應用氮摻雜碳量子點與氫氧化錫酸鋅/二氧化錫二元複合物於光催化技術去除氮氧化物之研究

Study of Photocatalytic Removal of Nitrogen Oxides by using Nitrogen-Doped Carbon Quantum Dots and Zinc Hydroxide Stannate/SnO2 Binary Complexes

陳余育(Yu-Yu Chen)

指導教授 ： 游勝傑 ； 王雅玢

中原大學/工學院/環境工程學系/碩士(2018年)

https://doi.org/10.6840/cycu201800383

摘要

氮氧化物的來源主要分為自然界及人為因素。自然界形成氮氧化物主要是來自於雷電、火災及微生物的固氮作用；人為活動主要係以燃燒行為所排放，而燃燒過程則來自於固定污染源(如發電廠、焚化爐等)及移動污染源(如汽機車)。氮氧化物不僅會造成人體的危害，可能會引起支氣管炎、肺氣腫，還會造成光化學煙霧、酸雨之形成及臭氧層破壞等環境危害。為了解決氮氧化物污染問題，本研究利用光催化技術，進行氮氧化物之降解，然而大多數半導體光催化劑存在著只能被紫外光激發，且易產生光生載流子容易複合等問題。
本研究利用簡單、低成本之水熱法製備出氮摻雜碳量子點(N-CQDs)，以檸檬酸及尿素作為碳源，再使用溶劑熱法，以SnCl4∙5H2O及C4H10O6Zn作為金屬源，成功合成出N-CQDs/ZnSn(OH)6/SnO2複合光催化劑，利用簡單且無二次污染之光催化反應，來降解氮氧化物，並進一步利用XRD、DRS、FTIR、ESR等儀器來進行特徵分析。實驗以不同pH值之前驅液及N-CQDs添加量之不同，於NO 400ppb之濃度下進行光催化降解實驗測試，以找尋最佳合成材料及實驗參數，並嘗試推論N-CQDs/ZnSn(OH)6/SnO2光催化劑對降解NO之反應機制。
實驗結果顯示，ZnSn(OH)6前驅液之pH會影響產物是否含有SnO2，且於400ppb之NO光催化降解實驗中，在可見光下，ZnSn(OH)6有無存在SnO2及引入N-CQDs之條件下，N-CQDs/ZnSn(OH)6/SnO2有36.6%之活性大於N-CQDs/ZnSn(OH)6之16.8%之活性；且在調整N-CQDs之添加量，以N-CQDs/ZnSn(OH)6/SnO2-600在可見光下具有最佳降解效果，達到35.5%之降解率及149.13ppb之去除量，且二氧化氮生成量幾乎為0ppb，這可以說明此催化劑不會產生二次污染物—二氧化氮是一個對環境友善之材料。N-CQDs之引入使其光觸媒可以利用可見光直接降解污染物，並在分解污染物過程中不易失活，且因為SnO2與ZnSn(OH)6之協同作用，使N-CQDs/ZnSn(OH)6/SnO2複合材料之催化活性為四種條件下最佳。

關鍵字

氫氧化錫酸鋅 ； 氮摻雜碳量子點 ； 二氧化錫 ； 光催化 ； 氮氧化物

並列摘要

Source of Nitrogin Oxide mainly divided into nature and hunam factors. The formation of nitrogan oxides in nature is mainly caused by lighting, fire and microbial nitrogen fixation. Human activities are mainly emitted by combusion behavior, while the combustion process comes from stationary pollution sources (such as power plants, incinerators ,etc.) and mobile pollution sources (such as steam locomotive). Nitrogen oxides not only cause harm to the human body, but also may cause bronchitis, emphysema, and environmental hazards such as photochemical smog, acid rain, and ozone layer damage. In order to solve the problem of nitrogen oxide pollution, this study uses photocatalytic technology to degrade nitrogen oxides. However, most semiconductor photocatalysts can only be excited by ultraviolet light, and it is easy to produce photo-generated carriers that are easy to recombine.
In this study, N-CQDs were prepared by simple and low-cost hydrothermal method with citric acid and urea as carbon sources, and then N-CQDs/ZnSn(OH)6/SnO2 was successfully synthesized by using solvothermal method with SnCl4∙5H2O and C4H10O6Zn as metal sources. The composite photocatalyst utilizes a simple and non-primary photocatalytic reaction to degrade nitrogan oxides, and further utilizes XRD, DRS, FTIR, ESR and other instruments for feature analysis. Using different pH of precursor solution and different additions of N-CQDs to find the best synthetic materials and experimental parameters in experiment of removal NO at 400 ppb. Then discussed the reaction principle of N-CQDs/ ZnSn(OH)6/SnO2 photocatalyst on NO degrade.
The experimental results show that the pH of the ZnSn(OH)6 precursor affects whether the product contains SnO2, and in the 400 ppb NO photocatalytic degradation experiment, the presence or absence of SnO2 is observed in the visible light of ZnSn(OH)6. Under the conditions of introducing N-CQDs, 36.6% of the activity of N-CQDs/ZnSn(OH)6/SnO2 is greater than 16.8% of the activity of N-CQDs/ZnSn(OH)6; and the amount of N-CQDs added is adjusted. N-CQDs/ZnSn(OH)6/SnO2-600 has the best degradation effect under visible light, achieving a degradation rate of 35.5% and a removal of 149.13 ppb, and the production of nitrogen dioxide was almost 0 ppb.This suggests that the catalyst does not produce secondary contaminants - nitrogen dioxide. It is an environmentally friendly material. The introduction of N-CQDs enables its photocatalyst to directly degrade pollutants by visible light and is not easily deactivated during the decomposition of pollutants. Because of the synergistic action of SnO2 and ZnSn(OH)6, the catalytic activity of N-CQDs/ZnSn(OH)6/SnO2 composite is optimal under four conditions.

並列關鍵字

N-CQDs ； ZnSn(OH)6 ； SnO2 ； Photocatalytic ； Nitrogen oxides

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