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  • 學位論文

非金屬離子修飾石墨型氮化碳於光催化及量子點合成之應用

Photocatalysis and synthesis of quantum dots using non-metal ion doped graphitic carbon nitride

指導教授 : 陳志吉
共同指導教授 : 胡哲嘉(Che-Chia Wu)
本文將於2024/10/20開放下載。若您希望在開放下載時收到通知,可將文章加入收藏

摘要


不同的廢水處理方法中,光化學催化氧化法具備了低成本、節能、對環境友善等優點,近年來許多研究著重於製備不含金屬成分的光觸媒,除了對環境較更友好之外,也更能夠有效的減少金屬用量,並同時達到可調控光吸收之能力。因此,本研究以磷摻雜石墨型氮化碳以氧化還原進而分解有機汙染物,以達到去污染的效果。 本實驗透過熱縮合法,製備出含有兩個三嗪環及一個三唑環所組成石墨型氮化碳光觸媒(CNNS),為了提升石墨型氮化碳之光催化活性,將其摻雜不同比例的磷化物進行複合(xP-CNNS, x=1, 3, 6, 10 wt%)以填補或取代石墨型氮化碳之空缺,防止電子電洞對再結合,提升光觸媒性能。透過 BET 氮氣吸脫附確認其為第四型中孔材料。從XRD檢測結果顯示,經摻雜後的石墨型氮化碳在13度及27.4度仍有特徵峰出現,代表保持原先(100)和(002)晶格結構未受摻雜所影響;FTIR圖譜確認了石墨型氮化碳的主要結構與官能基並不會被磷摻雜所破壞;TEM形貌圖則確認P-CNNS為奈米薄片狀結構,且磷摻雜會使薄片形成孔洞;透過XPS分析,可得知石墨型氮化碳確實成功存有磷離子摻雜於其中,並取代了結構中的碳與碳空缺。接著透過紫外光可見光光譜與Mott-Schottky分析其光電化學特性,UV-Vis圖譜可看出材料可有效吸收可見光,經磷摻雜 有紅移的現象;而Mott-Schottky圖中則可得知CNNS與P-CNNS皆為n型半導體,且摻雜後的石墨型氮化碳之費米能階皆向負電位移動。 經磷摻雜後的光觸媒材料則應用於有機汙染物廢水羅丹明B (RhB)的移除,當以P-CNNS為光觸媒並在可見光燈源照射下,99.5 % RhB可於180分鐘的照射後被移除,其中又以6P-CNNS有最佳的光催化效果。因此,我們以6P-CNNS進行重複性實驗與單一波長照射光降解實驗,實驗結果則證實了本研究所製備之磷摻雜石墨型氮化碳為一種可有效吸收可見光的高穩定性光觸媒材料。 為了對廢水處理有更進一步的了解,我們將本實驗所製備出的石墨型氮化碳合成為量子點(CQDs),以檢測廢水中所含金屬汙染物濃度,並藉由摻雜氟離子(xF-CQDs, x=3, 6, 10 wt%)來提升量子點的光學性能,增加其光學靈敏度,透過PL光致發光檢測結果,可發現所製備出的量子點對汞離子及鐵離子均能產生明顯的螢光淬滅,而在LOD檢測下限計算的結果中,也能得出氟摻雜之量子點比未經摻雜之量子點能檢驗出含有較低濃度的金屬汙染物。

並列摘要


In order to enhance the photocatalysis activity, different weight percent Phosphorus ions doping in the graphite carbon nitride catalyst (xP-CNNS, x=1, 3, 6, 10 wt%) by thermal etching in this work. The Phosphorus ions of modified graphite carbon nitride can fill or replace the carbon ions from recombination of electron hole pairs in the catalyst structure. The XRD pattern ,TEM image and FT-IR spectra of P-CNNS confirmed that the morphologies and crystal structure of CNNS not affect by the Phosphorus ions doping. The XRD patterns indicated that the graphite carbon nitride after p doping still with two prominent peaks at approximately 13∘and 27.4∘, which corresponding to the (100) and (002) crystal planes. The FT-IR spectra confirmed that the p doping did not destroy the major structure and functional group of the catalyst. With the TEM images, the structure of catalyst was known as nanosheet like structure, and the nanosheet like structure appeared a lot of holes after p doping. The XPS analysis confirmed that the phosphorus ions were successfully doped into the graphite carbon nitride structure and replaced the carbon ions of the structure. The BET analysis results and the N2 adsorption-desorption isotherm curves showed that the catalyst is a Type IV mesoporous material. The sample CNNS and P-CNNS are confirmed as the n-type semiconductors due to the fermi level of the graphite carbon nitride after p doping all shift negative in the Mott-Schottky analysis. Then the P-doped photocatalysts were carried on to the photocatalysis for Rhodamine B (RhB) removal. The removal rate of p doped photocatalyst is 99.5% within 180 minutes irradiation, and the 6P-CNNS show the highest photodegradation efficiency among all photocatalyst. Therefore, we take 6P-CNNS to do the recycle test and photocatalytic under the monochromatic light, the results confirm that the 6P-CNNS is a highly stable visible light photocatalyst. At last, the graphite carbon nitride was synthesized to quantum dots (CQDs) to detect the concentration of metal ions pollutants in the wastewater. To improve the optical performance and optical sensitivity of quantum dots, the fluorine ions was doped into the quantum dots with different ration (xF-CQDs, x=3, 6, 10 wt%). Then check the fluorescence brightness with Photoluminescence. The results indicated that the modified quantum dots have obviously quenching to Mercury ions and Iron ions. And the results of limit of detection also confirm that the quantum dots have better optical sensitivity after F doping.

參考文獻


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