因為獨特的物理、化學及光學性質，近年來石墨烯量子點材料逐漸受到注視。除了延續石墨烯原先具有的物化特性如: 大比表面積、化學物理穩定性、非毒性等之外，因為其奈米尺寸的大小，電子受到量子侷限效應與邊界效應而產生具有與半導體相似的性質，因此從原先零能隙衍生出具有可調控能隙的性質。近幾年來各界學者積極投入研究可調式能隙的石墨烯量子點，以理論與實驗方法探討量子點特性與影響能隙的因子，並將影響的因子主要歸納為粒子大小、表面官能基組成、邊緣結構與表面型態。
目前用以合成石墨烯量子點的方法多數以水熱法、溶熱法或濕式化學法合成，然而上述方法均涉及耗時、複雜的反應程序與化合物使用，將不利於工業化發展與後續應用。本研究提出一個簡易且快速的合成技術是利用大氣常壓微電漿系統製備石墨烯量子點，所使用的微電漿設備、製程程序與前驅物簡單，所合成的石墨烯量子點其平均粒徑為4.9 nm，為典型的藍光螢光性質，而量子螢光效率則約為1.5%。隨後透過改變製程物理參數如反應時間與前驅物濃度可得到不同光學特性之石墨烯量子點，研究結果顯示隨著反應時間增長或提高前驅物濃度都將增加石墨烯量子點的粒徑，且其螢光性質也產生紅位移，意味著石墨烯量子點能隙的減少是由於量子侷限效應所影響。在探討合成機制上，透過實行不同反應條件如改變氣體環境、前驅物與加入添加物等，從中推測在電漿環境中具有自由基聚合的反應程序，微電漿系統提供一個可初始化自由基聚合的環境與條件，使得前驅物分子在液面下可以自由基化並隨後聚合形成石墨烯量子點。
此外，本研究亦探討使用其他不同鏈長分子作為前驅物，經由大氣常壓微電漿處理後，其粒徑大小隨著使用的鏈長增加而變大，在螢光性質上同樣產生紅位移，進一步闡述量子侷限效應對其光學與物理性質的影響，這將有助於可調式螢光性質石墨烯量子點的發展與研究，並將可應用於特定技術或生醫領域上。

Graphene quantum dots (GQDs) have attracted attention due to its unique and superior physical, chemical and optical properties. On the basis of graphene structure, it possess large specific surface area, physiochemical stability and non-toxic. Electrons in GQDs would be limited by structure because of their nanoscale size. Hence, band gap opening of GQDs should be highly size-dependent, which is called quantum confinement. For this reason, GQDs have similar property which is non-zero band gap to semiconductor. In recent years, continuously increasing researches interest in tunable fluorescence GQDs. They probably categorize the effect factors of band gap into particle size, functional groups, edges structure and surface state.
Currently, most synthesis methods are using hydrothermal, solvothermal and wet chemistry. All of which are time-consuming, complex reaction procedure and chemicals unfavorable to its development and applications. Here, we presented a facile and rapid method to synthesize GQDs by atmospheric-pressure microplasma. The average diameter of as-product GQDs were 4.9 nm. They were typical blue fluorescence with quantum yield around 1.5%. Subsequently, through changing physical parameters like reaction time and precursor concentration, we can get different optical properties GQDs. PL emission wavelength were red shift, which suggested that band gap were decreased when the reaction time or precursor concentration were increased. Based on TEM and XPS analysis, their particles size had increasing tendency with analogous surface compositions, suggesting that PL red shift reason was originated from quantum confinement effect predominantly. The influence of using microplasma towards GQDs formation was also investigated. Through a series of experiments and paper review, we considered that radical polymerization were existed in solution. Microplasma can be as a radical initiator and induce precursor radicalized. Radicalized molecule subsequently were cyclized and finally polymerized to form GQDs.
Additionally, we also studied using different chain length molecule as precursor to implement microplasma. The characteristic analysis results exhibited a consistent of surface composition of as-product by XPS. GQDs particle size and PL emission wavelength were increased with using longer chain molecule. It meant that GQDs band gap were decreased. These results further prove quantum confinement effect and chemical formula effect on GQDs physical and optical properties. This study will contribute to the development of tunable fluorescence GQDs and be applied in specific fields or biomedical techniques.

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