resulted from the high surface area of rGO and as well as the strong Pt/TiO2/rGO interactions which ensured excellent properties of charge separation. On the other hand, the ternary photocatalyst exhibited very good recycle and reuse capacity up to five cycles. 相似文献
3.
Effective design and fabrication of novel visible light-oriented photocatalysts is an existing challenging task that requires further dedicated efforts, and it has been always a main concern among the scientific community. This study deals with the design and fabrication of an extremely active and ultrafast ternary photocatalyst based on Ag nanoparticles, polypyrrole doped carbon black (PPy-C) and mesoporous TiO 2 (m-TiO 2). Sol-gel methodology along with sonication and photodeposition routes have been employed for the successful creation of the ternary framework. Ternary photocatalyst composed of uniform spherical titania nanoparticles (10–15 nm in size) perfectly intermingled with the polymeric linkage of PPy-C. Fruitful creation of unique trio photocatalyst between AgNPs, PPy-C and m-TiO 2 was confirmed by XPS and XRD. FTIR analysis further supports the development of nanocomposite photocatalyst. TEM analysis showed uniform spherical m-TiO 2 nanoparticles (10–15 nm in size) covered by PPy-C with compact nodes like appearance interlocked very well among each other. The newly developed Ag@PPy-C/m-TiO 2 ternary photocatalyst exhibited band gap energy in desired visible range of spectra. The photocatalytic efficiency for all created photocatalysts has been evaluated taking Imidacloprid (insecticide derivative) and methylene blue (MB) dye as target pollutants. The novel Ag@PPy-C/m-TiO 2 photocatalyst produced astonishing results with ultrafast removal of both Imidacloprid as well MB dye under visible light irradiation. The newly created ultrafast Ag@PPy-C/m-TiO 2 photocatalyst has removed 96.0% of the insecticide Imidacloprid in only 25 min with almost ? 2.65 times more efficient than bare m-TiO 2 towards the removal of insecticide derivative. The present report offers a highly encouraging and vastly talented Ag@PPy-C/m-TiO 2 ternary photocatalyst, enabling the ideal management of extremely lethal and notorious chemicals. 相似文献
4.
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
5.
Photocatalytic reduction of carbon dioxide (CO 2) into valuable hydrocarbon such as methane (CH 4) using water as reducing agent is a good strategy for environment and energy applications. In this study, a facile and simple sol-gel method was employed for the synthesis of metal (Cu and Ag) loaded nanosized N/TiO 2 photocatalyst. The prepared photocatalysts were characterized by X-ray diffraction, transmission electron microscopy, BET Surface area analyzer, X-ray photoelectron spectroscopy and UV–vis diffuses reflectance spectroscopy. The photocatalytic conversion of CO 2 into methane was carried out under visible light irradiation (λ≥420 nm) by prepared photocatalysts in order to evaluate the photocatalytic efficiency. The results demonstrate that Ag loaded N/TiO 2 showed enhanced photocatalytic performance for methane production from CO 2 compared to other Cu–N/TiO 2, N/TiO 2 and TiO 2 photocatalysts. The improvement in the photocatalytic activity could be attributed to high specific surface area, extended visible light absorption and suppressed recombination of electron – hole pair due to synergistic effects of silver and nitrogen in the Ag–N/TiO 2 photocatalyst. This study demonstrates that Ag–N/TiO 2 is a promising photocatalytic material for photocatalytic reduction of CO 2 into hydrocarbons under visible light irradiation. 相似文献
6.
Rational design of semiconductor membrane photocatalyst with good mechanical flexibility and excellent photocatalytic activity is of significance for environmental remediation. Herein, flexible Ag@ZnO/TiO 2 fibrous membranes with hierarchical nanostructures were fabricated through combining a simple electrospinning method and subsequent hydrothermal reaction and photodeposition process. In the ternary nanocomposite, ZnO nanorods were firmly anchored onto TiO 2 nanofibers, while Ag nanoparticles were evenly decorated on the surface of both ZnO and TiO 2. Benefiting from the improved light absorption, large surface area, and effective charge separation, the resultant Ag@ZnO/TiO 2 membranes displayed superior photocatalytic degradation efficiency of 91.6% toward tetracycline hydrochloride within 1 h, and also exhibited prominent antibacterial activity with a 6.5 log inactivation of E. coli after 1 h simulated solar light exposure. Significantly, the membrane photocatalyst still preserved structural integrity and mechanical flexibility after utilization. This study provides an alternative approach for designing and synthesizing flexible TiO 2-based membrane photocatalysts toward high-efficiency water purification. 相似文献
7.
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
8.
By integrating strongly plasmonic Au nanoparticles with strongly catalytic TiO 2, we observe enhanced photocatalytic decomposition of methyl orange under visible illumination. Irradiating Au nanoparticles at their plasmon resonance frequency creates intense electric fields, which can be used to increase electron–hole pair generation rate in semiconductors. As a result, the photocatalytic activity of large bandgap semiconductors, like TiO 2, can be extended into the visible region of the electromagnetic spectrum. Here, we report a 9-fold improvement in the photocatalytic decomposition rate of methyl orange driven by a photocatalyst consisting of strongly plasmonic Au nanoparticles deposited on top of strongly catalytic TiO 2. Finite-difference time-domain (FDTD) simulations indicate that the improvement in photocatalytic activity in the visible range can be attributed to the electric field enhancement near the metal nanoparticles. The intense local fields produced by the surface plasmons couple light efficiently to the surface of the TiO 2. This enhancement mechanism is particularly effective because of TiO 2’s short exciton diffusion length, which would otherwise limit its photocatalytic efficiency. Our electromagnetic simulations of this process suggest that enhancement factors many times larger than this are possible if this mechanism can be optimized. 相似文献
9.
AgBr@Ag/TiO 2 core–shell photocatalysts were fabricated by a facile green route. TiO 2 was uniformly coated on the surface of cubic AgBr, making AgBr@Ag/TiO 2 core–shell photocatalyst show excellent hydrothermal stability. Beneficial from that Ag nanoparticles and AgBr can respond to visible light and core–shell structure can effectively separate the photogenerated electrons and holes, AgBr@Ag/TiO 2 core–shell composites exhibited outstanding visible light photocatalytic activity for the degradation of acid orange 7. The activity of AgBr@Ag/TiO 2 is related to the thickness of TiO 2 shell, and the optimal shell thickness for obtaining the highest activity is 10 nm. 相似文献
10.
Sr 2TiO 4 is a promising photocatalyst for antibiotic degradation in wastewater. The photocatalytic performance of pristine Sr 2TiO 4 is limited to its wide bandgap, especially under visible light. Doping is an effective strategy to enhance photocatalytic performance. In this work, Nb/N co-doped layered perovskite Sr 2TiO 4 (Sr 2TiO 4:N,Nb) with varying percentages (0–5 at%) of Nb were synthesized by sol-gel and calcination. Nb/N co-doping slightly expanded the unit cell of Sr 2TiO 4. Their photocatalytic performance towards antibiotic (tetracycline) was studied under visible light (λ > 420 nm). When Nb/(Nb + Ti) was 2 at%, Sr 2TiO 4:N,Nb(2%) shows optimal photocatalytic performance with the 99% degradation after 60 min visible light irradiation, which is higher than pristine Sr 2TiO 4 (40%). The enhancement in photocatalytic performance is attributed to improving light absorption, and photo-generated charges separation derived from Nb/N co-doping. Sr 2TiO 4:N,Nb(2%) shows good stability after five cycles photocatalytic degradation reaction. The capture experiments confirm that superoxide radical is the leading active species during the photocatalytic degradation process. Therefore, the Nb/N co-doping in this work could be used as an efficient strategy for perovskite-type semiconductor to realize visible light driving for wastewater treatment. 相似文献
11.
A series of calcined hydrotalcite/TiO 2-Ag (HTC/TiO 2-Ag) composites with different silver (Ag) contents were successfully prepared and investigated as a catalyst for the photodegradation of phenol using UV–vis light (λ>300 nm). The Ag nanoparticles were deposited on the surface of TiO 2 (TiO 2-Ag) through photodeposition method. The TiO 2-Ag nanoparticles were supported on hydrotalcite (HT) by the co-precipitation method at variable pH (HT/TiO 2-Ag), and then calcined at 500 °C to obtain the HTC/TiO 2-Ag composites. The composites were characterized by inductively coupled plasma mass spectrometry (ICP-MS), N 2 adsorption/desorption (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), and diffuse reflectance spectra (DRS). Results show that there is an optimum silver ratio to obtain the highest photocatalytic performance in the HTC/TiO 2-Ag photocatalyst which is 2 wt%, and is assigned as HTC/TiO 2-Ag(2). The association of silver nanoparticles on TiO 2 enhanced photocatalytic activity of the bare semiconductor composite. Only 56% of phenol was photodegraded when photodegradation was performed with HTC/TiO 2, whereas ~100% was photodegraded using HTC/TiO 2-Ag(2). The data gathered from the photocatalytic degradation of phenol were successfully fitted to Langmuir-Hinshelwood model, and can be described by pseudo-first order kinetics. The results showed the HTC/TiO 2-Ag(2) as efficient photocatalyst, low cost, separable from solution by sedimentation, and reusable. The superior performance of HTC/TiO 2-Ag(2) composite photocatalyst may be attributed to the synergic catalytic effect between silver and TiO 2, dispersion of TiO 2-Ag(2) nanoparticles supported on calcined hydrotalcite, and the calcined hydrotalcite like photocatalyst. 相似文献
12.
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
13.
Mesoporous TiO 2 frameworks incorporated with diverse percentages of Cr 2O 3 nanoparticles (NPs) were achieved through the one-step sol-gel approach for photocatalytic H 2 evolution under visible-light exposure. The obtained isotherms could be classified as type IV, indicating mesopore 2D-hexagonal symmetry. The H 2 evolution rate over mesoporous Cr 2O 3/TiO 2 photocatalyst was observably promoted employing glycerol as a sacrificial agent, providing a comparatively high H 2 yield of 14300 μmolg ?1. The highest photocatalytic efficiency was achieved with an optimal 4% Cr 2O 3/TiO 2 photocatalyst, and the evolution rate was enhanced 1430-fold compared to pristine TiO 2. The eminent photocatalytic performance of mesoporous Cr 2O 3/TiO 2 was ascribable to different key factors such as the narrow bandgap, wide visible light photoresponse, Cr 2O 3 as photosensitizer, synergistic effect and high surface area. The recycle tests for five times over synthesized photocatalyst revealed excellent durability and stability without loss in H 2 evolution. The photocatalytic mechanisms for H 2 evolution over Cr 2O 3/TiO 2 photocatalyst were proposed according to the photocurrent transient and photoluminescence measurements and photocatalytic H 2 evolution results. 相似文献
14.
We fabricated novel ternary nanocomposites through integration of C-dots (carbon dots), BiOCl, and nanosheets of graphitic carbon nitride (g-C 3N 4 nanosheets) by a cost-effective route. The fabricated photocatalysts were subsequently characterized by XRD, EDX, TEM, HRTEM, XPS, FT-IR, UV-vis DRS, TGA, BET, and PL methods to gain their structure, purity, morphology, optical, textural, and thermal properties. In addition, the degradation intermediates were identified by gas chromatography-mass spectroscopy (GC-MS). Photocatalytic performance of the synthesized samples was studied by photodegradations of three cationic (RhB, MB, and fuchsine), one anionic (MO) dyes, one colorless (phenol) pollutant and removal of an inorganic pollutant (Cr(VI)) under visible light. It was revealed that the ternary nanocomposite with loading 20% of BiOCl illustrated superlative performances in the selected photocatalytic reactions compared with the corresponding bare and binary photocatalysts. Visible-light photocatalytic activity of the g-C 3N 4 nanosheets/CDs/BiOCl (20%) nanocomposite was 42.6, 27.8, 24.8, 20.2, and 15.9 times higher than the pure g-C 3N 4 for removal of RhB, MB, MO, fuchsine, and phenol, respectively. Likewise, the ternary photocatalyst showed enhanced activity of 15.3 times relative to the g-C 3N 4 in photoreduction of Cr(VI). Moreover, the ternary nanocomposite exhibited excellent chemical stability and recyclability after five cycles. Finally, the mechanism for improved photocatalytic performance was discussed based on the band potential positions. 相似文献
15.
采用溶剂热法制备钨酸铋/石墨烯(Bi_2WO_6/RGO)光催化剂,然后利用光还原法将Au纳米颗粒沉积于该二元光催化剂表面,制备出Au/Bi_2WO_6/RGO三元复合可见光催化剂。运用X射线衍射(XRD)、紫外可见漫反射吸收光谱(UV-Vis DRS)和透射电镜(TEM)对催化剂的晶体结构、光吸收性能、形貌性能进行了分析表征。以罗丹明B (Rh B)为模拟污染物,评价了该催化剂的可见光催化性能。结果表明,RGO和Au纳米颗粒的引入,增强了Bi_2WO_6可见光吸收,同时抑制了光生载流子的复合,从而提高Bi_2WO_6可见光催化降解RhB的性能。 相似文献
16.
Silver nanoparticles doped on titanium oxide (TiO 2) were produced by laser-liquid interaction of silver nitrate (AgNO 3) in isopropanol. Characteristics of Ag/TiO 2 (Ag doped TiO 2) nanoparticles produced by the methods presented in this article were investigated by XRD, TEM, SEM, EDX, and UV-Vis. From the UV-Vis measurements, the absorption of visible light of the Ag/TiO 2 photocatalysts was improved (additional absorption at longer wavelength in visible light region) obviously. The photocatalytic efficiency of Ag/TiO 2 was tested by the degradation of methylene blue (MB) in aqueous solution. A maximum of 82.3% MB degradation is achieved by 2.0 wt% Ag/TiO 2 photocatalyst under 2 h illumination with a halogen lamp. 相似文献
17.
BACKGROUND: Semiconductor TiO 2 has been investigated extensively due to its chemical stability, nontoxicity and inexpensiveness. However, the wide band gap of anatase TiO 2 (about 3.2 eV) only allows it to absorb UV light. TiO 2 nanoparticles modified by conditional conjugated polymers show excellent photocatalytic activity under visible light. However, these conjugated polymers are not only expensive, but also difficult to process. Polyvinyl chloride (PVC) was heat‐treated at high temperature to remove HCl and a C?C conjugated chain structure was obtained. When TiO 2 nanoparticles were dispersed into the conjugated polymer film derived from PVC, this composites film exhibited high visible light photocatalytic activity. RESULTS: The photocatalytic activity of TiO 2/heat‐treated PVC (HTPVC) film was investigated by degrading Rhodamine B (RhB) under visible light irradiation. The photodegradation of RhB follows apparent first‐order kinetics. The rate constants of RhB photodegradation in the presence of the TiO 2/HTPVC films with different mass content of TiO 2 are 16–56 and 4–14 times that obtained in the presence of the pure HTPVC and TiO 2/polymethyl methacrylate (PMMA) composite film, respectively. The TiO 2/HTPVC film showed excellent photocatalytic activity and stability after 10 cycles under visible light irradiation. CONCLUSION: TiO 2/HTPVC film exhibits high visible light photocatalytic activity and stability. Copyright © 2012 Society of Chemical Industry 相似文献
18.
Highly efficient Eu-TiO 2/graphene composites were synthesized by a two-step method such as sol-gel and hydrothermal process. The synthesized photocatalysts were characterized by XRD, TEM, XPS, UV–vis diffuse reflectance spectroscopy and photoluminescence (PL) spectroscopy. The results confirmed that anatase Eu-TiO 2 nanoparticles with average 10 nm sizes were successfully deposited on two-dimensional graphene sheets. The UV–visible spectroscopy showed a red shift in the absorption edge of TiO 2 due to Eu doping and graphene incorporation. Moreover, effective charge separation in Eu-TiO 2/graphene composites was confirmed by PL emission spectroscopy compared to TiO 2/graphene, Eu-TiO 2 and pure TiO 2. The photocatalytic activity for H 2 evolution over prepared composites was studied under visible light irradiation (λ ≥ 400 nm). The results demonstrate that photocatalytic performance of the photocatalysts for hydrogen production increases with increasing doping concentration of Eu upto 2 at%. However, further increase in doping content above this optimum level has decreased the performance of photocatalyst. The enhanced photocatalytic performance for H 2 evolution is attributed to extended visible light absorption, suppressed recombination of electron-hole pairs due to synergistic effects of Eu and graphene. 相似文献
19.
TiO 2 nanoparticles modified with 5-( p-hydroxylphenyl)-10,15,20-triphenylporphyrin (HTPP), 5-( p-hydroxylphenyl)-10,15,20-triphenylporphyrin zinc (ZnHTPP) and trans-dichloro-5-( p-hydroxylphenyl)-10,15,20-triphenylporphyrin tin (SnHTPP) were prepared in order to improve the visible photocatalytic activity of TiO 2 nanoparticles. The photocatalytic activity of the modified TiO 2 nanoparticles was investigated by carrying out the photodegradation of methyl orange in aqueous solution under visible light irradiation. The TiO 2 nanoparticles modified with SnHTPP show the highest visible photocatalytic activity with a degradation ratio of 86% of methyl orange after 180 min irradiation among three catalysts. This result indicates that the central metal ions in porphyrins can significantly influence the sensitization efficiency of porphyrins. In addition, the photoelectrochemical behavior of the modified TiO 2 nanoparticles was examined and related to their photocatalytic activity. Finally, the photocatalytic mechanism was discussed preliminarily. 相似文献
20.
TiO 2 thin films were fabricated through hydrothermal method. Silver nanoparticles were loaded on TiO 2 thin films via photoreduction technique. Subsequently, the graphene quantum dots (GQDs) were spin‐coated on the Ag/TiO 2 nanocomposites thin films. The crystal structure, surface morphology and UV‐vis absorbance were tested by XRD, SEM and ultraviolet‐visible spectrophotometer. These results indicated that Ag nanoparticles and GQDs are anchored on the TiO 2 nanorods. Absorbance of Ag/TiO 2 and GQDs/Ag/TiO 2 nanocomposite thin films have been extended into the visible region. Visible‐light response of the samples were investigated by electrochemical workstation. The photoresponse of the sample can be enhanced by sensitization of the Ag nanoparticles and GQDs. The enhanced visible‐light response may be due to the surface plasmon resonance of silver nanoparticles and visible absorbance of GQDs. The highest photocatalytic activity has been observed in the 9‐GQDs/Ag/TiO 2 composite thin film. The efficient charge separation and transportation can be achieved by introducing the Ag nanoparticles and GQDs in the TiO 2 thin film. 相似文献
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