鉑錫與第三元金屬的三元合金觸媒對於乙醇氧化反應表現與機構之探討

Abstract

此次研究主要探討碳黑XC-72上的三金屬觸媒PtSnM（M = Ag，Rh，Pd，Co，Cu）對於乙醇氧化反應（EOR），直接乙醇燃料電池（DEFC）的陽極反應。所有三元合金觸媒都以含浸法合成，利用能量色散X射線光譜儀(EDS)、粉末式X光繞射分析儀(XRD)及X光光電子光譜儀(XPS) 來分別鑑定各元素的組成，晶體結構和氧化態。電化學實驗以循環伏安法(CV) 檢測合成的催化劑以研究反應活性面積(ECSA) 和乙醇氧化反應(EOR) 活性，而以計時電流法（CA）檢測合成的催化劑的穩定性。此外，我們採用傅立葉轉換紅外光譜儀(FTIR) 來研究反應中產生的中間體和產物，以便了解其反應機制。在我們的電化學結果中可以發現PtSnAg和PtSnCu具有更好的EOR活性和穩定性，其中PtSnAg具有最佳的EOR活性和穩定性;它們的催化性能的提高可以歸因於添加了Ag和Cu導致Pt0/ Ptn +的比例增加。我們在最後改變了電化學反應中最佳的三金屬PtSnAg的組成，並發現了具有最佳EOR性能的催化劑Pt3Sn1Ag1。另外在傅立葉轉換紅外光譜(FTIR) 通過主要產物為形成乙酸的四電子氧化路徑來判別PtSnM上的EOR機制。

The present study focuses on the ethanol oxidation reactions (EOR), the anodic reactions for direct ethanol fuel cells (DEFC), on trimetallic PtSnM(M = Ag、Rh、Pd、Co、Cu) on carbon black XC-72. All the ternarycatalysts are synthesized by impregnation method and characterized by Energy dispersive spectroscopy (EDS), X-ray diffraction (XRD),and X-ray photoelectron spectroscopy (XPS) to confirm theircompositions,crystal structuresand oxidation state ofeach element, respectively. The synthesizedcatalysts have then been examined by the electrochemical tests of cyclic voltammetry (CV) to study the ECSAandEOR activity and chronoamperometry (CA)to examine theirstability. Furthermore, we employ in situFTIR to study the intermediates and productsgeneratedin the reaction for the mechanism understanding. Ourelectrochemical results find that PtSnAg and PtSnCu show the better EOR activity and stability, in which PtSnAg has the best one; their enhanced catalytic performance is attributable to increased Pt0/Ptn+ratio induced by the addition of Ag and Cu.Furthermore, we vary the composition of the best PtSnAg trimetal and optimize the Pt3Sn1Ag1catalyst withthe best EOR performance. Also, our FTIR spectra identifythe EOR mechanismon those PtSnM through the four-electron-oxidation pathwayin the formation of acetic acid as the major product.