具有异质结结构或主导晶面的光催化剂的制备和性能研究

发布时间：2018-04-15 22:18

本文选题：光催化 + 异质结　；参考：《福建师范大学》2016年硕士论文

【摘要】：目前,全球能源短缺以及环境污染等问题已经成为世界性的棘手问题。半导体光催化剂已经引起人们的广泛关注,并且将其视为解决当前能源和环境问题行之有效的方法。例如,半导体Ti02具有较高的光催化活性,可以氧化降解有机污染物,然而由于Ti02较低的太阳能利用率以及较慢的反应速率等问题阻碍了其进一步的应用。因此,寻找新型的、光响应范围宽的、太阳能利用率高的、光催化活性高的光催化剂,成为目前光催化研究的新挑战。本文重点研究了具有异质结结构和主导晶面的光催化剂的制备、光催化性能及其光催化活性改善的机制。采用多种测试技术对所制备的催化剂的结构、形貌、物相组成、表面结构和比表面积等进行表征。并以罗丹明B为目标降解物,研究所合成的催化剂的光催化性能,探讨了催化剂的结构和组成对其光催化活性的影响。具体工作如下：通过水热合成法成功的制备了不同复合比的ZnS/ZnWO4异质结光催化剂,并且将ZnS、ZnWO4与异质结ZnS/ZnWO4的光催化活性进行了对比。实验结果表明,当异质结ZnS/ZnWO4的复合摩尔比为0.83时其光催化活性最高,在90min内RhB基本被降解完全。研究发现ZnS/ZnWO4异质结光催化剂光催化活性的显著提高是因为半导体ZnS与ZnWO4构成交错型非p-n型异质结,该类型的异质结能有效的将光生电子-空穴对进行分离。通过煅烧以及水热合成法成功制备了具有带隙可调的C3N4/Zn1-xCdxS(0≤x≤1)异质结光催化剂。并且以RhB为目标降解对象,研究了复合前后的g-C3N4、 Zn1-xCdxS(0≤x≤1以及异质结C3N4/Zn1-xCdxS (0≤x≤1)的光催化活性。实验结果表明0.10 C3N4/Zn0.8Cd0.2S的光催化活性最高,在90 min内可以将RhB降解97.9%。g-C3N4与Zn1-xCdxS(0≤x≤1)复合形成S-C型异质结C3N4/Zn1-xCdxS (0≤x≤1)之后,禁带宽度变窄、光响应范围增大。另外,研究发现异质结0.10C3N4/Zn0.8Cd0.2S降解RhB过程中的主要活性物种是超氧自由基(02·-)和价带空穴(h+)；在可见光照射下降解RhB的重复实验中,异质结0.10 C3N4/Zn0.8Cd0.2S表现出较高的光稳定性,具备潜在的应用价值。通过化学沉淀法和水热合成法,成功制备出纯CdWO4、BiOBr以及不同摩尔比的p-n型异质结CdWO4/BiOBr。并且以RhB为目标降解对象,研究了复合前后的CdWO4、BiOBr以及p-n型异质结CdWO4/BiOBr的光催化活性。实验结果表明p-n型异质结15%CdWO4/BiOBr的光催化活性最高,在8 min内可以将RhB降解完全。另外,还发现p-n型异质结15%CdWO4/BiOBr降解RhB过程中的主要活性物种是超氧自由基(02·-)和价带空穴(h+)。在不同温度下,通过沉淀法和水热合成法成功制备了具有较高光催化活性的可见光催化剂Ag3PO4微晶。并且将不同温度条件下,通过不同方法合成的Ag3PO4微晶的光催化活性进行了对比。实验结果表明,120℃条件下水热合成的Ag3PO4样品表现出最高的光催化活性(可见光照射下,6 min内RhB降解了97.83%)。另外,还发现120℃条件下水热合成的Ag3PO4样品降解RhB过程中的主要活性物种是价带空穴(h+)和羟基自由基(·OH),而且该羟基自由基(·OH)是由价带空穴(h+)产生。此外,120℃条件下水热合成的Ag3PO4微晶中的主导晶面为(110)晶面,它能够有效地将光生电子-空穴对分离,进而提高光催化活性。
[Abstract]:At present, the global energy shortage and environmental pollution has become a difficult problem in the world. The Semiconductor Photocatalysts have attracted wide attention, and will be regarded as effective methods to solve the problem of energy and environment. For example, Ti02 has a higher photocatalytic activity of semiconductor, can oxidative degradation of organic pollutants, but due to the problem of Ti02 the low utilization rate of solar energy and the reaction rate slower hinder its further application. Therefore, the search for new, light response range, high utilization rate of solar energy, a photocatalyst with high activity, has become a new challenge in photocatalytic research. This paper focuses on the research with heterojunction structure and leading surface preparation of photocatalyst, the mechanism of improving the photocatalytic performance and photocatalytic activity. Using a variety of testing technology structure of the prepared catalyst, The morphology, phase composition, surface structure and surface area were characterized. And by using rhodamine B as target degradation, photocatalytic property was synthesized, the effects of catalyst composition and structure of influence on the photocatalytic activity. The specific work is as follows: through the hydrothermal synthesis method was successfully prepared with ZnS/ZnWO4 different than the node heterogeneity composite photocatalyst, and ZnS, were compared with the photocatalytic activity of ZnWO4 heterojunction ZnS/ZnWO4. Experimental results show that the highest photocatalytic activity when the molar ratio of compound heterojunction at 0.83 ZnS/ZnWO4 in 90min RhB was completely degraded. Basic research found that increased ZnS/ZnWO4 heterojunction photocatalysts the photocatalytic activity of ZnS and ZnWO4 semiconductor is because the interleaved type non p-n heterojunction, the heterogeneous type node can effectively transform the photogenerated electron hole pairs are separated by calcination and water. Hydrothermal synthesis was successfully prepared with tunable band gap of C3N4/Zn1-xCdxS (x = 0 ~ 1) heterojunction photocatalyst. And using RhB as the target object of degradation of composite before and after g-C3N4, Zn1-xCdxS (x = 0 ~ 1 and the heterojunction C3N4/Zn1-xCdxS (x = 0 ~ 1) the photocatalytic activity experiments. The results showed that the photocatalytic activity of C3N4/Zn0.8Cd0.2S 0.10 is the highest, in 90 min can degrade RhB 97.9%.g-C3N4 and Zn1-xCdxS (x = 0 ~ 1) composite forming type S-C heterojunction C3N4/Zn1-xCdxS (x = 0 ~ 1), the band gap, light response range increased. In addition, the study found that the main active species heterojunction 0.10C3N4/Zn0.8Cd0.2S degradation in the process of RhB is superoxide radical (02 -) and the hole (h+); under visible light irradiation experiments were repeated RhB degradation in the heterojunction 0.10 C3N4/Zn0.8Cd0.2S exhibited high light stability, has the potential application value through. The chemical precipitation method and hydrothermal synthesis method successfully prepared pure CdWO4, BiOBr and different mole ratio of type p-n heterojunction CdWO4/BiOBr. and degradation of composite objects in RhB, BiOBr and p-n before and after CdWO4, CdWO4/BiOBr type heterojunction photocatalytic activity. The experimental results show that the photocatalytic activity of p-n heterojunction 15%CdWO4/BiOBr the highest in 8 min RhB can be degraded completely. In addition, also found that the type p-n heterojunction main active species in the process of 15%CdWO4/BiOBr degradation of RhB is superoxide radical (02 -) and the hole (h+). At different temperatures by precipitation method and hydrothermal synthesis method successfully prepared with the higher photocatalytic activity of visible light catalyst Ag3PO4 microcrystals. And under different temperature conditions, the photocatalytic activity of Ag3PO4 synthesized by different methods were compared. The experimental results show that the temperature of 120 DEG C for hydrothermal synthesis The Ag3PO4 sample shows the highest photocatalytic activity (under visible light irradiation, the degradation of RhB 6 min 97.83%). In addition, they also found 120 DEG C under the condition of thermal degradation of RhB Ag3PO4 were the main active species in the process of synthesis is the holes in the valence band (h+) and hydroxyl radical (- OH), and the hydroxyl group free radical (- OH) is composed of holes in the valence band (h+). In addition, the condition of 120 DEG C hydrothermal synthesis of Ag3PO4 microcrystals in the dominant crystal surface (110) surface, it can effectively separate the photogenerated electron hole pairs, and then improve the photocatalytic activity.

【学位授予单位】：福建师范大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O643.36

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