In this study, a facile and benign protocol was introduced for the immobilization of SiO2 nanoparticles onto g-C3N4 nanosheets. The corresponding nanocomposite (SiO2/g-C3N4) was characterized by various techniques, including X-ray diffraction, transmission electron microscopy, thermo-gravimetric analysis, and Fourier transform infrared spectra. The activity of a SiO2/g-C3N4 nanocomposite was investigated in C–C bond formation reaction. The Friedel–Crafts 3-indolylation reaction of isatin with indole derivatives was investigated in the presence of a catalytic amount of SiO2/g-C3N4 nanocomposite at ambient temperature in water as a green medium. The results showed that the corresponding products were obtained in good to excellent yields. In addition, the electron-releasing groups in the R1 position of the indole ring or electron-withdrawing groups on the R4 position of isatin gave excellent yields (91–95%). Some advantages of this method include short reaction time, excellent yields, easy work-up, and the use of water as a green solvent.
Although metal-organic frameworks(MOFs) have been widely reported as precursors for obtaining various porous materials in recent years, the limited MOF types and monofunctional active site of MOF-based catalysts remain to be hard to crack. Herein, bimetallic MOFs, MCo-ZIFs stabilized by graphitized carbon nitride(g-C3N4) and their pyrolytic MxCo3O4/g-C3N4 hybrids(M=Zn, Cu, Fe, Ni) have been designedly synthesized. The obtained MxCo3O4/g-C3N4 hybrids display synergistic photothermal effect from both MxCo3O4 and g-C3N4 under visible light irradiation. Significantly, the solution temperature can be heated from room temperature(20℃) to 66℃ after 40 min irradiation. Therefore, the catalytic activity of MxCo3O4/g-C3N4 exceeds those of most reported catalysts under mild reaction conditions. The optimal ZnxCo3O4/g-C3N4 catalyst realizes 96% conversion and 75% selectivity toward styrene oxide within 20 min. Incredibly, the CuxCo3O4/g-C3N4 could achieve up to 89% selectivity toward styrene oxide. To our knowledge, this is the first report about the novel photothermal effect of ZIFs-derived metal oxides. 相似文献
The rational construction of a high-efficiency stepscheme heterojunctions is an effective strategy to accelerate the photocatalytic H2.Unfortunately,the variant energy-level matching between two different semiconductor confers limited the photocatalytic performance.Herein,a newfangled graphitic-carbon nitride(g-C3N4)based isotype step-scheme heterojunction,which consists of sulfur-doped and defective active sites in one microstructural unit,is successfully developed by in-situ polymerizing N,N-dimethylformamide(DMF)and urea,accompanied by sulfur(S)powder.Therein,the polymerization between the amino groups of DMF and the amide group of urea endows the formation of rich defects.The propulsive integration of S-dopants contributes to the excellent fluffiness and dispersibility of lamellar g-C3N4.Moreover,the developed heterojunction exhibits a significantly enlarged surface area,thus leading to the more exposed catalytically active sites.Most importantly,the simultaneous introduction of S-doping and defects in the units of g-C3N4 also results in a significant improvement in the separation,transfer and recombination efficiency of photo-excited electron-hole pairs.Therefore,the resulting isotype step-scheme heterojunction possesses a superior photocatalytic H2 evolution activity in comparison with pristine g-C3N4.The newly afforded metal-free isotype step-scheme heterojunction in this work will supply a new insight into coupling strategies of heteroatoms doping and defect engineering for various photocatalytic systems. 相似文献
Research on Chemical Intermediates - NiO@g-C3N4 as an efficient catalyst for the synthesis of spirooxindole derivatives was prepared by impregnation of g-C3N4 with NiO nanoparticles and... 相似文献
Environmental pollution, especially water pollution, is becoming increasingly serious. Organic dyes are one type of the harmful pollutants that pollute groundwater and destroy ecosystems. In this work, a series of graphitic carbon nitride (g-C3N4)/ZnO photocatalysts were facilely synthesized through a grinding method using ZnO nanoparticles and g-C3N4 as the starting materials. According to the results, the photocatalytic performance of 10 wt.% CN-200/Z-500 (CN-200, which g-C3N4 was 200 kGy, referred to the irradiation metering. Z-500, which ZnO was 500 °C, referred to the calcination temperature) with the CN-200 exposed to electron beam radiation was better than those of either Z-500 or CN-200 alone. This material displayed a 98.9% degradation rate of MB (20 mg/L) in 120 min. The improvement of the photocatalytic performance of the 10 wt.% CN-200/Z-500 composite material was caused by the improvement of the separation efficiency of photoinduced electron–hole pairs, which was, in turn, due to the formation of heterojunctions between CN-200 and Z-500 interfaces. Thus, this study proposes the application of electron-beam irradiation technology for the modification of photocatalytic materials and the improvement of photocatalytic performance. 相似文献
Russian Journal of Physical Chemistry A - Graphitic carbon nitride nanosheets (g-C3N4 NS) are an important material with many promising practical applications. However, construction of g-C3N4 NS... 相似文献
Heterogeneous catalysts have been developed for C-C coupling reactions, but stand low activity and always proceed under harsh conditions. Photocatalytic Stille cross-coupling reaction as a green catalytic method for C-C bond formation is of great interest for a wide range of scientists but still lacks stable and highly efficient catalysts. Herein, we have designed an Au nanoparticle-graphitic carbon nitride heterojunction as an outstanding photocatalyst for artificial photosynthesis in Stille cross-coupling reaction. The interface effect between metal and semiconductor makes electron rectify and prevents the recombination of electron-hole pairs. Moreover, the efficiency of Au nanoparticle catalysts could be adjusted by gold contents. Thus the turnover frequency(TOF) value reached the highest level of 788 h-1 over the optimal heterojunction catalyst. Most importantly, the C-C bond formation reaction has been proved to be carried out well under visible light irradiation, indicating the low-cost organic synthesis process. Further analysis confirmed the stability and general application of our heterogeneous Au nano-heterojunction catalyst. 相似文献
Graphitic carbon nitride (g-C3N4) has been widely studied as a visible light responsive photocatalyst in recent years, due to its facile synthesis, low cost, high stability, and appropriate bandgap/band positions. In this review, we firstly introduce and compare various exfoliation approaches of bulk g-C3N4 into ultrathin g-C3N4 nanosheets. Then, many modification strategies of g-C3N4 nanosheets are also reviewed, including heterojunction construction, doping, defect control, and structure design. Thereafter, the charge transfer mechanism in g-C3N4 nanosheets based heterojunctions is present, e.g., Z-scheme, S-scheme and other forms. Besides, the photocatalytic applications of g-C3N4 nanosheets based photocatalysts are summarized including environmental remediation, energy generation and storage, organic synthesis, and disinfection. This review ends with a summary and some perspectives on the challenges and new directions in exploring g-C3N4 nanosheets-based photocatalysts. 相似文献
Porous graphitic carbon nitride (g-C3N4) was prepared by dicyandiamide and urea via the pyrolysis method, which possessed enhanced visible-light-driven photocatalytic performance. Its surface area was increased from 17.12 to 48.00 m2/g. The porous structure not only enhanced the light capture capacity, but also accelerated the mass transfer ability. The Di (Dicyandiamide)/Ur (Urea) composite possessed better photocatalytic activity for Rhodamine B in visible light than that of g-C3N4. Moreover, the Di/Ur-4:5 composite showed the best photoactivity, which was almost 5.8 times that of g-C3N4. The enhanced photocatalytic activity showed that holes and superoxide radical played a key role in the process of photodegradation, which was ascribed to the enhanced separation of photogenerated carriers. The efficient separation of photogenerated electron-hole pairs may be owing to the higher surface area, O dopant, and pore volumes, which can not only improve the trapping opportunities of charge carriers but also the retarded charge carrier recombination. Therefore, it is expected that the composite would be a promising candidate material for organic pollutant degradation. 相似文献