二烷基咪唑陽離子前趨物在石墨基材生成金屬奈米粒子及其性質與電催化應用之研究

對醇類或羧酸類之氧化反應的催化劑製備過程中，通常為了避免使用貴重金屬鉑，乃將其它或多種元素製成不同形狀或大小的奈米材料，以提升催化效能。本研究選用鈀、鉑及錫等元素，將其合成為奈米粒子，作為氧化甲醇、乙醇及甲酸的催化劑，並用高定向熱解石墨為基材，以避免因基材過小而須再組裝成電極時，可能消耗已製得的催化劑。合成奈米粒子時，利用前趨物吸附與反應作為合成步驟，並以二烷基咪唑鹽為奈米粒子前趨物。利用咪唑陽離子對石墨基材的作用力及烷基在非極性環境下的穩定性，使生成的奈米粒子可以散佈在基材表面。本研究所製得之奈米材料經由表面分析，確認其奈米粒子具有較佳的表面分散性及大小分布。此外，研究結果顯示，藉由修飾基材表面與增修合成步驟，可調整奈米粒子的大小與密度或生成多元素之奈米粒子。上述氧化反應利用循環伏安法與計時安培法之測定，發現，以咪唑陽離子為前趨物所製作的產物對催化反應有較佳的效果。由於目前碳基材已被廣範應用於各個領域，此法可望使用於生成不同奈米粒子在於其它碳材上。除了能生成較小且分散之奈米粒子，亦能同時達到以少量反應物來進行大尺寸材料製備的效果。

關鍵字

電化學；電催化；甲酸；鈀；奈米粒子；咪唑；石墨基材

並列摘要

To avoid taking noble metal (ex: Platinum) as catalyst to oxidize alcohol or carboxylic acid, people use other element to produce different structure or size to enhance catalyst activity. In our research, we synthesized the nanoparticles from palladium, platinum and tin on highly oriented pyrolytic graphite (HOPG) to be the catalyst for oxidation of methanol, alcohol and formic acid. Using highly oriented pyrolytic graphite (HOPG) as substrate due to it didn’t need to restructure to suitable size for the electrode and the product of catalyst might be consumed in this procedure. We used adsorption and reaction steps to synthesize the nanoparticles on the HOPG from dialkylimidazolium precursor. The nanoparticles would be dispersed on the HOPG by the interaction between graphitic substrate and imidazolium and by the stability of alkyl group in inert condition. The nanomaterials was confirmed the enhancement of dispersion and size distribution by the surface analysis in this study. Furthermore, we could adjust the size and density of nanoparticles and produce bimetal nanoparticles by substrate treatment and modification of synthesis of nanoparticles. The performance of catalytic oxidation reaction was detected by cyclic voltammetry and chronoamperometry. The product made from imidazolium precursor got better performance of catalytic oxidation than normal precursor. Due to carbon substrates were applied in different fields popularly, our method might produce different nanoparticles on other carbon substrates. Besides producing small and dispersed nanoparticles, out method could synthesize nanoparticles on the large area substrate and low consumption of precursor simultaneously.

並列關鍵字

electrochemical ； electrocatalytical ； formic acid ； palladium ； nanoparticle ； imidazolium ； HOPG

參考文獻

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[3] Susut C., Nguyen T., Chapman G., Tong Y., Shape and size stability of Pt nanoparticles for MeOH electro-oxidation. Electrochim. Acta. 2008, 53, 6135

[4] John L.H., Kristin M.S., Richard I.M., Effects of Addition of Antimony, Tin, and Lead of Palladium Catalyst Formulations for the Direct Formic Acid Fuel Cell. J. Phys. Chem. C 2010, 114, 11665-11672.

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二烷基咪唑陽離子前趨物在石墨基材生成金屬奈米粒子及其性質與電催化應用之研究

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