以過渡金屬修飾鉑/奈米複合碳電極以提升其電化學活性

Enhancement on Electrochemical Activity of Platinum/Carbon Nanotube Composite Electrodes Using Transition Metals

林嘉儀(Chia-Yi Lin)

指導教授 ： 謝建德

元智大學/工程學院/化學工程與材料科學學系/碩士(2008年)

https://doi.org/10.6838/YZU.2008.00249

摘要

本文提供一種自組裝合成多成份奈米纖維之技術，以多層奈米碳管為母體(matrix)，經此技術形成複合奈米碳纖維流程包括(a)植佈酸性官能基(表面氧化處理)、(b)離子交互作用及(c)熱處理三步驟，藉由金屬水合離子與CNT表面具有偶極距官能基之間的引力作用，而使CNT表面鍵結金屬，組裝奈米金屬顆粒於CNT上。藉由此技術可合成金屬及雙金屬奈米顆粒於奈米一維碳材表面，形成複合奈米纖維。本文將探討以過渡金屬修飾鉑/奈米複合碳電極以提升其電化學活性。
我們利用此表面改質技術，可以得到雙金屬觸媒複合材料，從FE-SEM、TEM、XRD與N2物理吸附分析得知，隨著過渡金屬觸媒的修飾，雙金屬觸媒的晶相大小會有不同的影響。我們發現雙金屬複合材料的比表面積與孔徑分布在雙金屬觸媒負載後有些微的改變。利用CV在1M 的H2SO4電解液中實驗，樣品(Co-Pt/CNT)在此酸性電解質系統與甲醇氧化電化學測試中表現出非常良好的電化學活性(活性表面覆蓋率約71.5 %)。結果中電化學活性的增加，我們可以歸因於兩個原因：(a)雙金屬觸媒中，Co的加入使得H2O電解之需求電位降低並促使碳基材氧化；(b) Co-Pt/CNT觸媒中，Co的存在使Pt-COads易於還原。

關鍵字

自組裝機制 ； 奈米碳管 ； 循環伏安法 ； 電化學活性 ； 過渡金屬

並列摘要

In the present work, we propose an efficient method to fabricate metal particulates deposited on CNTs, which consists of the following steps: (a) implantation of acidic groups, (b) ionic interaction, and (c) heat treatment. In the self-organization nanostructure, the major formation mechanism is to utilize the strong interaction between metal ions and oxygen functional groups and the sidewall of carbon nanomaterials.
CNT decorated with different transitional metal nanocatalysts were fabricated to investigate their electrochemical activity in acid solution. These transitional metal dxides/CNT composites were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and N2 physisorption. The crystalline size of nanocatalysts generally effect with transition metals. The specific surface areas and pore size distributions of transition metal/CNT composites were slightly altered after the transition metals deposition. Cyclic voltammetry measurements in 1 M H2SO4 and in 0.5 M H2SO4 containing 1 M methanol showed that Co-Pt/CNT electrode has the greatest activity in electrochemical adsorption and desorption of hydrogen, i.e., the ratio of electrochemical surface coverage: 71.5 %. This enhancement of electrochemical activity was attributed to two possible reasons: (a) addition of Co in the bimetallic catalysts leads to reduce the required potential for water electrolysis and thus the associated carbon oxidation; (b) the presence of Co in the bimetallic alloys acts an important role in regenerating inactive Pt–COads sties.

並列關鍵字

Self-organization ； Carbon nanotubes ； Electrochemical activity ； Cyclic voltammetry ； Transition metals

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