Pd/Fe3O4-C催化剂对甲醇、乙醇和丙醇氧化的电催化活性

制备对醇氧化反应具有优异电活性的钯催化剂是醇燃料电池研究的重要内容。本文用硼氢化钠还原法制备了钯纳米颗粒, 然后沉积在Fe3O4/C复合物表面, 得到了不同Fe₃O₄负载量的Pd/Fe₃O₄-C催化剂. 透射电镜（TEM）图显示钯纳米颗粒均匀地分散在Fe₃O₄/C表面. 对制备好的Pd/Fe₃O₄-C催化剂进行了循环伏安法（CV）、计时电流（CA）和电化学阻抗谱（EIS）的测试, 研究了其在碱性介质中对C1-C3醇类（甲醇、乙醇和丙醇）氧化的电催化活性. 结果表明, 所制备的不同Fe₃O₄负载量的Pd/Fe₃O₄(2%)-C,Pd/Fe₃O₄(5%)-C, Pd/Fe₃O₄(10%)-C和Pd/C催化剂中, Pd/Fe₃O₄(5%)-C催化剂表现出最高的醇氧化电流密度. 依据循环伏安（CV）数据，Pd/Fe₃O₄(5%)-C催化剂对甲醇、乙醇、正丙醇和异丙醇氧化的阳极峰电流密度分别是Pd/C催化剂的1.7、1.4、1.7和1.3倍. Pd/Fe₃O₄(5%)-C催化剂对乙醇氧化的电荷传递电阻也远低于Pd/C催化剂. 制备的所有催化剂对C1-C3醇类电氧化的电流密度大小排序如下: 正丙醇﹥乙醇﹥甲醇﹥异丙醇. 此外, 碳粉中Fe₃O₄纳米颗粒的存在提高了钯纳米颗粒的电化学稳定性.

Electroactivities of Pd/Fe3O4-C catalysts for electro-oxidation of methanol,ethanol and propanol

Development of palladium (Pd) catalysts with high electroactivity for alcohol oxidation is significant for alcohol fuel cells. In this work, Pd nanoparticles were formed by sodium borohydride (NaBH₄) reduction method and subsequently deposited on the surface of carbon supported ferriferrous oxide (Fe₃O₄/C) composites to obtain the Pd/Fe₃O₄-C catalysts with differentFe₃O₄ loadings. Their transmission electron microscopic (TEM) images show that the Pd nanoparticles were uniformly dispersed on theFe₃O₄/C. Electroactivities of the prepared Pd/Fe₃O₄-C catalysts toward oxidations of C1-C3 alcohols (methanol, ethanol, n-propanol and iso-propanol) in alkaline media were investigated by cyclic voltammetry (CV), chronoamperometry and electrochemical impedance spectroscopy. Among the prepared catalysts (Pd/Fe₃O₄(2%)-C, Pd/Fe₃O₄(5%)-C, Pd/Fe₃O₄(10%)-C and Pd/C), the Pd/Fe₃O₄(5%)-C catalyst presented the highest electro-oxidation current density for oxidations of C1-C3 alcohols. According to the CV data, the anodic peak current densities for oxidations of methanol, ethanol, n-propanol and iso-propanol on the Pd/Fe₃O₄(5%)-C catalyst were over 1.7, 1.4, 1.7 and 1.3 times larger than that on the Pd/C catalyst, respectively. Furthermore, the charge transfer resistance of ethanol oxidation on the Pd/Fe₃O₄(5%)-C catalyst was much lower than that on the Pd/C catalyst. For all of the prepared catalysts, the decreases in electro-oxidation current density of the tested C1-C3 alcohols followed the order of n-propanol>ethanol> methanol >iso-propanol. In addition, the presence ofFe₃O₄ nanoparticles in the carbon powder improved the electrochemical stability of the Pd nanoparticles.