【摘要】：石墨烯量子點(Graphene Quantum Dots,GQDs)具有顯著的量子限域效應、邊界效應和良好的生物兼容性等特點,在熒光標記、微納傳感器、靶向醫(yī)療、生物示蹤及電催化領域具有巨大的應用前景。摻雜能有效地調節(jié)石墨烯量子點的晶體和電子結構,從而改變其光致發(fā)光和電催化等性能。目前石墨烯量子點的產業(yè)化應用仍然存在諸多難題,如可控制備、改性和低成本量產等。本文以碳纖維和石墨粉為原料,采用強氧化刻蝕割裂法制備石墨烯量子點,并提出一種能顯著提高石墨烯基材料摻雜量的通用制備方法—階躍分步摻雜法。成功制備出摻雜型石墨烯量子點及其納米復合物,應用于光致發(fā)光和電催化。本文主要開展以下工作:1、石墨烯量子點的可控制備。分別以碳纖維(Carbon Fibers)和石墨粉(Graphite Powders)為原材料,采用強氧化刻蝕割裂法制備石墨烯量子點。實驗結果顯示,兩種石墨烯量子點的粒徑均在6 nm以下,熒光量子產率分別為2%、1%(硫酸奎寧為參比),表現(xiàn)出顯著的熒光依賴激發(fā)波長變化的性質。2、石墨烯量子點的摻雜。先制備氟摻雜石墨烯量子點F-GQDs(Fluorine-doped GQDs),使GQDs內部缺陷濃度增加,再進行氨氣高溫摻氮處理制備氮原子比例可控的N-GQDs。實驗結果顯示,當氟化劑與石墨烯量子點的質量比為5:1,熱處理溫度為700℃時,F-GQDs的氟原子摻雜量為23%,N-GQDs的氮原子摻雜量高達4.25%,對于未氟化直接進行氮摻雜的N-GQDs樣品,氮原子摻雜量僅為1.6%,說明采用摻氟預處理的階躍分步摻雜法能顯著提高氮原子的摻雜量。3、摻雜型石墨烯量子點的性能。(1)光致發(fā)光性能:N-GQDs的熒光光譜較未摻雜GQDs藍移20 nm,量子產率提高1.5倍,紫外燈照射下的發(fā)光顏色由黃色變?yōu)辄S綠色,N-GQDs的熒光強度隨添加Fe~(3+)濃度的升高而顯著降低;(2)電催化性能:N-GQDs 700在0.1MKOH堿性條件下的半波電位和極限電流密度分別為0.76 V、3.69mAcm~(-2)(催化劑載量600μg cm~(-2)),經(jīng)過2500圈循環(huán)后,分別衰減2.4%、2.7%;采用一步溶劑熱法合成四氧化三鈷與氮摻雜石墨烯量子點納米復合物(Co_3O_4@N-GQDs)。Co_3O_4@N-GQDs 450在0.1M KOH堿性條件下的半波電位和極限電流密度分別為0.77 V、5.48 mA cm~(-2)(催化劑載量600μg cm~(-2)),經(jīng)過2500圈循環(huán)后,半波電位衰減0.7%,極限電流密度略有降低,對比N-GQDs 700催化劑其催化活性增強,穩(wěn)定性提高。本文為摻雜型石墨烯量子點在光致發(fā)光應用于生物醫(yī)療領域提供了思路,開發(fā)出低成本、高效的非金屬氧還原催化劑,為摻雜型石墨烯量子點在能源材料領域的應用提供理論依據(jù)和技術支持。
[Abstract]:Graphene Quantum Dots (Graphene Quantum Dots,GQDs) have remarkable quantum limiting effect, boundary effect and good biological compatibility, in fluorescence labeling, microsensor, targeted medical treatment, etc. Biological tracer and electrocatalysis have great application prospects. Doping can effectively regulate the crystal and electronic structure of graphene quantum dots, thus changing their photoluminescence and electrocatalytic properties. At present, there are still many problems in the industrial application of graphene quantum dots, such as controllable preparation, modification and low cost production. In this paper, graphene quantum dots were prepared from carbon fiber and graphite powder by strong oxidation etching, and a step doping method, which can significantly increase the doping amount of graphene based materials, was proposed. The doped graphene quantum dots and their nanocomposites were successfully prepared and used in photoluminescence and electrocatalysis. The main work of this paper is as follows: 1. Controllable preparation of graphene quantum dots. Graphene quantum dots were prepared with carbon fiber (Carbon Fibers) and graphitic powder (Graphite Powders) as raw materials. The experimental results show that the particle size of the two graphene QDs is less than 6 nm, and the fluorescence quantum yields are 2% (quinine sulfate as reference), respectively, showing a remarkable fluorescence dependence on the excitation wavelength. 2. Doping of graphene quantum dots. Fluorine-doped graphene quantum dots (F-GQDs) were prepared first (Fluorine-doped GQDs), increased the internal defect concentration of GQDs, and then N-GQDswith controllable nitrogen atom ratio were prepared by ammonia nitrogen treatment at high temperature. The experimental results show that when the mass ratio of fluorides to graphene quantum dots is 5: 1 and the heat treatment temperature is 700 鈩，

本文編號：2342089