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1.
In this study, B-doped g-C3N4 nanosheets (BCN) were prepared using a thermal-oxidative etching method, resulting in a semiconductor with a large specific surface area. The B-doping enhances the light absorption of graphitic carbon nitride(g-C3N4) and improves the photogenerated carrier lifetime. The optimal B-containing amount resuled in a hydrogen production rate of 1297 μmol g−1 h−1 for g-C3N4 nanosheets. Furthermore, zeolitic imidazolate framework (ZIF)67/BCN heterostructures were successfully obtained through simple mechanical grinding approaches. The BCN provided abundant active sites and contributed to excellent encapsulation on the surface of ZIF67. The obtained ZIF67/BCN photocatalyst displayed an H2 evolution rate of 3392 μmol g−1 h−1, attributed to forming type-II heterojunctions between ZIF67 and BCN. Moreover, the BCN exhibited a higher conduction band (CB) potential with ZIF67 than CN, resulting in more efficient light-driven charge separation between ZIF67 and BCN and enhanced photocatalytic performance. This work provides a meaningful reference for improving the activity of g-C3N4 photocatalysts.  相似文献   

2.
The photocatalytic hydrogen evolution performance of g-C3N4 was enhanced via the hybridization with montmorillonite (MMT) and using NiCoP as cocatalyst. The highest hydrogen-evolution rate from water splitting under visible-light irradiation observed over MMT/g-C3N4/15%NiCoP was 12.50 mmol g−1 h−1 under 1.0 mmol L−1 of Eosin Y-sensitization at pH of 11, which was ∼26.0 and 1.6 times higher than that of MMT/g-C3N4 (0.48 mmol g−1 h−1) and g-C3N4/15%NiCoP (7.69 mmol g−1 h−1). The apparent quantum yield at 420 nm reached 40.3%. The remarkably improved photocatalytic activity can be ascribed to the increased dispersion of g-C3N4 layers, staggered conduction band potentials between g-C3N4 and NiCoP, as well as the electrostatic repulsion originated from negatively charged MMT. This work demonstrates that MMT can be an outstanding support for the deposition of catalytically active components for photocatalytic hydrogen production.  相似文献   

3.
Engineering surface-active facets of metal cocatalysts is one of the most widely explored strategies to develop advanced photocatalysts and promote photocatalytic solar energy conversion. Here, the surface-active facets of Pd nanocrystals in Pd/g-C3N4 photocatalyst was related to the injection flow rate of PdCl2. When PdCl2 was injected at a low flow rate of 7.5 mL/h (7.5-Pd/g-C3N4), the Pd nanocrystals were uniformly dispersed onto the g-C3N4 with exposed low-index {100} and {111} surface-active facets. However, increasing the injection flow rate to 150 mL/h (150-Pd/g-C3N4) formed Pd nanocrystals where only the {100} surface-active facet was exposed. Under visible light irradiation, the 7.5-Pd/g-C3N4 nanocomposite exhibited excellent water splitting activity for hydrogen production (7.61 mmol g−1 h−1), which was significantly better than with the 150-Pd/g-C3N4 nanocomposite (3.3 mmol g−1 h−1). Theoretical calculations and experimental results confirm the importance of the {111} surface-active facets in the 7.5-Pd/g-C3N4 nanocomposite for promoting photocatalytic activity.  相似文献   

4.
Rational design of high-efficiency heterostructure photocatalyst is an effective strategy to realize photocatalytic H2 evolution from pure water, but remains still a considerable challenge. Herein, an anatase/rutile TiO2/g-C3N4 (A/R/CN) multi-heterostructure photocatalyst was prepared by a facile thermoset hybrid method. The combination of two type-II semiconductor heterostructures (i.e., A/R and R/CN) significantly improve the separation and transfer efficiency of photogenerated carriers of anatase TiO2, rutile TiO2 and g-C3N4, and A/R/CN photocatalyst with high activity is obtained. The optimal A/R/CN photocatalyst exhibits significantly increased photocatalytic overall water splitting activity with a rate of H2 evolution of 374.2 μmol g−1h−1, which is about 8 and 4 times that of pure g-C3N4 and P25. Moreover, it is demonstrated to be stable and retained a high activity (ca. 91.2%) after the fourth recycling experiment. This work comes up with an innovative perspective on the construction of multi-heterostructure interfaces to improve the overall photocatalytic water splitting performance.  相似文献   

5.
As an increasing number of photocatalysis are developed, non-noble metal photocatalysts that can be synthesized from earth-abundant and low-cost materials have received a great deal of attention. In this study, non-noble metal WS2/g-C3N4 photocatalysts were prepared by a facile one-pot synthesis. Varying masses of tungsten disulfide (WS2) were successfully loaded onto g-C3N4 and characterized by X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICP-OES), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). These results indicated that the WS2 was successfully synthesized and immobilized closely on the surface of g-C3N4 to form a sheet-like nanostructure. The H2 generation results showed that the optimal photocatalyst was 0.3-WCN because it had the highest photocatalytic H2 production of 154 μmol h−1g−1, which is 34 times higher than bare g-C3N4 and even higher than 0.3 wt% platinum-loaded g-C3N4. Additionally, the possible mechanism of the photocatalyst was studied by photoluminescence (PL), UV–vis diffuse reflectance spectroscopy (UV–vis DRS) and photoelectrochemical tests, which showed that the WS2 played a key role in improving the efficiency of separation and migration of the photogenerated carriers in g-C3N4.  相似文献   

6.
Fabricating 0D/2D heterojunctions is considered to be an efficient mean to improve the photocatalytic activity of g-C3N4, whereas their applications are usually restricted by complex preparation process. Here, the 0D/2D SnO2/g-C3N4 heterojunction photocatalyst is prepared by a simple one-step polymerization strategy, in which SnO2 nanodots in-situ grow on the surface of g-C3N4 nanosheets. It shows the outstanding photocatalytic H2 production activity relative to g-C3N4 under the visible light, which is due to the formation of 0D/2D heterojunction significantly contributing to the separation of photogenerated charge carriers. In particular, the H2 production rate over the optimal SnO2/g–C3N4–1 sample is 1389.2 μmol h−1 g−1, which is 6.06 times higher than that of g-C3N4 (230.8 μmol h−1 g−1). Meanwhile, the AQE value of H2 production over the SnO2/g–C3N4–1 sample reaches up to a maximum of 4.5% at 420 nm. This work develops a simple approach to design and fabricate g–C3N4–based 0D/2D heterojunctions for the high-efficiency H2 production from water splitting.  相似文献   

7.
Novel PdAg bimetallic alloy nanoparticle modified graphitic carbon nitride (g-C3N4) nanosheet was designed and prepared by an in situ chemical reduction procedure. By optimizing the loading content of the PdAg alloy NPs, the PdAg/g-C3N4 composite photocatalyst showed a champion photocatalytic hydrogen generation rate of 3.43 mmol h−1 g−1, and the apparent quantum yield (AQY) was determined to be 8.43% at 420 nm. Moreover, the photoluminescence and photoelectrochemical experimental results suggest that a higher separation efficiency of photo-induced charge carriers (e- and h+) was obtained after loading PdAg alloy NPs on g-C3N4. The experimental outcomes indicate that there is a synergistic effect formed between PdAg and g-C3N4, which could significantly promote the charge transfer photo-induced charge carriers in the hybrid sample. A reasonable catalytic mechanism for the enhanced photocatalytic performance of the composite photocatalyst was proposed and verified by TRPL measurement, which could be taken as a guidance for the development of novel high performance catalytic system.  相似文献   

8.
Facilitating the separation of photoexcited electron-hole pairs and enhancing the migration of photogenerated carriers are essential in photocatalytic reaction. CoS/g-C3N4/NiS ternary photocatalyst was prepared by hydrothermal and physical stirring methods. The optimized ternary composite achieved a hydrogen yield of 1.93 mmol g?1 h?1, 12.8 times that of bare g-C3N4, with an AQE of 16.4% at 420 nm. The enhanced photocatalytic activity of CoS/g-C3N4/NiS was mainly ascribed to the synergistic interaction between the Z-scheme heterojunction constructed by CoS and g-C3N4 and the NiS co-catalyst featuring a large amount of hydrogen precipitation sites, which realized the efficient separation and migration of photogenerated carriers. In addition, the CoS/g-C3N4/NiS heterojunction-co-catalyst system exhibited excellent photocatalytic stability and recyclability.  相似文献   

9.
In this report, a novel g-C3N4/Au/BiVO4 photocatalyst has been prepared successfully by assembling gold nanoparticles on the interface of super-thin porous g-C3N4 and BiVO4, which exhibits outstanding photocatalytic performance toward hydrogen evolution and durable stability in the absence of cocatalyst. FESEM micrograph analysis suggested that the intimate contact between Au, BiVO4, and g-C3N4 in the as-developed photocatalyst allows a smooth migration and separation of photogenerated charge carriers. In addition, the XRD, EDX and XPS analysis further confirmed the successful formation of the as-prepared g-C3N4/Au/BiVO4 photocatalyst. The photocatalytic hydrogen production activity of the developed photocatalyst was evaluated under visible-light irradiation (λ > 420 nm) using methanol as a sacrificial reagent. By optimizing the 5-CN/Au/BiVO4 composite shows the highest H2 evolution rate (2986 μmolg−1h−1), which is 15 times higher than that of g-C3N4 (199 μmolg−1h−1) and 10 time better than bare BiVO4 (297 μmolg−1h−1). The enhancement in photocatalytic activity is attributed to efficient separation of the photoexcited charges due to the anisotropic junction in the g-C3N4/Au/BiVO4 system. The enhancement in photocatalytic activity is attributed to efficient separation of the photoexcited charges due to the anisotropic junction in the g-C3N4/Au/BiVO4 system.  相似文献   

10.
The design and development of noble metal-free, low-cost and stable co-catalyst are of great significance to the practical application of photocatalysts. In this work, the Mo incorporated Ni nanosheets (MoNi NSs) are successfully prepared and loaded onto g-C3N4 via a simple and controllable method. The controlled loading of MoNi NSs with an optimal Mo intake can greatly enhance the photocatalytic H2-evolution property of g-C3N4 (Mo0.25Ni0.75/CN5). Specifically, the Mo0.25Ni0.75/CN5 exhibits the highest photocatalytic H2-evolution rate of 273.2 μmol h−1 (5464 μmol h−1 g−1), which is the highest rate under one-solar light in the g-C3N4 systems coupled with noble-metal-free co-catalysts. The greatly enhanced photocatalytic H2-evolution activity of MoNi/g-C3N4 is attributed to the role of MoNi as an outstanding co-catalyst to promote the carriers’ separation and transfer, and accelerate the surface H2 evolution reaction (HER).  相似文献   

11.
Here we report a 2D-2D heterostructure of g-C3N4/UMOFNs photocatalysts via mechanical grinding two kinds of two-dimensional nanosheets of g-C3N4 nanosheets and UMOFNs, which exhibits enhanced H2 evolution from water with simulated solar irradiation. g-C3N4 nanosheets are in close contact with UMOFNs, and there is a certain interaction between them, showing the effect of superimposition on the two-dimensional layer. The 2D-2D heterostructure offers a maximal photocatalytic hydrogen production activity of 1909.02 μmol g−1 h−1 with 3 wt% of UMOFNs, which is 3-fold higher than that of g-C3N4 nanosheets (628.76 μmol g−1 h−1) and 15-flod higher than that of bulk g-C3N4 (124.30 μmol g−1 h−1). The significant increasement of photocatalysis is due to 2D-2D heterostructure possessing a short charge transfer distance and large contact area between g-C3N4 and UMOFNs. The highly dispersed NiO, CoO and π-π bonds in UMOFNs of 2D-2D structure also promote charge transfer and enhance the photocatalytic activity.  相似文献   

12.
Controlled integration of metal-based sulfides with phosphides possessing strong coupling effects is a promising way to accelerate electron transfer by modulating the electronic structures of the host species. In this work, a c-doped Ni3S4/Ni2P (C@Ni3S4/Ni2P) hybrid co-catalyst produced by in situ sulfuration and phosphidation of Ni-MOF was decorated on g-C3N4 and subsequently used for photocatalytic H2 evolution under visible-light irradiation. Among the prepared composites tested herein, the optimized g-C3N4/C@Ni3S4/Ni2P-30 composite showed the highest H2 evolution rate (14.49 mmol g−1 h−1) with 1.0 mmol L−1 of Eosin Y (EY)-sensitization, which is 10 times higher than that of pristine g-C3N4 (1.33 mmol g−1 h−1). The enhanced photocatalytic activity of this composite can be attributed to: (i) electronic interactions between Ni2P and Ni3S4 (which synergistically increased the electron transfer rate) and (ii) staggered band alignment of excited-stated EY, g-C3N4, Ni3S4, and Ni2P. This work may provide some perspectives for utilization of MOF-derived hybrid co-catalysts as substitutes of noble metals for effective photocatalytic H2 evolution.  相似文献   

13.
In this work, a series of Ag/AgX (X = Cl, Br, I)/g-C3N4 (Ag/AgX/CN) composites were successfully fabricated by an in-situ solid phase method. The morphology and structure, photoluminescence and photoelectrochemical properties of composites were investigated in detail. The as-prepared Ag/AgX/CN composites were used as H2 evolution photocatalysts under visible-light irradiation with a sacrificial agent. The experimental results revealed that Ag/AgI/CN-4 composite possesses highest-H2 evolution rate (up to 59.22 μmol g−1 h−1) which are approximately 31 times higher than that of pure g-C3N4 (1.94 μmol g−1 h−1). In addition, Ag/AgCl/CN-4 and Ag/AgBr/CN-4 composites also present high photocatalytic activities yielding, 26.39 and 18.05 μmolH2 g−1 h−1, respectively. The enhanced photocatalytic activities of Ag/AgI/CN-4 composite might be attributed to the synergistic effect between Ag/AgI nanoparticles and g-C3N4 and the localized surface plasmon resonance effect of metallic Ag. Moreover, Ag/AgI/CN-4 composite showed excellent recyclability and stability after five cycling photocatalytic tests (about 25 h). Furthermore, the possible photocatalytic mechanism of Ag/AgI/CN composites is proposed.  相似文献   

14.
Although graphitic carbon nitride (g-C3N4) is widely used for photocatalytic hydrogen production, its practical application is restricted by the high recombination rate of photoinduced electron-hole pairs and limited active sites. In this work, holey ultrathin g-C3N4 nanosheets (HCN NSs) with rich active sites are prepared, followed by the growth of 1T-MoS2 NSs on their surfaces to construct 2D/2D 1T-MoS2/HCN heterostructure. Due to the high surface area and abundant hydrogen active sites of the hybrid, large and intimate 2D nanointerface between MoS2 and HCN, hydrogen ion adsorption and charge separation/transport ability are greatly enhanced. As a result, 1T-MoS2/HCN-4 with the optimal 1T-MoS2 content of 8 wt% displays the highest H2 production rate of 2724.2 μmol?1 h?1 g?1 under simulated solar light illumination with apparent quantum efficiency of 8.1% (λ = 370 nm). Moreover, the 1T-MoS2/HCN-4 hybrid manifests improved stability after a long-time test. This study opens the door to design highly-efficient g-C3N4 based 2D/2D heterostructures for photocatalytic H2 production.  相似文献   

15.
Ceria dioxide supported on graphitic carbon nitride (CeO2/g-C3N4) composites were facilely synthesized to be application for photocatalytic hydrogen (H2) generation in this present work. The physical and chemical properties of CeO2/g-C3N4 nanocomposites were determined via a series of characterizations. The CeO2/g-C3N4 composites prepared by facile thermal annealing and rotation-evaporation method exhibit excellent photocatalytic H2 evolution with visible-light illumination. The best hydrogen generation rate of CeO2/g-C3N4 composite with 1.5 wt% Pt is 0.83 mmol h−1 g−1, which is almost same as that of composite with 3 wt% Pt prepared by simple physical mixing method. The significantly developed photocatalytic activity of CeO2/g-C3N4 composite is majorly ascribed to the stronger interfacial effects with the more visible-light absorbance and faster electron transfer. This work reveals that construction of the CeO2/g-C3N4 composite with high disperse and close knit by the facile thermal annealing and rotation-evaporation method could be an effective method to achieve excellent photocatalytic hydrogen evolution performance.  相似文献   

16.
To create hybrid composites for highly effective photocatalytic hydrogen evolution reactions, the photogenerated charge separation efficiency at the hybrid interface and the surface reaction kinetics at the reactive sites are key factors. In this work, CoFe hydroxide nanosheets prepared by dealloying were first mixed with graphitic carbon nitride (g-C3N4) to synthesize a CoFe2O4/g-C3N4 composite with strong Co-N bonds at the interface by a simple hydrothermal method. It was found that the presence of Co-N bonds between the components in the composites enhances the separation and transfer by photogenerated carriers at the composite interface. Furthermore, the presence of Co-N bonds enhanced the synergistic effect of the hybrid, which significantly boosts their photocatalytic performance in comparison to their counterparts. Under full-spectrum light, the composite photocatalyst has a greater efficiency of photocatalytic water H2 evolution (6.793 mmol/g−1·h−1) and exceptional stability when compared to pure g-C3N4 (0.236 mmol/g−1·h−1) and CoFe2O4 (0.088 mmol/g−1·h−1). Under visible irradiation, the photocatalytic activity of the composite (0.556 mmol/g−1·h−1) for H2 evolution increased by factors of 28.37 and 75.8 when compared to pure g-C3N4 and CoFe2O4, respectively.  相似文献   

17.
Herein, highly efficient and cost effective solar photocatalytic water splitting for hydrogen (H2) generation was achieved by modified g-C3N4. Visible light absorption of g-C3N4 was enhanced by decorating g-C3N4 matrix with silver nanoparticles (Ag). Moreover, incorporation of carbon nanotubes (CNTs) in Ag/g-C3N4 facilitated photocatalytic performance through efficient separation and transfer of photogenerated e-h pairs (charges) in Ag/g-C3N4 that consequently generated very pure and significant H2. Among several tested ratios (wt. %) of Ag/g-C3N4/CNTs, 1.82 (Ag/g-C3N4) and 2.00 (and Ag/g-C3N4/CNTs) were found to be highly efficient that harvested maximum visible-light and produced H2 @1.48 mmol h−1 and 1.78 mmol h−1. We witnessed distinctive role of CNTs as an electron collector and carrier to separate photogenerated e-h pairs to facilitate photocatalysis for H2 generation together with possible utility of Ag and CNTs doped materials with regard to energy transformation.  相似文献   

18.
Graphite-like carbon nitride (g-C3N4) has been regarded as a promising photocatalyst for solar-to-chemical conversion. Nevertheless, the narrow absorption of light extremely limited its photocatalytic performance under near-infrared (NIR) irradiation. Herein, the Cu7.2S4 with outstanding NIR absorption was successfully introduced to g-C3N4 nanosheets through a simple in-situ growth procedure. As expected, the constructed Cu7.2S4/g-C3N4 (CSCN) photocatalysts exhibit superior H2 production activity of 82 μmol g−1 h−1 under NIR light irradiation (λ > 800 nm), which outperforms currently reported g–C3N4–based NIR-driven H2 production systems. Especially, the optimal sample CSCN-5 displays a robust activity of 66 μmol g−1 h−1 at λ = 850 nm monochromatic light irradiation. The excellent photocatalytic performance is linked to the extended optical absorption as well as the efficient separation efficiency of photoinduced carriers, which are evidenced by the UV-visible absorption spectroscopy and photoelectrochemical test. This work provides an effective approach for constructing a Cu7.2S4/g-C3N4 photocatalytic system for the transformation of NIR solar energy into hydrogen.  相似文献   

19.
The use of multi-pore nanostructured g-C3N4 photocatalysts is an efficient approach to separate photogenerated charge carriers and increase visible light photocatalytic performance. Recent progress has yielded nanostructured material through hard templating, which limits potential applications. Integrating the 2D building block into multidimensional porous structures remains a significant challenge in scalable production. Herein, a novel technique based on P407 bubble clusters templating and fixation by freezing is described for the first time to fabricate a 3D opened-up macroporous g-C3N4 nanostructures for photocatalytic H2 evolution. Three-dimensional hierarchical nanostructures provide more contact active sites and synergistically promote the creation of heterogeneous catalytic interfaces. This feature is very useful for understanding the transfer path of photoinduced charges as well as the origins of the high charge separation efficiency in photocatalytic reactions, thus yielding a remarkable visible light-induced H2 evolution rate of 4213.6 μmol h−1 g−1, which is nearly 5.6 times (716 μmol h−1 g−1) higher than that of lamellar bulk g-C3N4. This newly developed approach offers a promising alternative to synthesize broad-spectral response 3D hierarchal g-C3N4 nanostructures and can be extended to assemble other functional nanomaterials as building blocks into macroscopic configurations coupled with electronic modulation strategy simultaneously.  相似文献   

20.
A designed type-II heterojunction photocatalyst, NiSe2/Cd0.5Zn0.5S (NiSe2/CZS), was successfully synthesized and it exhibits outstanding photocatalytic hydrogen evolution performance. The optimal loading amount of NiSe2 on Cd0.5Zn0.5S is 13 wt %, and the corresponding hydrogen production rate is approximately 121.01 mmol g?1 h?1 under visible light. The heterojunction structure between Cd0.5Zn0.5S and NiSe2 promoted the separation of photogenerated electron-hole pairs, effectively suppressed the photogenerated carrier recombination and endowed the material with excellent interfacial charge transfer properties, thus improving the photocatalytic performance.  相似文献   

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