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1.
As a potential material applied in the photocatalytic field, graphitic carbon nitride (g-C3N4) has attracted extensive attention for its advantages of visible-light response, excellent thermodynamic, and chemical stability. However, the photocatalytic performance of g-C3N4 is still limited in practical applications. Here, using a facile thermal polymerization method, unique W-doped foam g-C3N4 was synthesized to realize enhanced photocatalytic performance for the degradation of Rhodamine B and the evolution of hydrogen. Compared with pure foam g-C3N4, tungsten doping modified the foam g-C3N4 and efficiently improved its specific surface area, leading to enhanced photocatalytic performance. The average rate of hydrogen evolution was as high as 8818 μmol·h−1·g−1, which was better than most photocatalysts. This work proposes a new effective method and idea to modify g-C3N4 for improving its photocatalytic performance.  相似文献   

2.
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   

3.
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   

4.
It is very essential to grow efficient and abundant photocatalysts for overall water cracking to produce hydrogen. Ni3FeN nanosheets were synthesized by combining simple sol–gel and calcining methods using urea as nitrogen source. A heterostructure was constructed between Ni3FeN and g-C3N4 to enhance the absorption capacity of visible light. The reformed Z-scheme Ni3FeN/g-C3N4 heterojunction exhibited an excellent visible-light photocatalytic activity. The average hydrogen evolution rate of 5 wt% Ni3FeN/g-C3N4 composite is 528.7 μmol h−1 g−1 due to the Z-scheme Ni3FeN/g-C3N4 junction, which promotes the separation of photogenerated e/h+. Interestingly, the average H2 production of Ni3FeN/g-C3N4 is nearly 8.3 and 3.6 times higher than that of Fe4N/g-C3N4 and Ni4N/g-C3N4, respectively, indicating that bimetallic nitrides as cocatalysts are more conducive to enhancing the performance of photocatalysts. Importantly, the Ni3FeN/g-C3N4 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 Ni3FeN/g-C3N4 heterojunction improves the separation efficiency of photoinduced e/h+. This work provides a feasibility of the cocatalyst Ni3FeN for use in photocatalytic hydrogen production.  相似文献   

5.
《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   

6.
《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   

7.
Plasma processing technology, as a promising method to enhance photocatalytic activity of catalyst, is gradually attracting extensive interest from researchers. However, the main mechanism of plasma-treated photocatalyst on hydrogen production is not clear. In this work, 2D Ti3C2Tx MXene is selected as a co-catalyst of graphitic carbon nitride (g-C3N4), which carries out a plasma treatment (500°C) under N2/H2 atmosphere. Due to plasma treatment, there is a higher proportion Ti–O functional groups on surface of layered Ti3C2Tx MXene, especially for Ti4+. The obtained g-C3N4/p-Ti3C2Tx photocatalyst with sandwich-like structure shows an enhanced photocatalytic activity. The rate of hydrogen generation of CN/pTC3.0 sample without Pt co-catalyst is 25.4 and 2.4 times that of pure g-C3N4 and CN/TC3.0 samples, respectively. The improved photocatalytic activity is attributed to presence of Ti4+ due to plasma treatment, which can capture photo-induced electron from g-C3N4 and improve the separation of electrons and holes after visible light irradiation. The cyclic hydrogen production of the photocatalyst demonstrates good photocatalytic stability. In addition, this method of plasma treatment under N2/H2 atmosphere is feasible to develop a high-performance co-catalyst, which can be extended to other photocatalysts with two-dimensional structure for photocatalytic water-splitting applications.  相似文献   

8.
Porous-C3N4 with high photocatalytic activity of anionic dyes was successfully synthesized by a SiO2-template method. Its photocatalytic selectivity could easily be switched to cationic dye via a simple post-treatment in NaOH solution. Through careful investigation of influencing parameters (the photocatalytic performances, the structure and surface characteristics of the catalysts), the selective degradation of various dyes is closely related to the adsorption selectivity of the porous g-C3N4 catalysts, which originated from the different surface charge. This study provides a new insight into developing metal-free g-C3N4 photocatalyst with high efficiency and selectivity in environmental purification.  相似文献   

9.
《Ceramics International》2020,46(14):22683-22691
In order to overcome the problem of low photocatalytic rate of g-C3N4, the 3D FexS1-x/g-C3N4 heterojunction was prepared via a simple one-pot solid method. The X-Ray Diffraction (XRD) and scanning electron microscope (SEM) results demonstrated that the FexS1-x/g-C3N4 heterojunction was established and a g-C3N4 nanosheet was tightly bound to FexS1-x. Compared with g-C3N4 samples, FexS1-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 FexS1-x/g-C3N4 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 FexS1-x/g-C3N4 heterojunction was attributed to enhancement of the separation of e- and h+ in FeS2, which resulted from the effective conversion of FeS into FeS2 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. FexS1-x doping and heterojunction building improve the photocatalysis capacity of g-C3N4 and broaden the visible-light response of pure g-C3N4.  相似文献   

10.
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   

11.
Copper-nickel phosphides/ graphite-like phase carbon nitride (Cu3P-Ni2P/g-C3N4) composites were obtained through a facile one-pot in situ solvothermal approach. The coexistence of Cu3P and Ni2P plays an important role in enhancing the catalytic activity of g-C3N4. The 7 wt% Cu3P-Ni2P/g-C3N4 bimetallic phosphide photocatalyst demonstrates the best photocatalytic hydrogen (H2) evolution rate of 6529.8 μmol g−1 h−1, which is 80.7-fold higher than that of g-C3N4. The apparent quantum yield (AQE) was determined to be 18.5% at 400 nm over the 7% Cu3P-Ni2P/g-C3N4. This in situ growth strategy produced intimate contact interfaces, leading to a significantly promoted separation of charge carriers, and hence strengthened the photocatalytic H2 production. Moreover, the coexistence of Cu3P and Ni2P reduced the overpotential of H2 during the evolution process, further benefiting H2 production. Finally, the photocatalytic enhancement mechanism was proposed and verified by fluorescence and electrochemical analysis. This work provides a low-cost strategy to synthesize nonprecious bimetallic phosphides/carbon nitride photocatalyst with outstanding H2 production activity. © 2020 Society of Chemical Industry  相似文献   

12.
In this work, cobalt phosphide (CoP) nanoparticles were successfully decorated on an ultrathin g-C3N4 nanosheet photocatalysts by in situ chemical deposition. The built-in electric field formed by heterojunction interface of the CoP/g-C3N4 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-C3N4 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-C3N4 and was a visible light driven photocatalyst. In this process, NaH2PO2 and CoCl2 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 H2 evolution rate of 3.0 mol% CoP/g-C3N4 is about 15.1 μmol h−1. The photocatalytic activity and stability of the CoP/g-C3N4 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   

13.
《Ceramics International》2023,49(8):11989-11998
Utilization of graphitic carbon nitride (g–C3N4)–based materials for photocatalytic hydrogen production to alleviate energy problems is a hot topic of research nowadays, thus the design and synthesis of highly efficient g-C3N4 materials remains a significant challenge. Herein, the sulphur-doped hollow porous tubular g-C3N4 (S-HPTCN) was successfully synthesized by a facile environmentally friendly supramolecule self-assembly strategy. Photocatalytic H2 evolution tests show that the as-prepared optimal S-HPTCN achieved a high H2 production of up to 22.04 mmol g−1 h−1 with the turnover frequency (TOF) of 429.7 h−1 and the apparent quantum efficiency (AQE) of as high as 7.8% at wavelength of 420 nm. The enhancement of remarkable photocatalytic H2 performance is mainly attributed to the synergetic effect of morphology and elemental doping. This research provides an effective design idea of developing high-efficient g–C3N4–based material for solar to hydrogen.  相似文献   

14.
《Ceramics International》2020,46(5):5725-5732
2D heterojunction based on g-C3N4 nanosheets with other semiconductor nanosheets is a promising way to improve photocatalytic hydrogen evolution (PHE) activity over g-C3N4. However, current 2D heterojunction based on g-C3N4 are unsatisfactory due to their insufficient absorption of visible light and inefficient charge separation. In this work, Ag/TiO2/g-C3N4 nanocomposites based on 2D heterojunction coupling with Ag surface plasmon resonance (SPR) were synthesized by a method combining facile wetness impregnation calcination. The PHE activity of Ag/TiO2/g-C3N4 nanocomposites is attributed to the TiO2/g-C3N4 2D heterojunction and bare g-C3N4 nanosheet under visible light irradiation, indicating a cooperative effect between Ag and TiO2/g-C3N4 2D heterojunction. As a result of SPR effect, the composites strongly absorb visible light. In addition, the oscillating hot electrons from Ag can easily transfer to 2D heterojunction. This synergistic effect lead to sufficient visible light absorption and efficient charge separation of 2D heterojunction, which improved the PHE activity of g-C3N4. This work indicates that loading metal nanoparticles on 2D heterojunction as metal SPR-2D heterojunction nanocomposites may be a potential method for harvesting visible light for PHE.  相似文献   

15.
《Ceramics International》2020,46(17):26689-26697
Photocatalysis is one of the most promising ways to realize artificial photosynthesis. The biologically inspired photocatalysts with 3D flower-like structures have attracted much attention. In this study, an effective method for the synthesis of composite photocatalytic material, NH4TiOF3/TiO2/g-C3N4, with a 3D camellia-like structure, was developed. The 3D hierarchical structure of the composite material enabled multiple refractions and reflections of light within the catalyst, which greatly improved the efficiency of the sunlight harvesting. The combination of NH4TiOF3 and TiO2 also effectively reduced the electron-hole recombination in the g-C3N4. To evaluate its photocatalytic performance, the prepared nanostructured composite materials were tested for the water-splitting with simulated sunlight. It showed the hydrogen evolution at the rate of 3.6 mmol/g/h, which is 4.0 times faster than that from the pure g-C3N4. The composite materials exhibited excellent cycling stability. The detailed mechanism of the Z-scheme heterojunction was also discussed. The proposed synthesis route for the creation of 3D flower-like hierarchical composites provides a new effective technique for developing efficient, active, and stable composite photocatalysts for hydrogen production.  相似文献   

16.
The rational design of hierarchical heterojunction photocatalysts with efficient spatial charge separation remains an intense challenge in hydrogen generation from photocatalytic water splitting. Herein, a noble-metal-free MoS2/g-C3N4/ZnIn2S4 ternary heterostructure with a hierarchical flower-like architecture was developed by in situ growth of 3D flower-like ZnIn2S4 nanospheres on 2D MoS2 and 2D g-C3N4 nanosheets. Benefiting from the favorable 2D-2D-3D hierarchical heterojunction structure, the resultant MoS2/g-C3N4/ZnIn2S4 nanocomposite loaded with 3 wt% g-C3N4 and 1.5 wt% MoS2 displayed the optimal hydrogen evolution activity (6291 μmol g?1 h?1), which was a 6.96-fold and 2.54-fold enhancement compared to bare ZnIn2S4 and binary g-C3N4/ZnIn2S4, respectively. Structural characterizations reveal that the significantly boosted photoactivity is closely associated with the multichannel charge transfer among ZnIn2S4, MoS2, and g-C3N4 components with suitable band-edge alignments in the composites, where the photogenerated electrons migrate from g-C3N4 to ZnIn2S4 and MoS2 through the intimate heterojunction interfaces, thus enabling efficient electron-hole separation and high photoactivity for hydrogen evolution. In addition, the introduction of MoS2 nanosheets highly benefits the improved light-harvesting capacity and the reduced H2-evolution overpotential, further promoting the photocatalytic H2-evolution performance. Moreover, the MoS2/g-C3N4/ZnIn2S4 ternary heterostructure possesses prominent stability during the photoreaction process owing to the migration of photoinduced holes from ZnIn2S4 to g-C3N4, which is deemed to be central to practical applications in solar hydrogen production.  相似文献   

17.
《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   

18.
Hoang  Lan-Anh T.  Le  Nhat Duy  Nguyen  Trinh Duy  Lee  Taeyoon 《Topics in Catalysis》2023,66(1-4):194-204

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   

19.
Molybdenum doped graphitic carbon nitride (g-C3N4) 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-C3N4 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. CO2 photocatalytic reduction tests showed that the Mo-doped g-C3N4 catalysts exhibited considerably higher activity (the highest CO and CH4 yields of 887 and 123 μmol g 1-cat., respectively, after 8 h of UV irradiation.) compared with pure g-C3N4 from melamine.  相似文献   

20.
A BiVO4/2D g-C3N4 direct dual semiconductor photocatalytic system has been fabricated via electrostatic self-assembly method of BiVO4 microparticle and g-C3N4 nanosheet. According to experimental measurements and first-principle calculations, the formation of built-in electric field and the opposite band bending around the interface region in BiVO4/2D g-C3N4 as well as the intimate contact between BiVO4 and 2D g-C3N4 will lead to high separation efficiency of charge carriers. More importantly, the intensity of bulid-in electric field is greatly enhanced due to the ultrathin nanosheet structure of 2D g-C3N4. As a result, BiVO4/2D g-C3N4 exhibits excellent photocatalytic performance with the 93.0% Rhodamine B (RhB) removal after 40 min visible light irradiation, and the photocatalytic reaction rate is about 22.7 and 10.3 times as high as that of BiVO4 and 2D g-C3N4, respectively. In addition, BiVO4/2D g-C3N4 also displays enhanced photocatalytic performance in the degradation of tetracycline (TC). It is expected that this work may provide insights into the understanding the significant role of built-in electric field in heterostructure and fabricating highly efficient direct dual semiconductor systems.  相似文献   

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