氧化锌和硫化锌基可见光催化材料的制备及其性能研究

发布时间：2018-06-29 04:35

  本文选题：钴 + 钼　； 参考：《南昌大学》2017年硕士论文

【摘要】：光催化作为一种有效的太阳能转化技术引起了研究者的广泛关注,多种新型的光催化材料被广泛研究并应用于光催化分解水制氢和有机污染物降解等领域。其中,ZnO和ZnS光催化材料在受到光激发后能快速产生光生电子和空穴,且它们导带的位置都比H+/H2的还原电势更负,当受到光辐射后可分解水制氢,但是,它们均属于宽禁带半导体材料,只能吸收太阳光中小于5%的紫外光,难以利用占主要光谱能量的可见光,极大地限制了其在光催化中的应用。因此,对ZnO和ZnS的表面结构、晶体结构和电子结构进行改性,使其具有可见光响应就显得尤为重要。本论文主要通过金属离子掺杂、形貌调控、构建异质结构等方法对其进行修饰改性,获得具有可见光响应的光催化材料。首先我们在水溶液中室温条件下,以锌粉为原料,氧化石墨烯(GO)为载体,利用Zn的强还原性和GO的强氧化性,通过氧化还原反应将锌粉负载在GO上,防止锌粉的团聚。通过钴(Co)离子的负载构建原电池,通过微电化学方法制备Co掺杂ZnO/rGO纳米颗粒。相对于ZnO/rGO,Co掺杂ZnO/rGO对400nm到700 nm的可见光区域有较好的吸收。在可见光(?≥420 nm)照射下,展现出了增强的光降解亚甲基蓝(MB)效率及光电流强度。其次,为了缩短光生载流子的迁移距离,减少光生电子空穴复合,以及改善ZnS的可见光催化活性,通过金属离子的引入调控ZnS的形貌结构并原位进行金属离子掺杂来提升光催化效率。本研究选用高价态的Mo离子对宽禁带半导体ZnS进行掺杂改性,采用一步水热法合成了钼(Mo)掺杂ZnS片。在生长过程中,Mo离子吸附在ZnS{111}晶面抑制该晶面方向的生长,得到{111}晶面占优的ZnS片状p型半导体材料。Mo掺杂ZnS片在整个可见光区域的吸收能力得到明显提升,并在可见光下具有更高的光电转化效率。最后,为了解决ZnO和ZnS只能吸收紫外光和光生电子空穴易复合的问题,并实现可见光催化制氢,发展了片状的ZnO并通过离子交换和光负载CdS纳米颗粒,合成了具有可见光吸收能力的ZnO/ZnS/CdS三元片状异质结构材料。在该异质结构中,CdS和ZnS以纳米颗粒形式嵌入ZnO片中并形成稳定的界面,有利于光生载流子的迁移。ZnO/ZnS/CdS三元片状异质结构在可见光下展现出更高的光催化产氢速率,进一步通过助催化剂Pt纳米颗粒的负载,使光催化制氢速率获得大幅提升。
[Abstract]:As an effective solar energy conversion technology, photocatalysis has attracted extensive attention of researchers. Many new photocatalytic materials have been widely studied and applied in the fields of photocatalytic decomposition of water for hydrogen production and degradation of organic pollutants. ZnO and ZnS photocatalytic materials can produce photogenerated electrons and holes quickly after photoexcitation, and their conduction band positions are more negative than the reduction potential of H / H _ 2. They can decompose water to produce hydrogen when exposed to light radiation, but, They all belong to wide band gap semiconductor materials. They can only absorb less than 5% ultraviolet light in the solar light. It is difficult to use the visible light which accounts for the main spectral energy, which greatly limits their application in photocatalysis. Therefore, it is very important to modify the surface structure, crystal structure and electronic structure of ZnO and ZnS to make them have visible light response. In this paper, metal ions doping, morphology control, and heterostructure construction were mainly used to modify the materials to obtain photocatalytic materials with visible light response. Firstly, zinc powder was loaded on go by redox reaction with zinc powder as raw material and graphene oxide (go) as carrier, and zinc powder was loaded on go by redox reaction to prevent the agglomeration of zinc powder. Co-doped ZnO / rGO nanoparticles were prepared by micro-electrochemical method. Compared with ZnO / rGOCO-doped ZnO / rgo, the visible region of 400nm to 700nm is well absorbed. Under visible light (? 鈮，

本文编号：2080870