一种简单前驱体预处理策略制备多孔氮化碳和负载型多孔氮化碳及其高效可见光光催化活性（英文）

发布时间：2018-04-23 09:43

本文选题：多孔微观结构 + 石墨相氮化碳　；参考：《催化学报》2017年03期

【摘要】：作为一种非金属半导体光催化剂,石墨相氮化碳(g-C_3N_4)已广泛应用于水中有机污染物去除、劈裂水产氢、二氧化碳还原制碳氢化合物燃料以及选择性氧化有机合成等许多光催化领域.然而,聚集态层状结构和粉末物理状态严重限制了g-C_3N_4在非均相光催化反应中的实际应用.一方面,g-C_3N_4的聚集态层状结构限制了光生载流子的表面迁移并增加了光催化反应的传质阻力.另一方面,由于附加的固-液分离步骤,粉体g-C_3N_4不便于实际应用.因此,为解决g-C_3N_4的上述缺点,一些研究已经进行并集中于g-C_3N_4的形貌控制合成及负载.构建多孔微观结构是合成具有优异光催化活性g-C_3N_4的有效途径之一.本文研究表明,盐酸或乙二醇预处理的三聚氰胺均可用作制备多孔g-C_3N_4的前驱体.有趣的是,由于在多孔g-C_3N_4制备体系中不同制孔单元的共存,与通过盐酸或乙二醇单独预处理的三聚氰胺制备的多孔g-C_3N_4相比,通过二者共同预处理的三聚氰胺制备的多孔g-C_3N_4具有更丰富的多孔微观结构.与制备负载型二氧化钛不同,由于在制备g-C_3N_4过程中缺少溶胶-凝胶步骤,因此负载型g-C_3N_4较难制备.而且,对于氟-锡氧化物(FTO)基底负载的g-C_3N_4,在实际应用中存在一些不足.首先,FTO基底的片状物理结构不利于反应底物的扩散.其次,FTO基底的吸光效应会导致光能损失,因此g-C_3N_4只能在FTO基底的单面负载.最后,在g-C_3N_4和FTO基底之间无化学作用,因此在光催化反应过程中不可避免造成g-C_3N_4的损失.因此,以盐酸/乙二醇共同预处理的三聚氰胺作原料,氢氟酸/3-氨基丙基三甲氧基硅烷共同预处理的石英棒作基底,首次制备了多孔g-C_3N_4和负载型多孔g-C_3N_4.丰富的多孔微观结构使得所制多孔g-C_3N_4具有优异的光催化活性;且由于多孔g-C_3N_4与石英棒基底间存在化学作用,因而具有相当高的稳定性.另外,由于在构建石英棒反应器之后不影响光生载流子的表面迁移和目标有机污染物的扩散,因此负载型多孔g-C_3N_4的光催化活性与粉体多孔g-C_3N_4相似.所制备多孔g-C_3N_4和负载型多孔g-C_3N_4的光催化活性通过在可见光条件下单组份有机废水的处理进行初步评价.在有机污染物降解同时产氢系统中,由于水和有机污染物之间的氧化还原反应难于进行,因此与传统的光催化降解和产氢系统相比,所制多孔g-C_3N_4的氢气产率和降解效率均显著降低;然而,在有机污染物降解同时产氢系统中,随着该材料光催化活性的提高,氢气产率和降解效率同时提高.这是因为光催化剂电子传递能力的提高促进了有机污染物和水之间的氧化还原反应.
[Abstract]:As a non-metallic semiconductor photocatalyst, graphite-phase carbon nitride (GN) g-C _ 3N _ 4) has been widely used in the removal of organic pollutants in water and the splitting of aquatic hydrogen. Carbon dioxide reduction to hydrocarbon fuel and selective oxidation of organic synthesis and many other areas of photocatalysis. However, the practical application of g-C_3N_4 in heterogeneous photocatalytic reactions is severely limited by the hierarchical structure of aggregates and the physical state of powders. On the one hand, the agglomerated layered structure of C3NIV limits the surface migration of photogenerated carriers and increases the mass transfer resistance of photocatalytic reactions. On the other hand, due to the additional solid-liquid separation steps, powder g-C_3N_4 is not suitable for practical application. Therefore, in order to solve the above disadvantages of g-C_3N_4, some researches have been carried out and focused on the morphology control synthesis and loading of g-C_3N_4. Constructing porous microstructure is one of the effective ways to synthesize g-C_3N_4 with excellent photocatalytic activity. The results show that melamine pretreated with hydrochloric acid or ethylene glycol can be used as precursor for the preparation of porous g-C_3N_4. Interestingly, because of the coexistence of different pore making units in the porous g-C_3N_4 preparation system, compared with the porous g-C_3N_4 prepared by melamine prepared by hydrochloric acid or ethylene glycol alone, The porous g-C_3N_4 prepared by melamine pretreated by both has more porous microstructure. Different from the preparation of supported titanium dioxide, it is difficult to prepare supported g-C_3N_4 because of the lack of sol-gel step in the preparation of g-C_3N_4. Moreover, there are some shortcomings in the practical application of g-C _ 3N _ 4 for fluorine-tin oxide oxide (FTO) substrate. Firstly, the sheet physical structure of FTO substrate is not conducive to the diffusion of the substrate. Secondly, the absorption effect of FTO substrate will lead to the loss of light energy, so g-C_3N_4 can only be loaded on one side of FTO substrate. Finally, there is no chemical interaction between g-C_3N_4 and FTO substrate, so the loss of g-C_3N_4 is inevitable in the photocatalytic reaction. Therefore, porous g-C_3N_4 and supported porous g-C _ 3s _ 3N _ 4 were prepared by using melamine co-pretreated with hydrochloric acid / ethylene glycol as raw material and quartz rod pretreated with hydrofluoric acid / 3-aminopropyltrimethoxysilane as substrate for the first time. The porous g-C_3N_4 has excellent photocatalytic activity due to its rich porous microstructure and has high stability due to the chemical interaction between porous g-C_3N_4 and quartz rod substrate. In addition, the photocatalytic activity of supported porous g-C_3N_4 is similar to that of porous g-C_3N_4 because the surface migration of photogenerated carriers and the diffusion of target organic pollutants are not affected after the construction of quartz rod reactor. The photocatalytic activity of porous g-C_3N_4 and supported porous g-C_3N_4 was preliminarily evaluated by the treatment of one-component organic wastewater under visible light. In the organic pollutant degradation and hydrogen production system, the redox reaction between water and organic pollutants is difficult, so compared with the traditional photocatalytic degradation and hydrogen production system, The hydrogen yield and degradation efficiency of porous g-C_3N_4 decreased significantly, but in the system of organic pollutant degradation and hydrogen production, the hydrogen yield and degradation efficiency increased with the increase of photocatalytic activity. This is because the improved electron transport capacity of photocatalysts promotes the redox reaction between organic pollutants and water.
【作者单位】：南昌航空大学江西省持久性污染物控制与资源循环利用重点实验室;
【基金】：supported by the National Natural Science Foundation of China(51568049,51208248,51468043,21366024) the National Science Fund for Excellent Young Scholars(51422807) the Natural Science Foundation of Jiangxi Province,China(20161BAB206118,20114BAB213015) the Natural Science Foundation of Jiangxi Provincial Department of Education,China(GJJ14515,GJJ12456)~~
【分类号】：O643.36

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