类石墨烯结构二硫化钼纳米片的制备及其催化性能研究

发布时间：2018-03-23 08:33

本文选题：二硫化钼纳米片　切入点：磷酸银　出处：《长安大学》2017年硕士论文　论文类型：学位论文

【摘要】：二硫化钼(MoS_2)是具有类石墨烯结构的二维(2D)层状材料,属于过渡金属硫化物MX2范畴,其中M和X分别对应于过渡金属和硫属元素。它们之间以共价键的方式结合,各分子层之间存在范德华力。因其特殊的层状结构,在催化、电学、光学等领域表现出不同于块体材料的优异性能,引起了研究人员的关注。本文针对类石墨烯结构MoS_2纳米片的制备以及其催化性能进行了研究。以商业MoS_2为原料,采用低能球磨和超声联用的方法,成功剥离出MoS_2纳米片。通过XRD、SEM、HRTEM和AFM等一系列表征方法,对其晶体结构和形貌进行了分析,并讨论了不同制备工艺参数对实验结果的影响。结果表明:通过上述方法制备的MoS_2纳米片厚度为1-3层,且形貌均一,稳定性好。其最佳制备条件为:以NMP为溶剂,球磨时间为24 h,超声时间为6 h。采用球磨法制备了Ag_3PO_4/MoS_2纳米片复合催化剂,并对制备的样品的结构和相关性能进行了测试分析。结果显示:以亚甲基蓝作为污染物,在可见光照射25 min后,Ag_3PO_4/MoS_2纳米片复合材料对其降解率最高可达到93%,而纯Ag3PO4对其降解率仅为80.55%。由重复试验可知,MoS_2纳米片的加入有效改善了Ag3PO4的稳定性。采用高温热解三聚氰胺制得g-C_3N_4粉体,通过球磨法将g-C_3N_4与MoS_2纳米片成功复合。通过对样品的结构和光催化性能表征后得知,g-C_3N_4和MoS_2纳米片形成异质结构,有效提高了g-C_3N_4的光催化性能。其中,以罗丹明B作为污染物,在可见光照射120 min后,MoS_2纳米片的掺量为g-C_3N_4质量的2%的样品对其降解率最高,降解率为97%。同时,光生空穴在该光催化反应过程中起主要作用。通过球磨法制备了g-C_3N_4/MoS_2纳米片/GO三元复合材料,并对其结构和相关性能进行了测试分析。加入MoS_2纳米片和GO后,使得g-C_3N_4的颗粒尺寸减小,块层变薄。同时,GO作为载体,为g-C_3N_4/MoS_2纳米片异质结构提供更多光子能量和光催化反应活性位点,从而提高了g-C_3N_4的光催化性能。相比于单一的MoS_2纳米片和GO,两者的协同作用能更显著的改善g-C_3N_4的光催化性能。其中,80/20MG样品在可见光下降解Rhb的速率分别是g-C_3N_4、0.3%MN和0.3%NG的2.9倍、1.7倍和1.6倍。
[Abstract]:Molybdenum disulfide (MoS _ 2) is a two-dimensional (2-D) layered material with graphene like structure, which belongs to the MX2 category of transition metal sulphides, in which M and X correspond to transition metals and sulfur elements, respectively. There is van der Waals force between the molecular layers. Due to its special layered structure, it exhibits excellent properties different from bulk materials in the fields of catalysis, electricity, optics, etc. In this paper, the preparation and catalytic performance of graphene like MoS_2 nanoparticles were studied. Commercial MoS_2 was used as raw material, and the method of low energy ball milling combined with ultrasonic was used. The MoS_2 nanocrystals were successfully stripped. The crystal structure and morphology were analyzed by means of a series of characterization methods, such as XRD-SEMTEM and AFM. The effects of different preparation parameters on the experimental results were also discussed. The results showed that the MoS_2 nanoparticles prepared by the above method had a thickness of 1-3 layers, uniform morphology and good stability. The optimum preparation conditions were as follows: NMP as solvent. The ball milling time was 24 h and the ultrasonic time was 6 h. The composite catalyst of Ag_3PO_4/MoS_2 nanoparticles was prepared by ball milling method. The structure and related properties of the prepared samples were tested and analyzed. The results showed that methylene blue was used as pollutant. After 25 min of visible light irradiation, the degradation rate of Ag-S _ 3PO _ 4 / MoS _ 2 nanochip composite can reach 93%, but the degradation rate of pure Ag3PO4 is only 80.55%. The repeated experiments show that the addition of MoS _ 2 nanoparticles can effectively improve the stability of Ag3PO4, and the stability of Ag3PO4 is improved by pyrolysis at high temperature. G-C_3N_4 powder prepared from melamine, The structure and photocatalytic properties of g-C_3N_4 and MoS_2 nanoparticles were characterized by ball milling method. It was found that the structure and photocatalytic properties of g-C_3N_4 and MoS_2 nanoparticles were heterogeneous, which effectively improved the photocatalytic performance of g-C_3N_4. Among them, Rhodamine B was used as a pollutant. After 120 min of visible light irradiation, the sample containing 2% of the mass of g-C_3N_4 has the highest degradation rate, and the degradation rate is 97.At the same time, The photogenerated holes play an important role in the photocatalytic reaction. The g-C_3N_4/MoS_2 nanochip / go ternary composites were prepared by ball milling, and their structures and properties were tested and analyzed. The particle size of g-C_3N_4 is reduced and the block layer is thinned. At the same time, go is used as the carrier to provide more photon energy and active sites for photocatalytic reaction for g-C_3N_4/MoS_2 nanocrystalline heterostructures. As a result, the photocatalytic activity of g-C_3N_4 was improved. The synergistic effect of the two can improve the photocatalytic performance of g-C_3N_4 more significantly than that of single MoS_2 and GO.The degradation rate of Rhb in 80 / 20MG sample is g-C3Ns 40.3MN and 0.3%NG under visible light, respectively. 2.9-fold, 1.7-fold and 1.6-fold.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;TQ136.12

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