乙醇電氧化在過渡金屬上反應研究

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2013

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本研究,利用一系列的金屬催化劑,包括Rh、Ir、Pd、Pt、Au、Ru、Cu、Co、Ni、Ag等十種金屬,在酸性和鹼性條件下對乙醇電氧化反應做有系統的研究。 利用含浸還原法製備金屬催化劑,並加入NaBH4當作還原劑,使金屬還原並吸附在Vulcan XC-72上。合成出來的樣品粉末會先經由XRD、SEM、EDX和TEM的測試,藉此來確認它們的結構、組成、和顆粒大小,接著在把合成出來的金屬觸媒吸附到玻璃碳電極上做電化學的測試。利用循環伏安法做電化學的測試,藉由掃描出來的圖譜,可以得到氫氣吸脫附和CO脫除的訊號,經由計算可以得到金屬催化劑的表面活性面積。金屬催化劑對乙醇電氧化反應活性的研究,則利用循環伏安法和計時安培法,在包含1M乙醇的酸性(0.5M H2SO4)和鹼性(0.1M KOH)溶液當中,測試電氧化活性和抗毒化的能力。 綜合電化學的結果可以得到幾個結論:(1) 一般認為Pt在酸性條件下,而Pd在鹼性條件下時,對於乙醇電氧化能力是較好的金屬催化劑;Au 則具有不錯的抗毒化能力。(2) 當金屬催化劑的顆粒大小越小時,乙醇電氧化的效能會越好;而提高金屬的比例不一定就會提升乙醇電氧化的效能。(3) 乙醇電氧化的起始氧化電位越低,氧化峰的電位也會越低,氧化峰的電流強度會越高。 關鍵字:電氧化、過渡金屬、乙醇、一氧化碳脫除
In this study, electrooxidation of ethanol on a series of metal-based catalysts, including, Rh, Ir, Pd, Pt, Au, Ru, Cu, Co, Ni and Ag, have been systematically investigated in both acidic and alkaline media. The electrocatalyst were prepared by the impregnation reduction method, as metals were reduced by NaBH4 and deposited on Vulcan XC-72.The fabricated sample powder were initially examined by XRD, SEM, EDX and TEM to confirm their microstructure, chemical composition and particle size and deposited on glassy carbon electrode for the electrochemical measurement. The electrochemical measurement by cyclic voltammogtams (CVs) for hydrogen adsorption/desorption and CO stripping, were used to calculate the metal active surface of the working electrode. The promoting activity of catalysts for ethanol electrooxidation reaction was examined by CV and chronoamperometry (CA) measurements for 1M ethanol in boths acidic (0.5M H2SO4) and alkaline (0.1M KOH) conditions to investigate the electrooxidation active and antipoisoning stability of the catalysts, respectively. The electrochemical results can be obtained in several conclusions:(1) Pt and Pd sre considered as the best catalysts for ethanol electrooxidation acidic and alkaline media, repectively; while Au shows excellent antipoisoning behavior. (2) The smetallic catalysts with smaller particle sizes can provide better electro-catalystic performance: while their loadings play insignificant role. (3)The lower onset potential for ethanol oxidation will reduce and increase the oxidationpeak potential and its current intensity, respectively. keywords: electrooxidation、transition-metal、ethanol、CO stripping

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電氧化, 過渡金屬, 乙醇, 一氧化碳脫除, electrooxidation, transition-metal, ethanol, CO stripping

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