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1.
Highly efficient visible-light-driven heterojunction photocatalysts, spindle-shaped nanoporous TiO 2 coupled with graphitic g-C 3N 4 nanosheets have been synthesized by a facile one-step solvothermal method. The as-prepared photocatalysts were characterized by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N 2 adsorption-desorption analysis and UV–vis diffuse reflectance spectrometry (DRS), proving a successful modification of TiO 2 with g-C 3N 4. The results showed spindle-shaped nanoporous TiO 2 microspheres with a uniform diameter of about 200 nm dispersed uniformly on the surface of graphitic g-C 3N 4 nanosheets. The g-C 3N 4/TiO 2 hybrid materials exhibited higher photocatalytic activity than either pure g-C 3N 4 or nanoporous TiO 2 towards degradation of typical rhodamine B (RhB), methyl blue (MB) and methyl orange (MO) dyes under visible light (>420 nm), which can be largely ascribed to the increased light absorption, larger BET surface area and higher efficient separation of photogenerated electron–hole pairs due to the formation of heterostructure. In addition, the possible transferred and separated behavior of electron–hole pairs and photocatalytic mechanisms on basis of the experimental results are also proposed in detail. 相似文献
2.
Graphitic carbon nitride (g-C 3N 4) has attracted increasing interest as a visible-light-active photocatalyst. In this study, saddle-curl-edge-like g-C 3N 4 nanosheets were prepared using a pellet presser (referred to as g-CN P nanosheets). Urea was used as the precursor for the preparation of g-C 3N 4. Thermal polymerization of urea in a pellet form significantly affected the properties of g-C 3N 4. Systematic investigations were performed, and the results for the modified g-C 3N 4 nanosheets are presented herein. These results were compared with those for pristine g-C 3N 4 to identify the factors that affected the fundamental properties. X-ray diffraction analysis and high-resolution transmission electron microscopy revealed a crystallinity improvement in the g-CN P nanosheets. Fourier-transform infrared spectroscopy provided clear information regarding the fundamental modes of g-C 3N 4, and X-ray photoelectron spectroscopy (XPS) peak-fitting investigations revealed the variations of C and N in detail. The light-harvesting property and separation efficiency of the photogenerated charge carriers were examined via optical absorption and photoluminescence studies. The valence band edge and conduction band edge potentials were calculated using XPS, and the results indicated a significant reduction in the bandgap for the g-CN P nanosheets. The Brunauer–Emmett–Teller surface area increased for the g-CN P nanosheets. The photocatalytic degradation performance of the g-CN P nanosheets was tested by applying a potential and using the classical dye Rhodamine B (RhB). The RhB dye solution was almost completely degraded within 28 min. The rate constant of the g-CN P nanosheets was increased by a factor of 3.8 compared with the pristine g-C 3N 4 nanosheets. The high crystallinity, enhanced light absorption, reduced bandgap, and increased surface area of the saddle-curl-edge-like morphology boosted the photocatalytic performance of the g-CN P nanosheets. 相似文献
3.
In this work, cobalt phosphide (CoP) nanoparticles were successfully decorated on an ultrathin g-C 3N 4 nanosheet photocatalysts by in situ chemical deposition. The built-in electric field formed by heterojunction interface of the CoP/g-C 3N 4 composite semiconductor can accelerate the transmission and separation of photogenerated charge-hole pairs and effectively improve the photocatalytic performance. TEM, HRTEM, XPS, and SPV analysis showed that CoP/g-C 3N 4 formed a stable heterogeneous interface and effectively enhanced photogenerated electron-hole separation. UV-vis DRS analysis showed that the composite had enhanced visible light absorption than pure g-C 3N 4 and was a visible light driven photocatalyst. In this process, NaH 2PO 2 and CoCl 2 are used as the source of P and Co, and typical preparation of CoP can be completed within 3 hours. Under visible light irradiation, the optimal H 2 evolution rate of 3.0 mol% CoP/g-C 3N 4 is about 15.1 μmol h −1. The photocatalytic activity and stability of the CoP/g-C 3N 4 materials were evaluated by photocatalytic decomposition of water. The intrinsic relationship between the microstructure of the composite catalyst and the photocatalytic performance was analyzed to reveal the photocatalytic reaction mechanism. 相似文献
4.
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
5.
The reasonable modulation of tri- s-triazine structure units of g-C 3N 4 is an effective method to optimize its intrinsic electronic and optical properties, thus boosting its photocatalytic hydrogen-evolution activity. Herein, amino groups are successfully introduced into the tri- s-triazine structure units of g-C 3N 4 nanosheets to improve their H 2-evolution activity via a facile oxalic acid-induced supramolecular assembly strategy. In this case, the resulting amino group-rich porous g-C 3N 4 nanosheets display a loose and fluffy structure with a large specific surface area (70.41 m 2 g ?1) and pore volume (0.50 cm 3? g ??1), and enhanced visible-light absorption (450–800 nm). Photocatalytic tests reveal that the amino group-rich porous g-C 3N 4 nanosheets (AP-CN1.0 nanosheets) exhibit a significantly elevated photocatalytic H 2-production activity (130.7 μmol h ?1, AQE = 5.58%), which is much greater than that of bulk g-C 3N 4 by a factor of 4.9 times. The enhanced hydrogen-generation performance of amino group-rich porous g-C 3N 4 nanosheets can be mainly attributed to the introduction of more amino groups, which can reinforce the visible-light absorption and work as the interfacial hydrogen-generation active centers to boost the photocatalytic hydrogen production. The present facile and effective regulation of tri- s-triazine structure units may provide an ideal route for the exploitation of novel and highly efficient g-C 3N 4 photocatalysts. 相似文献
6.
In order to overcome the problem of low photocatalytic rate of g-C 3N 4, the 3D Fe xS 1-x/g-C 3N 4 heterojunction was prepared via a simple one-pot solid method. The X-Ray Diffraction (XRD) and scanning electron microscope (SEM) results demonstrated that the Fe xS 1-x/g-C 3N 4 heterojunction was established and a g-C 3N 4 nanosheet was tightly bound to Fe xS 1-x. Compared with g-C 3N 4 samples, Fe xS 1-x coupling resulted in substantial enhancement of visible light absorption, moreover, the bandwidth of heterojunction was also expanded. In addition to effectively degrading RhB and reducing Cr(VI), the redox performance of Fe xS 1-x/g-C 3N 4 was also increased in the Cr(VI)/RhB mixed system. Based on a variety of experimental results, the enhanced synergistic photocatalytic activity of the 3D Fe xS 1-x/g-C 3N 4 heterojunction was attributed to enhancement of the separation of e - and h + in FeS 2, which resulted from the effective conversion of FeS into FeS 2 under UV-light irradiation. The type II heterojunction structure that was produced via one-pot solid fabrication also inhibited the recombination of electron/hole pairs. Fe xS 1-x doping and heterojunction building improve the photocatalysis capacity of g-C 3N 4 and broaden the visible-light response of pure g-C 3N 4. 相似文献
7.
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
8.
A series of onion-like carbon modified porous g-C 3N 4 (OLC/pg-C 3N 4) composites have been fabricated by a simple ultrasonic adsorption approach. The resultant OLC/pg-C 3N 4 composites exhibit excellent photocatalytic activity and stability towards the degradation of the dyes and phenol in aqueous solution under visible-light irradiation. The composite with 2.0 wt% OLC content shows the optimal photocatalytic activity for degrading rhodamine B (RhB), its rate constant is about three times that of pure pg-C 3N 4. The improved photocatalytic activity is mainly attributed to the synergetic effect of pg-C 3N 4 and OLC, including larger surface area, stronger visible light adsorption and efficient separation of photogenerated electrons and holes. Moreover, a possible mechanism of photocatalytic reaction over OLC/pg-C 3N 4 composite is proposed. 相似文献
9.
It is very essential to grow efficient and abundant photocatalysts for overall water cracking to produce hydrogen. Ni 3FeN nanosheets were synthesized by combining simple sol–gel and calcining methods using urea as nitrogen source. A heterostructure was constructed between Ni 3FeN and g-C 3N 4 to enhance the absorption capacity of visible light. The reformed Z-scheme Ni 3FeN/g-C 3N 4 heterojunction exhibited an excellent visible-light photocatalytic activity. The average hydrogen evolution rate of 5 wt% Ni 3FeN/g-C 3N 4 composite is 528.7 μmol h −1 g −1 due to the Z-scheme Ni 3FeN/g-C 3N 4 junction, which promotes the separation of photogenerated e −/h +. Interestingly, the average H 2 production of Ni 3FeN/g-C 3N 4 is nearly 8.3 and 3.6 times higher than that of Fe 4N/g-C 3N 4 and Ni 4N/g-C 3N 4, respectively, indicating that bimetallic nitrides as cocatalysts are more conducive to enhancing the performance of photocatalysts. Importantly, the Ni 3FeN/g-C 3N 4 composite exhibited good cycle stability, and the hydrogen production performance hardly changed after four cycle experiments. Furthermore, photoluminescence, electrochemical impedance spectroscopy, and transient photocurrent response show that Ni 3FeN/g-C 3N 4 heterojunction improves the separation efficiency of photoinduced e −/h +. This work provides a feasibility of the cocatalyst Ni 3FeN for use in photocatalytic hydrogen production. 相似文献
10.
Ag/g-C 3N 4 photocatalysts were synthesized by a rapid microwave-assisted polyol process. The characterization results showed monodisperse Ag nanoparticles with diameters of a few nanometers closely attached to the edges of g-C 3N 4. The presence of Ag nanoparticles in Ag/g-C 3N 4 photocatalysts enhanced the visible-light absorption and suppressed the recombination of photogenerated electron/hole pairs. The Ag/g-C 3N 4 photocatalysts exhibited the superior visible-light responsive photocatalytic activity for rhodamine B degradation. The mechanism of visible-light induced photocatalysis over Ag/g-C 3N 4 photocatalysts was also discussed. 相似文献
11.
Researchers have attempted to developing high-efficiency catalysts for photocatalytic hydrogen evolution and organic pollution elimination simultaneously to alleviate the issues of energy shortage and water pollution. In this work, we fabricated 3D interconnected porous boron doped polymeric g-C 3N 4 catalysts with efficient photocatalytic activity for hydrogen evolution and dye contaminant elimination under visible-light irradiation. The as-fabricated catalysts exhibited significantly enhanced hydrogen evolution (4.37 mmol g ?1 h ?1) and RhB contaminant elimination (96.37%) activity. Based on characterization and photocatalytic tests, an enhanced mechanism of the superior photocatalytic performance was proposed: 3D interconnected porous structure and B-doping have a synergistic effect on the greatly improved photocatalytic activity. The 3D interconnected structures endowed g-C 3N 4 with a higher specific surface area and abundant active sites and improved the capacity of rapid absorption to facilitate the photocatalytic process. B doping provided enhanced visible-light absorption capacity and a narrowed bandgap and served as a “highway” for electron-hole pairs to facilitate migration and separation and suppress the combination of photogenerated carriers. Besides, the possible mechanism of enhanced photocatalytic performance was elucidated according to the results of characterization measurements and active species analysis. 相似文献
12.
In this contribution, a Z-scheme mesoporous BiVO 4/g-C 3N 4 nanocomposite heterojunction with a considerable surface area and high crystallinity was synthesized by a simple soft and hard template-assisted approach. This material demonstrates superior visible light-driven photocatalysis for the photoreduction of Hg(II) ions. TEM and XRD results show that the mesoporous BiVO 4 NPs, with a monoclinic phase and an ellipsoid-like shape, are highly dispersed onto the porous 2D surfaces of g-C 3N 4 nanosheets with a particle size of 5–10 nm. The obtained BiVO 4/g-C 3N 4 nanocomposites with a p-n heterojunction show significantly enhanced Hg(II) photoreduction efficiency compared to the mesoporous BiVO 4 NPs and pristine g-C 3N 4. Among all synthesized photocatalysts, the 1.2% BiVO 4/g-C 3N 4 nanocomposite indicated the highest photoreduction of Hg(II) performance, reaching ~ 100% within 60 min; this result is 3.9 and 4.5 –fold larger than that of the BiVO 4 NPs and pristine g-C 3N 4. The Hg(II) photoreduction rates highly increase to 208.90, 314.95, 411.23 and 418.68 μmol g −1min −1 for the mesoporous 0.4, 0.8, 1.2 and 1.6% BiVO 4/g-C 3N 4 nanocomposites, respectively. The reduction rate of the mesoporous 1.2% BiVO 4/g-C 3N 4 nanocomposite demonstrated a 5.2 and 3.8 times larger increase than that of the pristine g-C 3N 4 nanosheets and pure BiVO 4 NPs. The superior Hg(II) photoreduction efficiency was ascribed to decreased carrier recombination and the improved utilization of visible light by constructing BiVO 4/g-C 3N 4 nanocomposites with a p-n junction. Transient photocurrent measurement and photoluminescence spectra were employed to confirm the possible Hg(II) photoreduction mechanism over these BiVO 4/g-C 3N 4 photocatalysts. This research provides an accessible route for the nanoengineered design of mesoporous BiVO 4/g-C 3N 4 heterostructures that demonstrated unique photocatalytic performance. 相似文献
13.
Photocatalytic degradation is an ecologically benign method of reducing organic contaminants in wastewater. To remove the pollutant 1-naphthol, highly efficient 0D/2D Bi 2MoO 6/g-C 3N 4 heterojunctions were successfully assembled by a one-step hydrothermal method, where zero-dimension (0D) Bi 2MoO 6 nanoparticles were firmly bonded to two-dimension (2D) g-C 3N 4 nanosheets. 0D/2D Bi 2MoO 6/g-C 3N 4 exhibited exceptional degradation efficiency for 1-naphthol with a removal rate of 81.5% after 60 min of visible light irradiation. The enhanced photocatalytic ability was attributed to the matched band structures and tightly connected heterojunctions, which effectively prevented the recombination of photogenerated carriers. Besides, the photodegradation mechanism was revealed by investigating the catalysts' crystal phase, morphology, physicochemical and optical properties. This work introduces a novel method for one-step preparation of 0D/2D photocatalysts and advances the utilization of photodegradation for organic pollutants. 相似文献
14.
Yttrium-doped graphitic carbon nitride (Y/g-C 3N 4) catalysts were prepared via a facile pyrolysis method with urea used as a precursor and yttrium nitrate as the Y source. Characterization results show that an appropriate doping ratio of Y can be embedded into in-planes of g-C 3N 4. The Y/g-C 3N 4 catalysts are characterized by hierarchical porosity, large specific surface area, and large pore volume. Introduction of Y species effectively extends the spectral response of g-C 3N 4 from ultraviolet to visible region and decelerates the recombination of photogenerated electrons and holes. Because of these properties, the Y/g-C 3N 4 catalysts show an enhanced photocatalytic performance in rhodamine B degradation under visible light. 相似文献
15.
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
16.
A series of assembled porous TiO 2/g-C 3N 4 (TC) powders composed of spherical nanoparticles were synthesized by controlling the molar ratio of urea to tetrabutyl titanate (TBOT) in a facile hydrothermal process. A nanosheets-constructed hierarchical structure was obtained at the molar ratio of urea to TBOT of 10:1, which possessed uniform mesopores with bimodal distribution (0.5–1.5 nm and 2–20 nm) and interconnected macropores between TC nanosheets. The specific surface area achieved 98.4 m 2 g ?1. X-ray diffraction (XRD) patterns and high resolution transmission electron microscope (HRTEM) analysis proved that the nanosheets are made of overlapping TC nanocomposite. Photoluminescence (PL) spectra results illustrated that a well-defined hierarchical porous structure is particularly desired for the low recombination rate of carriers. Further, the TC-decorated carbon fiber (CF) cloth was obtained based on the nanosheets assembled hierarchical structure, which showed more outstanding photocatalytic behavior with high degradation capability for Rhodamine B (RhB) (99.9%) and tetracycline hydrochloride (89.8%) at 60 min by 500 W Xe lamp irradiation. After five consecutive cycles, the degradation efficiencies of TC/CF cloth for both RhB and tetracycline hydrochloride all remained above 90% of the initial value. 相似文献
17.
In this paper, WO 3 nanorods (NRs)/g-C 3N 4 composite photocatalysts were constructed by assembling WO 3 NRs with sheet-like g-C 3N 4. The as-synthesized photocatalysts were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, UV–vis diffuse reflectance spectroscopy and photoluminescence. The photocatalytic activity of the photocatalysts was evaluated by degradation of Rhodamine B (RhB) under simulated sunlight irradiation. Compared to pristine WO 3 NRs and g-C 3N 4, WO 3 NRs/g-C 3N 4 composites exhibit greatly enhanced photocatalytic activities. The enhanced performance of WO 3 NRs/g-C 3N 4 composite photocatalysts was mainly ascribed to the synergistic effect between WO 3 NRs and g-C 3N 4, which improved the photogenerated carrier separation. A possible degradation mechanism of RhB over the WO 3 NRs/g-C 3N 4 composite photocatalysts was proposed. 相似文献
18.
g-C 3N 4 has received extensive attention because of its good chemical stability and environmental friendliness. Since g-C 3N 4 prepared from various precursors had different photocatalytic activities, g-C 3N 4 materials marked as U-gCN, D-gCN and M-gCN were synthesized from various precursors of urea, dicyandiamide and melamine, respectively. The D-gCN and M-gCN with smaller surface area were heated again to obtain exfoliated g-C 3N 4 with 2D nanosheet morphology and larger specific surface area named D-gCN-L and M-gCN-L, respectively. The synthesized bulk g-C 3N 4 and g-C 3N 4 2D nanosheets were characterized by XRD, SEM, BET, PL, UV–Vis diffuse reflectance spectroscopy, XPS, zeta potential and TG. The photocatalytic degradation of methylene blue (MB) was carried out on U-gCN, D-gCN, M-gCN, D-gCN-L and M-gCN-L, and D-gCN-L shows the highest photocatalytic degradation performance because of its larger specific surface area, lower electron-hole recombination and wide light absorption range. 相似文献
19.
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
20.
The g-C3N4 nanosheet was prepared by calcination method, the MoS2 nanosheet was prepared by hydrothermal method. The g-C3N4/MoS2 composites were prepared by ultrasonic composite in anhydrous ethanol. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet–visible spectroscopy, and photoluminescence techniques were used to characterize the materials. The photocatalytic degradation of Rhodamine B (Rh B) by g-C3N4/MoS2 composites with different mass ratios was investigated under visible light. The results show that a small amount of MoS2 combined with g-C3N4 can significantly improve photocatalytic activity. The g-C3N4/MoS2 composite with a mass ratio of 1:8 has the highest photocatalytic activity, and the degradation rate of Rh B increases from 50 to 99.6%. The main reason is that MoS2 and g-C3N4 have a matching band structure. The separation rate of photogenerated electron–hole pairs is enhanced. So the g-C3N4/MoS2 composite can improve the photocatalytic activity. Through the active material capture experiment, it is found that the main active material in the photocatalytic reaction process is holes, followed by superoxide radicals. 相似文献
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