| As a new kind two dimentional semiconductor photocatalyst, the graphited carbon nitride(g-C3N4) become a hot researching materials due to its good physical and chemical stability, abundant source and low-cost raw meterials, easy to be modified and appropriate energy band structure. Graphited C3N4 has a great research and application value in the field of photocatalytic splitting water to produce hydrogen and degrading organic pollutants. In this paper, some special morphology g-C3N4 were prepared by different methods, which were doped and composited simultaneously. Finally, the photocatalytic activity meterials were synthetized successfully. It will be an important reference for researches and applications of g-C3N4. The main research works in this paper are as follow:Li Cl and KCl was used as the heating medium to calcinate the barbituric acid and dicyandiamide mixture precursor and synthetize the carbon-doped g-C3N4(denoted as mg-CN) which posses a 2D morphology. Experiments prove that the as-prepared samples are builded as(C3N4)x-(C7N7)y structure, and the layer structure can be observed obviously. Samples have the same crystal phase strcture and functional groups with g-C3N4. mg-CN shifts to red and improves visible light absorption capacity obviously compared with g-C3N4 from the UV-vis spectra. The BET surface area can be greatly increased by ionothermal copolymerization. The PL spectrum of samples shows that the fluorescence intensity of samples prepared by ionothermal copolymerization is significantly lower than original g-C3N4, indicating a lower electron-hole recombination rate. When the amount of barbituric acid is 0.52 g and the dicyandiamide is 2.0 g, the as-prepared sample has the best photocatalytic property, which can improve the catalytic efficiency from 41.5% up to 83.8% in 90 min. Cyclic degradation experiments also illustrate that the as-prepared photocatalyst has a high degradation rate after 4 times recycled degradation experiments.The above mg-CN was composited with Bi OBr by the chemistry in situ growth method in water bath. Experiments results show that mg-CN particles adhere on the surface of Bi OBr nanosheets, and mg-CN/Bi OBr contain the main functional groups of g-C3N4 and Bi OBr. The BET area is increased with increasing the amount of mg-CN, and also the visible absorption ability is increased. The degradation Rh B solution experiments under visible light for all of the samples show that 30 wt.%, 50 wt.% and 70 wt.%mg-CN/Bi OBr can totally decompose Rh B solutions in 6 min. However, 50 wt.%mg-CN/Bi OBr has the best k value, indicating the largest coordination can be formed when the weight ratio of mg-CN and Bi OBr is 1:1. A cycling experiment of the photocatalyst shows it has a good stability. Photocurrent tests and PL spectra indicate that the recombination of photo-generated electron-hole is inhibited by hybriding Bi OBr with mg-CN.The spherical morphology g-C3N4 is prepared by a yeast-template method, which simply calcine the cultured yeast and dicyandiamide mixture. The as-prepared samples have the same crystal phase structure with g-C3N4. Some spherical particals and holes can be observed in the samples prepared by the yeast-template method. The FTIR spectra show the similar functional groups between g-C3N4 and as-prepared samples, which can be distinguished by the extra organic functional groups absorption peaks. The UV-vis spectra show that the samples prepared by yeast-template method have stronger visible absorption ability, and the absorption edge is also increased by increasing the proportion of yeast. However, the yeast-template can damage the semiconductor feature of g-C3N4, which is not good for its application. The BET surface areas of samples are decreased by yeast-template method. The PL spectra indicate that the as-prepared samples have a lower electron-hole pair recombination rate. The result about catalytic degradating Rh B under visible light shows that the photocatalytic property of sample prepared by yeast-template method is decreased. |
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