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1.
A novel molybdenum disulfide (MoS 2) and graphitic carbon nitride (g-C 3N 4) composite photocatalyst was synthesized using a low temperature hydrothermal method. MoS 2 nanoparticles formed on g-C 3N 4 nanosheets greatly enhanced the photocatalytic activity of g-C 3N 4. The photocatalyst was tested for the degradation of methyl orange (MO) under simulated solar light. Composite 3.0 wt.% MoS 2/g-C 3N 4 showed the highest photocatalytic activity for MO decomposition. MoS 2 nanoparticles can increase the interfacial charge transfer and thus prevent the recombination of photo-generated electron–hole pairs. The novel MoS 2/g-C 3N 4 composite is therefore shown as a promising catalyst for photocatalytic degradation of organic pollutants using solar energy. 相似文献
2.
A series of g-C 3N 4–Sb 2S 3/Sb 4O 5Cl 2 (SCL-CX) composite photocatalysts were successfully prepared via a hydrothermal method. The as-prepared materials were characterized by TM3000, powder X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and UV–vis diffuse reflectance spectra (UV–vis DRS). The obtained photocatalyst showed higher photocatalytic activity than pure g-C 3N 4, Sb 4O 5Cl 2 and Sb 2S 3/Sb 4O 5Cl 2 (SCL). The optimum photocatalytic of the composite with the mass of 170 mg g-C 3N 4 and a degradation efficiency up to 95% for methyl orange (MO) under visible light was achieved within 60 min. The enhanced photocatalytic performance could be attributed to the stronger absorption in the visible region and the more efficient electron–hole separation. 相似文献
3.
The graphitic carbon nitride (g-C 3N 4) was rapidly synthesized via direct high-energy microwave heating approach. During the preparation process, only low-cost melamine and artificial graphite powders were used, without any metal catalysts or inert protective gas. The microstructure was investigated by using X-ray diffraction (XRD), Flourier transformed infrared (FT-IR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM). The spectra of XRD and HRTEM indicated that the obtained g-C 3N 4 had a high crystallinity. The optical spectra covering Photoluminescence (PL) and Ultraviolet-visible (UV–vis) were also measured at room temperature. PL peak and UV–vis absorption edge of the g-C 3N 4 were shown at 455 nm and 469 nm, respectively, indicating visible-light photocatalytic property. Finally, the photocatalytic activity of g-C 3N 4 was investigated and evaluated as photocatalyst for the photo-degradation of Rhodamine B (RhB) and Methyl Orange (MO) in aqueous solution under visible-light ( λ>420 nm) irradiation, respectively. Results indicated that the g-C 3N 4 sample displayed an excellent performance of removing of RhB and MO due to the improved crystallinity and large surface area of 126 m 2/g. After the visible-light photocatalytic reaction for 40 min, the decolorization ratios of RhB and MO reached up to 100% and 94.2%, respectively. 相似文献
4.
Developing photocatalysts with specific morphology and good photocatalytic activities promises good opportunities to discover the geometry-dependent properties. In the present work, ring-like anatase TiO 2 with dominant {001} facets exposed were successfully synthesized via a one-pot solvothermal process of tetrabutyl titanate and hydrofluoric acid solution at 180 °C for 8 h. We found that hydrofluoric acid plays an important role in the formation of ring-like TiO 2. The morphology and microstructure were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Brunauer–Emmett–Teller N 2 gas adsorption–desorption isotherms. The photocatalytic activity was evaluated by photocatalytic oxidation degradation of methylene blue aqueous solution under UV light. Results showed that ring-like TiO 2 with {001} facets exposed exhibited an excellent photocatalytic activities due to its unique structure: Nanosheets with hole. 相似文献
5.
Molybdenum doped graphitic carbon nitride (g-C 3N 4) catalysts were prepared by a simple pyrolysis method using melamine and ammonium molybdate as precursors. The characterization results indicated that the obtained Mo-doped g-C 3N 4 catalysts had worm-like mesostructures with higher surface area. Introduction of Mo species can effectively extend the spectral response property and reduce the recombination rate of photogenerated electrons and holes. CO 2 photocatalytic reduction tests showed that the Mo-doped g-C 3N 4 catalysts exhibited considerably higher activity (the highest CO and CH 4 yields of 887 and 123 μmol g − 1-cat., respectively, after 8 h of UV irradiation.) compared with pure g-C 3N 4 from melamine. 相似文献
6.
BiPO 4/g-C 3N 4 with different amounts of BiPO 4 was prepared through wet impregnation with calcination method. The BiPO 4/g-C 3N 4 showed large surface area (172.9 m 2 g − 1) and the incorporation of BiPO 4 caused a red-shift of g-C 3N 4 in visible light. The photocatalytic degradation of toluene over the samples was investigated. The degradation of toluene could get 82% in BiPO 4/g-C 3N 4 photocatalysts under optimum reaction conditions. The BiPO 4/g-C 3N 4 exhibited a higher photocatalytic activity than pure g-C 3N 4 or BiPO 4. The improved photoactivity of BiPO 4/g-C 3N 4 could be attributed to strong absorption in visible light and effective separation of photo-induced hole-electron pairs between BiPO 4 and g-C 3N 4. 相似文献
7.
Two kinds of TiO 2 with novel structures, interpenetrating anatase TiO 2 tablets (IP-TiO 2), and overlapping anatase TiO 2 nanosheets (OL-TiO 2) with exposed {0 0 1} facets, are synthesized. The graphene oxide (GO) supported ultrathin TiO 2 nanosheets (OL-TiO 2/GO) is also prepared by one-pot hydrothermal method. The microscopic feature, morphology, phase, and nitrogen adsorption–desorption isotherms are characterized. The performance of photocatalytic degradation of methyl blue is also measured. Compared with IP-TiO 2, the OL-TiO 2 with GO possess higher photocatalytic efficiency. The GO can improve the photocatalytic property by increasing specific surface area, accelerating the separation of electron–hole pairs, as well as extending the electron life. The growth process of TiO 2 nanosheets on graphene oxide layers probably follows a step-growth mechanism with F − as morphology controlling agent. The steps on the surface can improve the photocatalytic activity further due to the increase of dangling bonds of 5-coordinated Ti (Ti 5c) which are considered to be the active sites in the photocatalytic reaction. 相似文献
8.
The development of a graphitic carbon nitride (g-C 3N 4) photocatalyst is of great importance to a variety of visible utilization application fields. The desired high efficiency can be achieved by employing well-controlled g-C 3N 4 nanostructures. In this study, we successfully synthesized high surface area g-C 3N 4 nanowires and nanofibers using a cyanuric chloride and melamine precursor dispersed in a solvothermal reaction and with a subsequent calcination step. The obtained novel nanowire product had a diameter of 10–20 nm and a length of several hundreds of nanometers, while the nanofibers revealed fibrous nanostructures of randomly dispersed fibers with an average diameter of ~15 nm. The adsorption and photocatalytic experimental results indicated that the as-prepared nanowires and nanofibers showed enhanced activities compared with bulk g-C 3N 4. Based on our experimental results, a possible photocatalytic mechanism with hydroxyl and superoxide radical species as the main active species in photocatalysis was proposed. Moreover, our strategy may provide progress toward the design and practical application of 1D g-C 3N 4 nanostructures in the adsorption and photocatalytic degradation of pollutants. 相似文献
9.
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
10.
The nanocomposites of WO 3 nanoparticles and exfoliated graphitized C 3N 4 (g-C 3N 4) particles were prepared and their properties were studied. For this purpose, common methods used for characterization of solid samples were completed with dynamic light scattering (DLS) method and photocatalysis, which are suitable for study of aqueous dispersions.The WO 3 nanoparticles of monoclinic structures were prepared by a hydrothermal method from sodium tungstate and g-C 3N 4 particles were prepared by calcination of melamine forming bulk g-C 3N 4, which was further thermally exfoliated. Its specific surface area (SSA) was 115 m 2 g −1.The nanocomposites were prepared by mixing of WO 3 nanoparticles and g-C 3N 4 structures in aqueous dispersions acidified by hydrochloric acid at pH = 2 followed by their separation and calcination at 450 °C. The real content of WO 3 was determined at 19 wt%, 52 wt% and 63 wt%. It was found by the DLS analysis that the g-C 3N 4 particles were covered by the WO 3 nanoparticles or their agglomerates creating the nanocomposites that were stable in aqueous dispersions even under intensive ultrasonic field. Using transmission electron microscopy (TEM) the average size of the pure WO 3 nanoparticles and those in the nanocomposites was 73 nm and 72 nm, respectively.The formation of heterojunction between both components was investigated by UV–Vis diffuse reflectance (DRS) and photoluminescence (PL) spectroscopy, high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), photocatalysis and photocurrent measurements. The photocatalytic decomposition of phenol under the LED source of 416 nm identified the formation of Z-scheme heterojunction, which was confirmed by the photocurrents measurements. The photocatalytic activity of the nanocomposites decreased with the increasing content of WO 3, which was explained by shielding of the g-C 3N 4 surface by bigger WO 3 agglomerates. This study also demonstrates a unique combination of various characterization techniques working in solid and liquid phase. 相似文献
11.
In this work, ultrathin graphene-like carbon nitride nanosheets with rich nanoporous and excellent hydrophilic characteristics were synthesized by a simple and effective thermal exfoliation of bulk g-C 3N 4. In order to fully understand the effect of thermal exfoliation conditions on the texture, surface state, and photocatalytic activity of the resulting g-C 3N 4, a series of exfoliated g-C 3N 4 were prepared by adjusting the thermal exfoliation temperature and time. The detailed characterization and analysis distinctly suggested that increasing exfoliation temperature led to a large number of nitrogen vacancies and increased specific surface area, further prolonging exfoliation time, the thermal exfoliation degree was enhanced, more carbon vacancies and enlarged pore volume formed in the resulting products. Further, the exfoliation degree and photocatalytic ability of the resultant products were enhanced by increasing thermal exfoliation temperature and time. The optimized ultrathin graphene-like carbon nitride nanosheets exhibited a 89.6% degradation efficiency for Rh6G only in 10 min, which was much faster than other such nanosheets reported in previous literature. 相似文献
12.
Graphitic carbon nitride (g-C3N4) has received much interest as a visible-light-driven photocatalyst for degrading pollutants such as organic dyes and antibiotics. However, g-C3N4 bulk activity could not meet expectations due to its rapid recombination of photogenerated electron–hole pairs and low specific surface area. In our study, melamine was thermally treated one-step in the presence of NH4Cl to produce g-C3N4 nanosheets. The characterizations of surface morphology and optical properties of all g-C3N4 samples were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectrum (XPS), transmission electron microscopy (TEM), and UV–visible diffuse reflectance spectroscopy. Compared to bulk g-C3N4, g-C3N4 nanosheets demonstrated excellent photocatalytic activities, with approximately 98% RhB removal after 210 min of visible light irradiation. Furthermore, the effect of catalyst dosage, pH, and RhB concentration on the removal percentage dye of g-C3N4 nanosheets was also investigated. h+ and ?O2? species were demonstrated as the key reactive species for the RhB. Besides, ECN exposed a tetracycline degradation efficiency of 80.5% under visible-light irradiation for 210 min, which is higher than BCN (60.8%). The improved photocatalytic activity of g-C3N4 nanosheets is due to the restriction of the recombination of photogenerated electrons/hole pairs, as provided by photoluminescence spectra and Nyquist plot. As a result, our research may offer an effective approach to fabricating g-C3N4 nanosheets with high photocatalytic activity and high stability for environmental decontamination. 相似文献
13.
g-C 3N 4 as a new metal-free photocatalytic material for water splitting has attracted much attention in recent years, but its photocatalytic efficiency needs further improvement. Here we synthesized novel C 60/graphene/g-C 3N 4 composite photocatalytic materials with high hydrogen generation ability for water splitting under visible light radiation (λ>420 nm). These materials take full advantage of the electron conduction expressing of graphene and the superior-strong electron-attracting ability of C 60. The mutually-reinforcing synergy between graphene and C 60 improves the migration and utilization efficiency of photo-generated electrons and accelerates the separation of photo-generated charges, thus significantly enhancing the hydrogen generation capacity of g-C 3N 4. The hydrogen production amount and rate of C 60/graphene/g -C 3N 4 (10 mg/L C 60 and graphene) after 10 h are 5449.5 µmol/g and 545 µmol/g/h, which is 539.6 times of pure g-C 3N 4 under the same condition. The values are 50.8 and 4.24 times of graphene/g-C 3N 4 (10 mg/L graphene) and C 60/g-C 3N 4 (10 mg/L C 60), respectively. The apparent quantum yield of C 60/graphene/g -C 3N 4 (10 mg/L C 60 and graphene) in 97 h is about 7.2%. The improvement of hydrogen generation activity in 97 h suggests the high long-time stability of C 60/graphene/g -C 3N 4 in photocatalytic water spitting. The photocatalytic ability of C 60/graphene/g -C 3N 4 can be controlled by regulating the addition of graphene and C 60. The mutually-reinforcing synergy between graphene and C 60 was proved by X-ray photoelectron spectroscopy, photoluminescence spectrum and organic electron acceptors of MV 2+. Thus, the joint action of C 60 and graphene promotes the migration, separation and utilization of photo-generated electrons, which is responsible for the significant enhancement of photocatalytic performance. 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.
The solar light sensitive g-C 3N 4/TiO 2 heterojunction photocatalysts containing 20, 50, 80, and 90 wt% graphitic carbon nitride (g-C 3N 4) were prepared by growing Titania (TiO 2) nanoparticles on the surfaces of g-C 3N 4 particles via one step hydrothermal process. The hydrothermal reactions were allowed to take place at 110 °C at autogenous pressure for 1 h. Raman spectroscopy analyses confirmed that an interface developed between the surfaces of TiO 2 and g-C 3N 4 nanoparticles. The photocatalyst containing 80 wt% g-C 3N 4 was subsequently heat treated 1 h at temperatures between 350 and 500 °C to improve the photocatalytic efficiency. Structural and optical properties of the prepared g-C 3N 4/TiO 2 heterojunction nanocomposites were compared with those of the pristine TiO 2 and pristine g-C 3N 4 powders. Photocatalytic activity of all the nanocomposites and the pristine TiO 2 and g-C 3N 4 powders were assessed by the Methylene Blue (MB) degradation test under solar light illumination. g-C 3N 4/TiO 2 heterojunction photocatalysts exhibited better photocatalytic activity for the degradation of MB than both pristine TiO 2 and g-C 3N 4. The photocatalytic efficiency of the g-C 3N 4/TiO 2 heterojunction photocatalyst heat treated at 400 °C for 1 h is 1.45 times better than that of the pristine TiO 2 powder, 2.20 times better than that of the pristine g-C 3N 4 powder, and 1.24 times better than that of the commercially available TiO 2 powder (Degussa P25). The improvement in photocatalytic efficiency was related to i) the generation of reactive oxidation species induced by photogenerated electrons, ii) the reduced recombination rate for electron-hole pairs, and iii) large specific surface area. 相似文献
16.
Surface-enhanced Raman scattering (SERS) substrates with high SERS activity and stability are important for SERS sensors. A facile method was developed to fabricate efficient and stable SERS substrates by combining Ag nanoparticles (NPs) and micro-scale sheeted graphitic carbon nitride (g-C 3N 4). The g-C 3N 4/Ag NPs hybrid could provide a great number of hot spots and concentrated the analyte by the π–π stacking interaction between analyte molecules and g-C 3N 4, making a dramatic Raman enhancement. Moreover, the g-C 3N 4/Ag NPs hybrid uniformly immobilized Ag NPs on the surface and edges of g-C 3N 4 sheets by an interaction between Ag NPs and g-C 3N 4, leading to much improved long-term stability. This could be explained in terms of the electron–donor effect of g-C 3N 4, which was further confirmed by density functional theory calculations. The inherent Raman enhancing effect of g-C 3N 4 itself also contributed to the total SERS responses. Due to multiple enhancement contributions, the g-C 3N 4/Ag NPs hybrid exhibited a strong Raman enhancement effect for with an enhancement factor of 4.6 × 10 8 (evaluated by using crystal violet as a probe), and possessed wide adaptability from dyes, pesticides to bio-molecules. 相似文献
17.
A novel TiO 2 − xN x/BN composite photocatalyst was prepared via a facile method using melamine–boron acid adducts (M·2B) and tetrabutyl titanate as reactants. The morphological results confirmed that nitrogen-doped TiO 2 nanoparticles were uniformly coated on the surface of porous BN fibers. A red shift of absorption edge from 400 nm (pure TiO 2) to 520 nm (TiO 2 − xN x/BN composites) was observed in their UV–Vis light absorption spectra. The TiO 2 − xN x/BN photocatalysts exhibited enhanced photocatalytic activity for the degradation of Rhodamine B (RhB) and the highest photocatalytic degradation efficiency reached 97.8% under visible light irradiation for 40 min. The mechanism of enhanced photocatalytic activity was finally proposed. 相似文献
18.
Monodispersed flower-like titanate superstructure was successfully prepared by simple hydrothermal process without any surfactant or template. N 2-sorption analysis, scanning electron microscopy (SEM), and X-ray diffraction (XRD) observation of as-synthesized product revealed the formation of flower-like titanate with diameter of about 250–450 nm and BET surface area ( SBET) of 350.7 m 2 g ?1. Upon thermal treatment at 500 °C, the titanate nanosheets were converted into anatase TiO 2 with moderate deformation of their structures. The as-prepared flower-like titanate showed high photocatalytic activity for H 2 evolution from water splitting reaction. Moreover, the sample heat treated at 500 °C exhibited higher photocatalytic activity than that of commercial TiO 2 anatase powder (ST-01). 相似文献
19.
Novel photocatalysts based on silver (Ag), TiO 2, and graphene were successfully synthesized by microwave-assisted hydrothermal method. The prepared photocatalysts were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) specific surface area analysis, X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). The influence of silver loading and graphene incorporation on photocatalytic hydrogen (H 2) production of as-prepared samples was investigated in methanolic aqueous solution under visible light irradiation (λ≥420 nm). The results showed that Ag–TiO 2/graphene composite had appreciably enhanced photocatalytic H 2 production performance under visible light illumination compared to pure TiO 2, Ag–TiO 2 and TiO 2/graphene samples. The enhanced photocatalytic hydrogen production activity of Ag–TiO 2/graphene composite under visible light irradiation could be attributed to increased visible light absorption, reduced recombination of photogenerated charge carriers and high specific surface area. This novel study provides more insight for the development of novel visible light responsive TiO 2− graphene based photocatalysts for energy applications. 相似文献
20.
TiO 2 hollow nanostructures were successfully synthesized by a controlled hydrothermal precipitation reaction using Resorcinol–Formaldehyde resin spheres as templates in aqueous solution, and then removal of the RF resins spheres by calcination in air at 450 °C for 4 h. The obtained TiO 2 hollow spheres were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N 2 adsorption–desorption analysis, and UV–visible diffuse reflectance spectroscopy. The photocatalytic activity of the as-prepared samples was evaluated by photocatalytic decolorization of rhodamine B aqueous solution at ambient temperature under UV illumination. The results indicated TiO 2 hollow nanostructures exhibit the excellent photocatalytic activity probably due to the unique hollow micro-architectures. 相似文献
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