几种金属氧化物基复合光催化剂的制备及其可见光催化性能研究
发布时间：2018-11-26 21:22
【摘要】：氧化钨(WO_3)是一种传统的金属氧化物,具有氧化性强、无二次污染、能耗低、易制备和可重复利用等优点,在光催化降解有机污染物领域拥有广阔的应用前景。然而,由于WO_3存在光生电子-空穴对复合率高、光催化反应中量子效率低等缺陷严重制约了其实际应用。钙钛矿型结构金属氧化物由于其独特的层状结构、化学性质稳定和制备成本低等优点,在光催化制氢和降解有机污染物领域受到广泛的关注,但该类材料只能响应紫外光,太阳能的利用率较低。为了弥补上述金属氧化物材料的不足,研发新型、稳定、高效的可见光相应的光催化材料,本论文以金属氧化物为主体,负载不同的载体,得到增强可见光响应的复合光催化材料。通过多种表征手段分析了所制备催化剂的微观结构、光电性质和光催化性能,并进一步探讨了其光催化机理。具体研究内容如下:1.通过简单的沉淀法成功制备了系列AgI/WO_3无媒介直接Z型纳米异质结复合光催化剂,对所制备AgI/WO_3样品进行了XRD、XPS和TEM等表征,结果表明,所制备的AgI/WO_3无媒介直接Z型异质结提高了光生电荷的分离效率。可见光条件下降解盐酸四环素(TC)的结果显示,20%AgI/WO_3的降解效率在60 min内达到75%,且稳定性较高。对光催化机理的探讨发现,AgI/WO_3在光降解过程中产生的h+和·O2-是反应中的活性物质。2.通过简单的水热法将剥片得到的K~+CNb_3O_(10)~-与g-C_3N_4纳米片复合,成功制备了2D-2D g-C_3N_4/K~+CNb_3O_(10)~-纳米异质结复合光催化剂。通过XRD、FT-IR、XPS、BET和TEM等表征对所制备的样品进行了分析,结果表明,K~+CNb_3O_(10)~-与g-C_3N_4之间存在较强的界面作用。光催化实验结果表明,g-C_3N_4纳米片的引入,有效地增强了g-C_3N_4/K~+CNb_3O_(10)~-的可见光响应能力。20%g-C_3N_4/K~+CNb_3O_(10)~-样品在90 min内降解TC的效率达81%,且经4次循环使用后依然保持较高的活性。通过对光催化降解TC的中间产物的分析,探究了g-C_3N_4/K~+CNb_3O_(10)~-光降解TC的过程。光催化机理研究显示,g-C_3N_4/K~+CNb_3O_(10)~-纳米异质结复合光催化剂降解TC的过程中产生的·O2-和h+对反应起主要作用。3.通过水热法将K~+CNb_3O_(10)~-与石墨烯(GO)复合制备GO/K~+CNb_3O_(10)~-复合光催化剂,并对其进行了XRD、Raman、XPS、AFM和TEM等表征,结果表明,GO与K~+CNb_3O_(10)~-成功复合并形成较强的协同作用。光降解实验、PL分析和光电测试的结果表明,GO与K~+CNb_3O_(10)~-的成功复合,有效增强了该催化剂的可见光响应能力。在光催化降解TC实验中,2%GO/KCNO的光降解效率展现出较高的光催化性能,其150 min内其降解TC效率可达81.6%。光催化机理的探讨中发现,GO的敏化作用拓展了复合光催化剂的光响应范围;该复合光催化剂在降解TC的过程中产生的唯一活性物质是·O_2~-。
[Abstract]:Tungsten oxide (WO_3) is a kind of traditional metal oxide, which has the advantages of strong oxidation, no secondary pollution, low energy consumption, easy preparation and reusability. It has a broad application prospect in the field of photocatalytic degradation of organic pollutants. However, due to the high photoelectron / hole pair recombination rate of WO_3 and the low quantum efficiency in photocatalytic reaction, its practical application is seriously restricted. Perovskite-type metal oxides have attracted extensive attention in the field of photocatalytic hydrogen production and degradation of organic pollutants due to their unique layered structure, stable chemical properties and low preparation cost. However, these materials can only respond to ultraviolet light. The utilization rate of solar energy is low. In order to make up for the shortcomings of the above metal oxide materials and to develop new, stable and efficient photocatalytic materials for visible light, this paper takes metal oxides as the main body and supports different carriers. A composite photocatalytic material with enhanced visible light response was obtained. The microstructure, photoelectric properties and photocatalytic properties of the prepared catalysts were analyzed by various characterization methods, and the photocatalytic mechanism was further discussed. The specific research contents are as follows: 1. A series of AgI/WO_3 direct Z-type nanocrystalline heterojunction photocatalysts were successfully prepared by simple precipitation method. The AgI/WO_3 samples were characterized by XRD,XPS and TEM. The preparation of AgI/WO_3 without direct Z heterojunction improves the efficiency of photocharge separation. The results of degradation of tetracycline hydrochloride (TC) under visible light condition showed that the degradation efficiency of 20%AgI/WO_3 reached 75% within 60 min and the stability was high. It is found that h and O _ 2- produced in photodegradation of AgI/WO_3 are active substances in the reaction. The photocatalyst of 2D-2D g-C _ 3N _ 3N _ 3N _ 3N _ (4 / K ~ CNb_3O_ (10) ~ -) nanoheterojunction composite photocatalyst was successfully prepared by the simple hydrothermal method of lamination of K ~ CNb_3O_ (10) ~-with g-C_3N_4 nanoparticles. The samples were characterized by XRD,FT-IR,XPS,BET and TEM. The results show that there exists strong interfacial interaction between K ~ CNb_3O_ (10) ~-and g-C_3N_4. The photocatalytic experiment results show that the introduction of g-C_3N_4 nanoparticles, It effectively enhanced the visible light response of g-C3Ns 4 / K ~ CNb_3O_ (10) ~ -. 20 g-C _ 3N _ 3N _ (4) / K ~ (10) ~-samples were able to degrade TC in 90 min. And after 4 times of recycling, the activity is still high. By analyzing the intermediate products of photocatalytic degradation of TC, the process of photodegradation of TC by g-C _ s _ 3N _ 3N _ (4 / K ~ CNb_3O_ (10) ~ -) was investigated. The photocatalytic mechanism of g-C3N4 / K- CNb_3O_ (10) -nanoheterojunction composite photocatalyst for TC degradation shows that the O _ 2- and h produced by g-C _ 3N _ 4 / K ~-heterojunction composite photocatalyst play a major role in the reaction. GO/K~ CNb_3O_ (10) ~-photocatalyst was prepared by hydrothermal method, and characterized by XRD,Raman,XPS,AFM and TEM. GO was successfully combined with K ~ CNb_3O_ (10) ~-to form a strong synergistic effect. The results of photodegradation experiment, PL analysis and photoelectricity test show that the combination of GO and K ~ CNb_3O_ (10) ~-can effectively enhance the visible light response ability of the catalyst. In the experiment of photocatalytic degradation of TC, the photodegradation efficiency of 2%GO/KCNO showed high photocatalytic performance, and the degradation efficiency of TC in 150 min could reach 81.6%. In the study of photocatalytic mechanism, it is found that the sensitization of GO extends the photoresponse range of the composite photocatalyst, and the only active substance produced by the composite photocatalyst during the degradation of TC is O _ 2O _ 2 ~ (-).
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36
本文编号：2359656
[Abstract]:Tungsten oxide (WO_3) is a kind of traditional metal oxide, which has the advantages of strong oxidation, no secondary pollution, low energy consumption, easy preparation and reusability. It has a broad application prospect in the field of photocatalytic degradation of organic pollutants. However, due to the high photoelectron / hole pair recombination rate of WO_3 and the low quantum efficiency in photocatalytic reaction, its practical application is seriously restricted. Perovskite-type metal oxides have attracted extensive attention in the field of photocatalytic hydrogen production and degradation of organic pollutants due to their unique layered structure, stable chemical properties and low preparation cost. However, these materials can only respond to ultraviolet light. The utilization rate of solar energy is low. In order to make up for the shortcomings of the above metal oxide materials and to develop new, stable and efficient photocatalytic materials for visible light, this paper takes metal oxides as the main body and supports different carriers. A composite photocatalytic material with enhanced visible light response was obtained. The microstructure, photoelectric properties and photocatalytic properties of the prepared catalysts were analyzed by various characterization methods, and the photocatalytic mechanism was further discussed. The specific research contents are as follows: 1. A series of AgI/WO_3 direct Z-type nanocrystalline heterojunction photocatalysts were successfully prepared by simple precipitation method. The AgI/WO_3 samples were characterized by XRD,XPS and TEM. The preparation of AgI/WO_3 without direct Z heterojunction improves the efficiency of photocharge separation. The results of degradation of tetracycline hydrochloride (TC) under visible light condition showed that the degradation efficiency of 20%AgI/WO_3 reached 75% within 60 min and the stability was high. It is found that h and O _ 2- produced in photodegradation of AgI/WO_3 are active substances in the reaction. The photocatalyst of 2D-2D g-C _ 3N _ 3N _ 3N _ 3N _ (4 / K ~ CNb_3O_ (10) ~ -) nanoheterojunction composite photocatalyst was successfully prepared by the simple hydrothermal method of lamination of K ~ CNb_3O_ (10) ~-with g-C_3N_4 nanoparticles. The samples were characterized by XRD,FT-IR,XPS,BET and TEM. The results show that there exists strong interfacial interaction between K ~ CNb_3O_ (10) ~-and g-C_3N_4. The photocatalytic experiment results show that the introduction of g-C_3N_4 nanoparticles, It effectively enhanced the visible light response of g-C3Ns 4 / K ~ CNb_3O_ (10) ~ -. 20 g-C _ 3N _ 3N _ (4) / K ~ (10) ~-samples were able to degrade TC in 90 min. And after 4 times of recycling, the activity is still high. By analyzing the intermediate products of photocatalytic degradation of TC, the process of photodegradation of TC by g-C _ s _ 3N _ 3N _ (4 / K ~ CNb_3O_ (10) ~ -) was investigated. The photocatalytic mechanism of g-C3N4 / K- CNb_3O_ (10) -nanoheterojunction composite photocatalyst for TC degradation shows that the O _ 2- and h produced by g-C _ 3N _ 4 / K ~-heterojunction composite photocatalyst play a major role in the reaction. GO/K~ CNb_3O_ (10) ~-photocatalyst was prepared by hydrothermal method, and characterized by XRD,Raman,XPS,AFM and TEM. GO was successfully combined with K ~ CNb_3O_ (10) ~-to form a strong synergistic effect. The results of photodegradation experiment, PL analysis and photoelectricity test show that the combination of GO and K ~ CNb_3O_ (10) ~-can effectively enhance the visible light response ability of the catalyst. In the experiment of photocatalytic degradation of TC, the photodegradation efficiency of 2%GO/KCNO showed high photocatalytic performance, and the degradation efficiency of TC in 150 min could reach 81.6%. In the study of photocatalytic mechanism, it is found that the sensitization of GO extends the photoresponse range of the composite photocatalyst, and the only active substance produced by the composite photocatalyst during the degradation of TC is O _ 2O _ 2 ~ (-).
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36
【参考文献】
相关期刊论文 前2条
1 张金水;王博;王心晨;;氮化碳聚合物半导体光催化[J];化学进展;2014年01期
2 ;Photocatalytic degradation of rhodamine B by dye-sensitized TiO_2 under visible-light irradiation[J];Science China(Chemistry);2011年01期
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