幾種金屬氧化物基復(fù)合光催化劑的制備及其可見光催化性能研究
發(fā)布時(shí)間：2018-11-26 21:22
【摘要】：氧化鎢(WO_3)是一種傳統(tǒng)的金屬氧化物,具有氧化性強(qiáng)、無二次污染、能耗低、易制備和可重復(fù)利用等優(yōu)點(diǎn),在光催化降解有機(jī)污染物領(lǐng)域擁有廣闊的應(yīng)用前景。然而,由于WO_3存在光生電子-空穴對復(fù)合率高、光催化反應(yīng)中量子效率低等缺陷嚴(yán)重制約了其實(shí)際應(yīng)用。鈣鈦礦型結(jié)構(gòu)金屬氧化物由于其獨(dú)特的層狀結(jié)構(gòu)、化學(xué)性質(zhì)穩(wěn)定和制備成本低等優(yōu)點(diǎn),在光催化制氫和降解有機(jī)污染物領(lǐng)域受到廣泛的關(guān)注,但該類材料只能響應(yīng)紫外光,太陽能的利用率較低。為了彌補(bǔ)上述金屬氧化物材料的不足,研發(fā)新型、穩(wěn)定、高效的可見光相應(yīng)的光催化材料,本論文以金屬氧化物為主體,負(fù)載不同的載體,得到增強(qiáng)可見光響應(yīng)的復(fù)合光催化材料。通過多種表征手段分析了所制備催化劑的微觀結(jié)構(gòu)、光電性質(zhì)和光催化性能,并進(jìn)一步探討了其光催化機(jī)理。具體研究內(nèi)容如下:1.通過簡單的沉淀法成功制備了系列AgI/WO_3無媒介直接Z型納米異質(zhì)結(jié)復(fù)合光催化劑,對所制備AgI/WO_3樣品進(jìn)行了XRD、XPS和TEM等表征,結(jié)果表明,所制備的AgI/WO_3無媒介直接Z型異質(zhì)結(jié)提高了光生電荷的分離效率。可見光條件下降解鹽酸四環(huán)素(TC)的結(jié)果顯示,20%AgI/WO_3的降解效率在60 min內(nèi)達(dá)到75%,且穩(wěn)定性較高。對光催化機(jī)理的探討發(fā)現(xiàn),AgI/WO_3在光降解過程中產(chǎn)生的h+和·O2-是反應(yīng)中的活性物質(zhì)。2.通過簡單的水熱法將剝片得到的K~+CNb_3O_(10)~-與g-C_3N_4納米片復(fù)合,成功制備了2D-2D g-C_3N_4/K~+CNb_3O_(10)~-納米異質(zhì)結(jié)復(fù)合光催化劑。通過XRD、FT-IR、XPS、BET和TEM等表征對所制備的樣品進(jìn)行了分析,結(jié)果表明,K~+CNb_3O_(10)~-與g-C_3N_4之間存在較強(qiáng)的界面作用。光催化實(shí)驗(yàn)結(jié)果表明,g-C_3N_4納米片的引入,有效地增強(qiáng)了g-C_3N_4/K~+CNb_3O_(10)~-的可見光響應(yīng)能力。20%g-C_3N_4/K~+CNb_3O_(10)~-樣品在90 min內(nèi)降解TC的效率達(dá)81%,且經(jīng)4次循環(huán)使用后依然保持較高的活性。通過對光催化降解TC的中間產(chǎn)物的分析,探究了g-C_3N_4/K~+CNb_3O_(10)~-光降解TC的過程。光催化機(jī)理研究顯示,g-C_3N_4/K~+CNb_3O_(10)~-納米異質(zhì)結(jié)復(fù)合光催化劑降解TC的過程中產(chǎn)生的·O2-和h+對反應(yīng)起主要作用。3.通過水熱法將K~+CNb_3O_(10)~-與石墨烯(GO)復(fù)合制備GO/K~+CNb_3O_(10)~-復(fù)合光催化劑,并對其進(jìn)行了XRD、Raman、XPS、AFM和TEM等表征,結(jié)果表明,GO與K~+CNb_3O_(10)~-成功復(fù)合并形成較強(qiáng)的協(xié)同作用。光降解實(shí)驗(yàn)、PL分析和光電測試的結(jié)果表明,GO與K~+CNb_3O_(10)~-的成功復(fù)合,有效增強(qiáng)了該催化劑的可見光響應(yīng)能力。在光催化降解TC實(shí)驗(yàn)中,2%GO/KCNO的光降解效率展現(xiàn)出較高的光催化性能,其150 min內(nèi)其降解TC效率可達(dá)81.6%。光催化機(jī)理的探討中發(fā)現(xiàn),GO的敏化作用拓展了復(fù)合光催化劑的光響應(yīng)范圍;該復(fù)合光催化劑在降解TC的過程中產(chǎn)生的唯一活性物質(zhì)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 ~ (-).
【學(xué)位授予單位】：江蘇大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O643.36
本文編號：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 ~ (-).
【學(xué)位授予單位】：江蘇大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O643.36
【參考文獻(xiàn)】
相關(guān)期刊論文 前2條
1 張金水;王博;王心晨;;氮化碳聚合物半導(dǎo)體光催化[J];化學(xué)進(jìn)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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