鈀鉑與鈀鉑合金觸媒對於甲乙醇氧化反應表現與機構之探討
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2017
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本研究主要探討在碳黑(XC-72)上Pt、Pd、PtPd不同比例分別為3:1, 1:1, 1:3(以下寫作Pt3Pd1,Pt1Pd1,Pt3Pd1)觸媒對於直接甲醇(乙醇)燃料電池中的甲醇(乙醇)氧化反應中的陽極反應，在實驗中所用到的合金觸媒皆為含浸法合成，並且使用XRD、SEM、EDS去鑑定物理性質，接著將觸媒放在1M KOH中曝氮氣再使用電化學CV測量ECSA，再分別利用CV及CA測量1M甲醇和乙醇的電催化活性和穩定度。結果顯示合金的活性和穩定度都優於純Pt與Pd其中Pt3Pd1有著最高的MA(1279 mA/ugPt)及SA65(mA/cm2)而Pt1Pd1有著最好的穩定性(經過90分鐘CA測試後仍有原本51%的電流)。進一步利用ex-FTIR來偵測溶液中的2,4,6電子產物(HCHO, HCOOH, CO32-)隨著CV圈數的變化來推測觸媒在MOR的機制，圖譜顯示所有的合金都有些微的差異，其差異趨勢與CA的結果相同。
The present study mechanistic investigates methanol/ethanol oxidation reactions (MOR/EOR), the anodic reactions for direct methanol/ethanol fuel cells (DMFC/DEFC), on Pt, Pd and their alloys with the ratios of Pt/Pd = 3:1, 1:1, 1:3 (denoted as Pt3Pd1, Pt1Pd1 and Pt1Pd3) on carbon black XC-72. All the metallic electrodes were fabricated by the impregnation method and characterized by X-ray diffraction (XRD), Secondary electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The fabricated electrodes were examining by cyclic voltammetry (CV) in 1 M KOH purged with N2 to determine their electrochemical surface area (ECSA). The MOR/EOR activity and stability of the electrodes were investigated by CV and chronoamperometry (CA), respectively, in 1 M methanol/ethanol in alkaline solution of 1 M KOH. The electrochemical tests showed that all the alloys has better both activity and stability than pure Pt and Pd; among them Pt3Pd1 has the best activity with mass activity (MA) =1279 (mA/ugPt)and surface activity (SA) = 65(mA/cm2), and Pt1Pd1 has the best stability (51% decay in 90 minutes CA). The MOR performance was further examined by ex-situ FT-IR to determine the variations of products of HCHO, HCOOH and CO32-(in two, four and-six electron reactions) with CV cycles. The spectroscopic results show that all the alloys have smaller variations, indicating the better stability and agreeing with the CA results.
The present study mechanistic investigates methanol/ethanol oxidation reactions (MOR/EOR), the anodic reactions for direct methanol/ethanol fuel cells (DMFC/DEFC), on Pt, Pd and their alloys with the ratios of Pt/Pd = 3:1, 1:1, 1:3 (denoted as Pt3Pd1, Pt1Pd1 and Pt1Pd3) on carbon black XC-72. All the metallic electrodes were fabricated by the impregnation method and characterized by X-ray diffraction (XRD), Secondary electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The fabricated electrodes were examining by cyclic voltammetry (CV) in 1 M KOH purged with N2 to determine their electrochemical surface area (ECSA). The MOR/EOR activity and stability of the electrodes were investigated by CV and chronoamperometry (CA), respectively, in 1 M methanol/ethanol in alkaline solution of 1 M KOH. The electrochemical tests showed that all the alloys has better both activity and stability than pure Pt and Pd; among them Pt3Pd1 has the best activity with mass activity (MA) =1279 (mA/ugPt)and surface activity (SA) = 65(mA/cm2), and Pt1Pd1 has the best stability (51% decay in 90 minutes CA). The MOR performance was further examined by ex-situ FT-IR to determine the variations of products of HCHO, HCOOH and CO32-(in two, four and-six electron reactions) with CV cycles. The spectroscopic results show that all the alloys have smaller variations, indicating the better stability and agreeing with the CA results.
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乙醇氧化反應, 甲醇氧化反應, 非即時性傅立葉紅外線光譜儀, 鈀鉑合金觸媒, 比例效應, ratio effect, EOR, MOR, PtPd alloy catalyst, ex situ FT-IR, CO-stripping