以氣相霧化離子方式進行功能複合型奈米粒子 合成方法之研究

Fabrication of Functional Hybrid Nanoparticles Using a Gas-Phase Spray Pyrolysis Approach

賴昭舜(Lai, Chao Shun)

指導教授 ： 蔡德豪

國立清華大學/工學院/化學工程學系/碩士(2015年)

https://doi.org/10.6843/NTHU.2015.00068

摘要

本研究目的為我們使用氣相方法以合成SiO2-Ag複合型奈米粒子(NPs)，並能對其生成粒子之尺寸、組成以及型態結構具有可控制性。研究中採用TEOS與SiO2膠體為前驅物，以分別製備T-SiO2與C-SiO2為SiO2核模板，接著將AgNO3於氣相中沉積於SiO2模板中，並經由氣相鍛燒反應熱裂解AgNO3而形成SiO2-Ag複合奈米粒子。反應系統中我們連同氣相奈米粒子流動分析儀(DMA)，以即時線上分析氣霧化法合成出NPs粒徑大小分布以及數量濃度(i.e.,對應產量)。我們選擇使用熱重量分析儀(TGA)以提供最適化鍛燒溫度資訊，搭配X光繞射儀(XRD)量測奈米粒子之晶體狀態，以分析Ag的轉化程度。我們可知在Tpyrolysis > 500°C鍛燒條件下能使AgNO3完全轉化為Ag；而SiO2核模板的生成與加熱溫度無關。Ag體積以及T-SiO2之大小與前驅物濃度成正比；以C-SiO2而言，我們發現核模板構造可以從小型團簇(如：二聚體，三聚體)調整為次微米大小之大型規則排列團簇，並其C-SiO2之間具有間隙作為孔洞。生成之複合奈米粒子之結構以具有能譜分析儀(EDS)之穿透式電子顯微鏡(TEM)分析，進而提供複合NPs於空間解析上之視覺資訊與元素組成。結果顯示Ag能滲入T-SiO2之孔隙在T-SiO2模板中形成Ag核，且Ag核大小會隨著AgNO3濃度增加而變大。將兩材料混合後，以選用TEOS合成SiO2為核模板時，我們發現Ag核與SiO2殼之形成。藉由選擇C-SiO2為核模板時，複合型NPs之結構轉變成Ag成分分布於多孔型C-SiO2模板中。混合前材料設計之體積和組成與實驗參數條件具有一定關聯性，例如生成粒子體積與前驅物濃度成正比，前驅物組成影響生成複合型奈米粒子之結構與成份比例。我們研究提供一通用方式來達到奈米材料設計，從最適化溫度與前驅物濃度等；並且透過具有良好控制性之合成方法，以期能應用於新興生醫材料(例如藥物傳遞、影像顯影等)及能源相關應用方面(例如燃料添加物、觸媒等)。

關鍵字

銀奈米粒子 ； 氣相合成法 ； 二氧化矽奈米粒子 ； 複合式奈米粒子

並列摘要

In this work we report to use a gas-phase approach to synthesize SiO2-Ag hybrid nanoparticles (NPs) with controlled properties in size, composition, and morphology. TEOS and colloidal silica were used as precursors for fabricating SiO2 core template, and AgNO3 was employed for the precursor of Ag deposits to the SiO2 template. Differential mobility analysis (DMA) was used to in-situ characterize particle size distributions and number concentrations of aerosolized NPs directly in gas phase. Transmission electron microscopy (TEM) with elemental-mapping energy dispersive spectroscopy was employed orthogonally to provide visual information and the elemental composition of these functional hybrid NPs with spatial resolution. Thermogravimetric analysis was chosen to provide the information of the required pyrolysis temperature, and the crystalline state of Ag in the hybrid NPs was confirmed using x-ray diffractometer. Prior to integration, we found T > 500°C was required for a complete pyrolysis of AgNO3 to be Ag, where the SiO2 cores were shown to be less sensitive to the heating temperature. The volume of Ag and the primary size of TEOS-formed SiO2 cores were shown to be proportional to the concentrations of precursors. Using silica colloids as the cores, we found the conformation of cores can be tuned from the finite sized SiO2 clusters to be mesoporous SiO2 sub-micron sized sphere. Results show Ag penetrate into the pore structure of SiO2 to form Ag cores in the SiO2 template, and the core size of Ag was increased with an increase of AgNO3 concentration above the melting point. After integration, we found a formation of Ag-core, SiO2 shell by choose TEOS-synthesized SiO2 as the core template. By choosing colloidal SiO2 as the precursor, the structure of hybrid NPs transferred to be Ag-core with surface decoration in the mesopores of SiO2 template. The related volume and composition were close to the designed value before integration. Our work provides a generic way to implement the design of nanomaterials through a well-controlled synthesis route for emerging biomedical (e.g., drug carriers, imaging agents) and energy applications (e.g., fuel additives, catalysts).

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