銅鈀奈米粒子之合成及其在無電鍍銅之應用

The Synthesis of Cu/Pd Nanoparticles and Its Application to Electroless Copper Deposition

羅曉筠(Hsiao-Yun Lo)

指導教授 ： 王詠雲 ； 萬其超

國立清華大學/工學院/化學工程學系/博士(2008年)

https://doi.org/10.6843/NTHU.2008.00186

摘要

Cu/Pd bimetallic nanoparticles have been successfully synthesized in the ambient condition with the aid of complexing agent, trisodium citrate and EDTA. XRD and XPS results show low degree of oxidation in Cu/Pd nanoparticles in citrate and EDTA systems. The TEM images reveal that the synthesized nanoparticles were well-dispersed and about 5 nm in diameter. The quenched XANES method was employed to investigate the formation mechanism of Cu/Pd nanoparticles with citric complexing agent. Two-stage and three-stage mechanisms were proposed for Cu/Pd molar ratio = 1/1 and 1/2 systems, respectively. The former was expected to have more Cu on surface while the latter had Pd enriched on surface. The Cu/Pd nanoparticles synthesized with citric complexing agent in different molar ratios were further tested as activator for electroless copper deposition. The nanoparticles with Cu/Pd = 1/2 was found to have catalytic ability comparable to traditional Pd/Sn colloid or pure Pd activator among all the bimetallic Cu/Pd systems. The most concerned long-term stability of Cu/Pd nanoparticles was investigated by XANES. Although slow Pd oxidation and Cu dissolution were found in Cu/Pd colloidal solution when exposed to air, the stability of these Cu/Pd nanoparticles was still acceptable in industrial application. In short, stable Cu/Pd nanoparticles have been successfully synthesized with citric complexing agent and showed high potential to be applied as activator in electroless copper deposition.

關鍵字

奈米粒子 ； 無電鍍銅 ； 觸媒 ； X光吸收光譜

並列摘要

本文主要探討水溶液中銅鈀奈米粒子的合成，此合成方法是透過添加檸檬酸或EDTA錯合劑至前驅鹽溶液中，使形成穩定的金屬錯合離子後，以甲醛還原金屬錯合離子成奈米級金屬微粒，以高分子型(PVP)保護劑形成立體障礙防止合成的粒子聚集沉澱。錯合劑除了改變金屬離子的還原電位外，亦可有效防止氫氧化物雜質的產生。
經過穿透式電子顯微鏡的觀察，以檸檬酸錯合劑合成的銅鈀奈米粒子分散尤其良好，並具有均一的粒徑分布(3 nm ~ 4 nm)，X光粉末繞射結果發現此奈米粒子確實是以雙金屬的型態存在。根據電子能譜儀的結果顯示，合成的銅鈀奈米粒子在表面上有些微的氧化，其氧化可能的原因為與保護劑的化學鍵結或是受氧氣的氧化所造成，然此奈米粒子的內部仍維持金屬的還原態。經過X光吸收光譜的分析，可以推測出可能的金屬錯合離子還原機構，不同的金屬前驅鹽比例會以不同的機制進行還原反應。在銅鈀比為1：2的系統中，還原反應主要可分為三部分，第一為鈀錯離子的成核，第二階段為銅錯離子還原及少量的鈀金屬還原，待大量的銅離子還原完後，進入還原反應的第三個階段，溶液中只剩鈀錯離子可繼續進行反應，最終有效形成較多鈀分布在表面的奈米粒子，此種奈米粒子具有較低的貴金屬鈀含量而仍具有鈀金屬的高催化活性。在銅鈀比為1：1的系統中，還原反應主要可分為二步驟，先為鈀核的形成而後為銅離子在鈀核上還原，因而形成以銅金屬為主的外層結構。
將此種銅鈀奈米粒子應用在無電鍍銅的催化上，可以較簡便的流程進行無電鍍銅之催化反應，除了鈀金屬的含量之外，奈米粒子的外層結構或是PVP層包覆的型態亦有可能影響最終的催化鍍銅效果。銅鈀比為1:2的系統具有最高的催化活性，其催化鍍銅效率與傳統錫鈀膠體或是純鈀金屬相當。此外，此種銅鈀奈米粒子具有相當的穩定度，曝露在空氣中雖會有緩慢的鈀氧化與銅溶解現象，但仍具有穩定的懸浮能力與催化活性。整體而言，以檸檬酸錯合劑合成之銅鈀奈米粒子具有相當高的應用潛力。

並列關鍵字

nanoparticle ； electrless copper deposition ； catalyst ； EXAFS

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