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1.
《Ceramics International》2016,42(16):18443-18452
Highly efficient visible-light-driven heterojunction photocatalysts, spindle-shaped nanoporous TiO2 coupled with graphitic g-C3N4 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), N2 adsorption-desorption analysis and UV–vis diffuse reflectance spectrometry (DRS), proving a successful modification of TiO2 with g-C3N4. The results showed spindle-shaped nanoporous TiO2 microspheres with a uniform diameter of about 200 nm dispersed uniformly on the surface of graphitic g-C3N4 nanosheets. The g-C3N4/TiO2 hybrid materials exhibited higher photocatalytic activity than either pure g-C3N4 or nanoporous TiO2 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.
《Ceramics International》2015,41(4):5600-5606
In this paper, WO3 nanorods (NRs)/g-C3N4 composite photocatalysts were constructed by assembling WO3 NRs with sheet-like g-C3N4. 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 WO3 NRs and g-C3N4, WO3 NRs/g-C3N4 composites exhibit greatly enhanced photocatalytic activities. The enhanced performance of WO3 NRs/g-C3N4 composite photocatalysts was mainly ascribed to the synergistic effect between WO3 NRs and g-C3N4, which improved the photogenerated carrier separation. A possible degradation mechanism of RhB over the WO3 NRs/g-C3N4 composite photocatalysts was proposed.  相似文献   

3.
《Ceramics International》2020,46(6):7888-7895
Graphite carbon nitride (g-C3N4) is an appealing metal-free photocatalyst for hydrogen evolution, but the potential has been limited by its poor visible-light absorption and unsatisfactory separation of photo-induced carriers. Herein, a facile one-pot strategy to fabricate carbon self-doped g-C3N4 composite through the calcination of dicyanamide and trace amounts of dimethylformamide is presented. The as-obtained carbon self-doped catalyst is investigated by X-ray photoelectron spectroscopy (XPS), confirming the substitution of carbon atoms in original sites of bridging nitrogen. We demonstrate that the as-prepared materials display remarkably improved visible-light absorption and optimized electronic structure under the premise of principally maintaining the tri-s-triazine based crystal framework and surface properties. Furthermore, the carbon doped g-C3N4 composite simultaneously weakens the transportation barrier of charge carriers, suppresses charge recombination and raises the separated efficiency of photoinduced holes and electrons on account of the extension of pi conjugated system. As a result, carbon self-doped g-C3N4 exhibits 4.3 times greater photocurrent density and 5.2 times higher hydrogen evolution rate compared with its bulk counterpart under visible light irradiation.  相似文献   

4.
The reasonable modulation of tri-s-triazine structure units of g-C3N4 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-C3N4 nanosheets to improve their H2-evolution activity via a facile oxalic acid-induced supramolecular assembly strategy. In this case, the resulting amino group-rich porous g-C3N4 nanosheets display a loose and fluffy structure with a large specific surface area (70.41 m2 g?1) and pore volume (0.50 cm3? g??1), and enhanced visible-light absorption (450–800 nm). Photocatalytic tests reveal that the amino group-rich porous g-C3N4 nanosheets (AP-CN1.0 nanosheets) exhibit a significantly elevated photocatalytic H2-production activity (130.7 μmol h?1, AQE = 5.58%), which is much greater than that of bulk g-C3N4 by a factor of 4.9 times. The enhanced hydrogen-generation performance of amino group-rich porous g-C3N4 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-C3N4 photocatalysts.  相似文献   

5.
Ag/g-C3N4 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-C3N4. The presence of Ag nanoparticles in Ag/g-C3N4 photocatalysts enhanced the visible-light absorption and suppressed the recombination of photogenerated electron/hole pairs. The Ag/g-C3N4 photocatalysts exhibited the superior visible-light responsive photocatalytic activity for rhodamine B degradation. The mechanism of visible-light induced photocatalysis over Ag/g-C3N4 photocatalysts was also discussed.  相似文献   

6.
A series of assembled porous TiO2/g-C3N4 (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 m2 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   

7.
《Ceramics International》2017,43(3):3314-3318
A series of NiTiO3/Ag3PO4 composites were prepared by a simple ion-exchange deposition method. The composition and morphology of the samples were determined by XRD, EDS and SEM. UV–vis DRS was used to characterize their optical absorption properties. The loading of NiTiO3 could promote the efficient separation of photoinduced electron-hole pairs and enhance the charge carrier transport to improve the photocatalytic activity. The APO-5 composite exhibited the best photocatalytic activity for the degradation of methyl violet (MV). Kinetics studies indicated that the APO-5 composite showed an apparent rate constant of 0.115 min−1, which was 2.61 times that of pure Ag3PO4.  相似文献   

8.
《Ceramics International》2016,42(3):4063-4071
The graphitic carbon nitride (g-C3N4) 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-C3N4 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-C3N4 were shown at 455 nm and 469 nm, respectively, indicating visible-light photocatalytic property. Finally, the photocatalytic activity of g-C3N4 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-C3N4 sample displayed an excellent performance of removing of RhB and MO due to the improved crystallinity and large surface area of 126 m2/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   

9.
Photocatalytic water splitting for hydrogen production (H2) is one of the main potential applications of photocatalytic technology, which can use solar energy as the energy required for chemical reactions to alleviate the energy crisis. In this work, zero-dimensional/two-dimensional (0D/2D) contact surface CdS/α-Fe2O3 (CF) heterojunction photocatalyst was synthesized via a simple solvothermal method. Photocatalytic hydrogen production experiments revealed that the CF-15 sample shows the optimal photocatalytic H2 rate (1806 (μmol·h-1·g-1)) and apparent quantum efficiency (AQE = 13.7% at λ = 420 nm). The enhancement of photocatalytic performance is mainly attributed to the contact of 0D/2D interface and the synergistic effect of Z-scheme electron transfer mechanism. This work provides an effective way for modified composite semiconductor photocatalyst by constructing special interface heterojunction to achieve highly efficiently catalysis.  相似文献   

10.
Self-assembled 3D flower-like ZnO microstructures composed of nanosheets have been prepared on a large scale through a sol−gel-assisted hydrothermal method using Zn(NO3)2·6H2O, citric acid, and NaOH as raw materials. The product has been characterized by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The optical properties of the product have been examined by room temperature photoluminescence (PL) measurements. A possible growth mechanism of the 3D flower-like ZnO is proposed based on the results of experiments carried out for different hydrothermal treatment times. Experiments at different hydrothermal treatment temperatures have also been carried out to investigate their effect on the final morphology of the ZnO. The photocatalytic activities of the as-prepared ZnO have been evaluated by photodegradation of Reactive Blue 14 (KGL) under ultraviolet (UV) irradiation. The experimental results demonstrated that self-assembled 3D flower-like ZnO composed of nanosheets could be obtained over a relatively broad temperature range (90−150 °C) after 17 h of hydrothermal treatment. All of the products showed good photocatalytic performance, with the degree of degradation of KGL exceeding 82% after 120 min. In particular, the sample prepared at 120 °C for 17 h exhibited superior photocatalytic activity to other ZnO samples and commercial ZnO, and it almost completely degraded a KGL solution within 40 min. The relationship between photocatalytic activity and the structure, surface defects, and surface areas of the samples is also discussed.  相似文献   

11.
《Ceramics International》2020,46(10):16422-16430
Cobalt-doped g-C3N4 (Co-g-CN) nanolayers were prepared by a single-step thermal treatment with urea and cobalt nitrate. Different amounts of cobalt nitrate were tested to optimize the amount of cobalt dopant in the g-C3N4 (g-CN) matrix. Several characterization methods were used to explore the structural and optical properties along with the photoelectrochemical (PEC) performance. X-ray diffraction and Fourier transform infrared studies confirmed that g-CN nanolayers were successfully doped with cobalt without disturbing the basic 2-D structure and tris-triazine units of g-CN. Furthermore, microscopy images demonstrated that the cobalt effectively transformed the short nanosheets into long nanolayers. The cobalt-doping enhanced the visible absorption of g-CN and tuned the bandgap from 2.71 to 2.62 eV. An X-ray photoelectron spectroscopy (XPS) investigation discovered that cobalt entered into the g-CN network as Co2+ ions. XPS valence band spectra gave information on the modification in the valence and conduction band edge potentials due to cobalt doping. The photoluminescence intensity from the Co-g-CN samples was lesser than that from g-CN nanosheets, and the PEC activity of the Co-g-CN nanolayers was greater than that of as-prepared g-CN nanosheets. Co-g-CN samples prepared with 15 mg of cobalt nitrate hexahydrate showed a PEC performance of 3.2522 mA/cm2, which was greater than that of g-CN nanosheets (1.9246 mA/cm2). The better PEC performance was ascribed to the synergistic consequence of the higher visible absorption obtained by tuning the bandgap and the host–guest interactions between cobalt and g-CN.  相似文献   

12.
采用H2SO4与KMnO4为氧化剂,通过对热聚合法合成的原始石墨相氮化碳(g-C3N4)超声辅助氧化剥离,制备了超薄氧掺杂g-C3N4纳米片。基于HRTEM、XRD、AFM、XPS表征,考察了超声辅助氧化剥离对原始g-C3N4形貌、结构的影响;通过可见光催化降解刚果红分析了超薄氧掺杂g-C3N4纳米片的光催化性能;通过UV-vis-DRS、EIS、PL分析,探究了超薄氧掺杂g-C3N4纳米片光催化性能的增强机制。结果表明,对原始g-C3N4超声辅助氧化剥离6 h,可获得比表面积为58.45 cm2 g-1、厚度为1.08 nm的超薄氧掺杂g-C3N4纳米片;超薄氧掺杂g-C3N4纳米片(200 mg L-1)对刚果红(20 mg L-1)在120 min内可实现83%的降解,具有良好的光催化性能;与原始g-C3N4相比,超薄氧掺杂g-C3N4纳米片更有利于催化活性位点的暴露与光生载流子的分离传输,从而具有更好的光催化性能。  相似文献   

13.
《Ceramics International》2022,48(3):3293-3302
In this paper, a novel g-C3N4/ZnO composite microspheres (CZCM) with enhanced photocatalytic activity under visible light exposure were successfully prepared by a self-assembly method followed by calcination in the air. A hierarchical structure in which ZnO microspheres were closely covered with g-C3N4 nanosheets was constructed. The microstructure and photocatalytic activities of the CZCM were characterized. The photocatalytic property of CZCM was evaluated by degrading solution Methyl Orange (MO) and Tetracycline (TC). The effects of varied contents of g-C3N4 on the photocatalytic capability of CZCM were systematically investigated and the results show that the optimized CZ-15% sample exhibit much higher photocatalytic degradation efficiency than that of bare g-C3N4 or ZnO under identical conditions. The analysis of Photoluminescence (PL) and photocurrent (PC) independently conformed that the photo-induced electron-hole (e?-h+) pairs in the CZCM were effectively generated and responsible for the observed photocatalysis. The enhanced adsorption of visible-light and the effective charge separation on the surface of CZCM enabled significant improvement of photocatalytic performance. According to the experimental results and relative energy band levels of the two semiconductors, a possible photocatalysis mechanism for the reaction process is proposed.  相似文献   

14.
Hydrogen production by photolysis of water by sunlight is an environmentally-friendly preparation technology for renewable energy. Graphitic carbon nitride (g-C3N4), despite with obvious catalytic effect, is still unsatisfactory for hydrogen production. In this work, phosphorus element is incorporated to tune g-C3N4's property through calcinating the mixture of g-C3N4 and NaH2PO2, sacrificial agent and co-catalyst also been supplied to help efficient photocatalytic hydrogen production. Phosphorus (P) doped g-C3N4 samples (PCN-S) were prepared, and their catalytic properties were studied. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and ultraviolet diffuse reflection (UV-DRS) were used to study their structures and morphologies. The results show that the reaction rate of PCN-S is 318 μmol h−1 g−1, which is 2.98 times as high as pure carbon nitride nanosheets (CN) can do. Our study paves a new avenue, which is simple, environment-friendly and sustainable, to synthesize highly efficient P doping g-C3N4 nanosheets for solar energy conversion.  相似文献   

15.
Hydrogen production by photolysis of water by sunlight is an environmentally-friendly preparation technology for renewable energy. Graphitic carbon nitride (g-C3N4), despite with obvious catalytic effect, is still unsatisfactory for hydrogen production. In this work, phosphorus element is incorporated to tune g-C3N4's property through calcinating the mixture of g-C3N4 and NaH2PO2, sacrificial agent and co-catalyst also been supplied to help efficient photocatalytic hydrogen production. Phosphorus (P) doped g-C3N4 samples (PCN-S) were prepared, and their catalytic properties were studied. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and ultraviolet diffuse reflection (UV-DRS) were used to study their structures and morphologies. The results show that the reaction rate of PCN-S is 318 μmol·h-1·g-1, which is 2.98 times as high as pure carbon nitride nanosheets (CN) can do. Our study paves a new avenue, which is simple, environment-friendly and sustainable, to synthesize highly efficient P doping g-C3N4 nanosheets for solar energy conversion.  相似文献   

16.
g-C3N4/Ag-polypyrrole (PPy) visible-light photocatalysts were prepared in a simple way, in which g-C3N4 was decorated with Ag nanoparticles, and covered by PPy layer. Their photoactivity was evaluated by degradation of rhodamine B. Compared with g-C3N4, g-C3N4/Ag and g-C3N4/PPy, the enhanced photocatalytic activity was obtained and explained according to the improvement of visible-light absorption and reduction of recombination between photogenerated electron-hole pairs with the help of Ag nanoparticles and PPy. Their reusability was evaluated by recycling experiments. The structures and chemical compositions before and after photocatalytic degradation were compared. Moreover, a possible photocatalytic mechanism was discussed in detail.  相似文献   

17.
《Ceramics International》2022,48(15):21898-21905
Recently, there has been a significant interest in developing high-performance photocatalysts for removing organic pollutants from water environment. Herein, a ternary graphitic C3N4 (g-C3N4)/Ag3PO4/AgBr composite photocatalyst is synthesized using an in-situ precipitation-anion-exchange process and characterized by several spectroscopic and microscopic techniques. During the photocatalytic reaction, X-ray photoelectron spectroscopy clearly illustrated the formation of metallic Ag on the g-C3N4/Ag3PO4/AgBr composite surface. The ternary composite photocatalyst demonstrated an increased photoactivity under visible light (>420 nm), achieving a complete decolorization of methyl orange (MO) in 5 min. The ternary g-C3N4/Ag3PO4/AgBr hybrid was also applied to the 2-chlorophenol degradation under visible light, further confirming its excellent photocatalytic activity. In addition, quenching experiments revealed that holes (h+) and O2?– were the major attack species in the decolorization of MO. The enhanced photoactivity of g-C3N4/Ag3PO4/AgBr results from the efficient transfer/separation of photoinduced charges with the dual Z-scheme pathway and the charge recombination sites on the formed Ag particles.  相似文献   

18.
19.
A series of g-C3N4/ZnAl2O4 composites were prepared using a conventional calcination method and the heterostructures were systematically characterized. It was found that the combination of g-C3N4 with ZnAl2O4 significantly improve their photocatalytic activities. The optimum photocatalyst of composite is at 5% (wt%) of ZnAl2O4, whose degradation efficiency for methyl orange (MO) was 96% within 120 min under visible-light irradiation. The formation of heterojunction between g-C3N4 and ZnAl2O4 can facilitate efficient charge separation of photogenerated electron-hole pairs, which were confirmed by electrochemical impedance spectroscopy (EIS). As a result, the photocatalytic properties of composites were enhanced.  相似文献   

20.
《Ceramics International》2023,49(4):6213-6221
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-C3N4 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-C3N4 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   

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