聚乙烯醇包覆奈米銀觸媒(PVA-Ag)之合成及其應用在無電電鍍銅反應催化之研究

Synthesis of PVA-Capped Ag Nanoparticles and Its Application in Electroless Cu Deposition

葉哲銘(Che-Ming Yeh)

指導教授 ： 衛子健

國立清華大學/工學院/化學工程學系/碩士(2018年)

摘要

在無電電鍍的程序中，鈀是最常用的活化觸媒。由於商用鈀觸媒的不穩定性以及鈀金價格日趨昂貴的趨勢下，因此探尋非鈀系統的無電電鍍觸媒在產學研界都引發了相當大的興趣。本研究的主要目標為開發一新型奈米銀觸媒，以PVA為保護劑、甲醛和硼氫化鈉為還原劑下進行銀觸媒的合成，並搭配表面氫氧化以及矽烷化合物之兩階段表面改質將觸媒吸附於基板上進行無電電鍍銅的測試。
在研究的第一部分，依循前人的研究，以甲醛為還原劑搭配氫氧化鈉為pH調整劑下進行銀觸媒的合成，在穿透式電子顯微鏡(TEM)以及動態奈米粒徑散射分析儀(DLS)的分析下，發現合成出之銀觸媒的粒徑尺寸過大，粒徑分布亦不理想。進而藉由掃描式電子顯微鏡(SEM)、傅立葉轉換紅外光譜儀(FTIR)、核磁共振(NMR)、TEM以及原子力顯微鏡(AFM)的分析下，證明了造成粒徑過大的原因為PVA保護劑與甲醛會在強鹼環境下有著交聯反應的發生，並且隨著交聯反應程度的高低會使合成出來的銀觸媒粒徑有所差異。
第二部分的研究中，由於甲醛不適用於PVA系統下的合成，因此透過硼氫化鈉為新的還原劑進行銀奈米觸媒的合成，在DLS、TEM的分析下，成功的合成出粒徑約13奈米且粒徑分布收斂之銀奈米觸媒，經由X光繞射儀(XRD)、紫外光/可見光分光光譜儀(UV/VIS)的分析，結果顯示銀觸媒皆為純銀且無氧化物的生成。在後續無電電鍍銅催化上，將觸媒吸附於兩階段表面改質之基板進行測試，從測試的結果發現，銀觸媒並無法在無電電鍍銅的反應上順利進行催化，透過感應耦合電漿質譜儀(ICP-MS)、X光射線電子能譜儀(XPS)、觸媒活性檢測(induction time)的檢測下確認銀觸媒在活性以及吸附量與鈀觸媒相比都有著較為不好的表現。在吸附量方面，原因為銀觸媒與ETAS(3-2-(2-aminoethylamino) ethylamino propyl trimethoxysilane)上之胺基並無良好的交互作用力使吸附於基表面的觸媒數量過少;在活性方面，由於銀觸媒本身並無優異的吸氫能力，在催化機制上少了氫的氧化反應式，使得銀觸媒在催化上電子釋放的能力與鈀觸媒相比遜色許多。

關鍵字

銀奈米 ； 無電電鍍銅

並列摘要

Palladium is the most popular catalyst being used in the electroless deposition process. Owing to the instability and expensive price of commercial palladium catalysts, a new type of silver catalyst with polyvinyl alcohol (PVA) as protector, formaldehyde (HCHO) and sodium borohydride (NaBH4) as reducing agent were developed.
In the first part of this research, according to the literature study, HCHO and sodium hydroxide (NaOH) are used as the reducing agent and pH controller for synthesizing silver nanoparticles. From the transmission electron micro scope (TEM), the dynamic light scattering (DLS) results, the silver nanoparticles had large particle size and wide distribution because of the cross-linked reaction between PVA and HCHO. In addition, the analysis of TEM, scanning electron microscope (SEM), fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), atomic force microscope (AFM) further proved that the PVA reacted with HCHO in strong base condition and the different size distribution was related to degree of cross-linked reaction.
As we found in previous section, HCHO is not a suitable reducing agent in PVA-Ag system due to the cross-linking reaction. The second part aims to using NaBH4 as an alternative to HCHO for preparing PVA-Ag nanoparticles. The results from DLS, TEM, X-ray diffraction (XRD) and UV/VIS spectrometers (UV/VIS) illustrated that monodispersed small PVA-Ag catalyst with particle size of 13 nm in average can be found. However, following by depositing PVA-Ag particles on substrate for electroless copper deposition, by means of surface modified with ETAS silane bridging catalysts and the substrate, we discovered that PVA-Ag failed to trigger copper reduction because of the low loading PVA-Ag catalysts, which was confirmed by inductively coupled plasma mass spectrometry (ICP-MS). Further investigations by XPS revealed that the low PVA-Ag loading originated from a weak interaction between Ag particles and the amino group on ETAS. Besides, the induction time measurement indicated a weaker catalytic activity on copper of PVA-Ag comparing to PVA-Pd, where we supposed that PVA-Ag is deficient in hydrogen adsorption, which is an important step in the chain reaction of hydrogen oxidation and then it affects the following copper reduction.

並列關鍵字

Ag nanoparticles ； Electroless Cu Deposition

參考文獻

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