Pt–MoOx-carbon nanotube redox couple based electrocatalyst as a potential partner with polybenzimidazole membrane for high temperature Polymer Electrolyte Membrane Fuel Cell applications
Pt–MoOx-carbon nanotube redox couple based electrocatalyst as a potential partner with polybenzimidazole membrane for high temperature Polymer Electrolyte Membrane Fuel Cell applications
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DOI：
10.1016/j.electacta.2010.01.012
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发表时间：
2010-03
影响因子：
6.6
通讯作者：
Ranjith Vellacheri;Sreekuttan M. Unni;S. B. Nahire;U. K. Kharul;Sreekumar Kurungot
中科院分区：
文献类型：
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作者：
Ranjith Vellacheri;Sreekuttan M. Unni;S. B. Nahire;U. K. Kharul;Sreekumar Kurungot
制备基于氧化还原对的电催化剂，其包含用氧化钼（MoOx，2<x<3）纳米颗粒促进的Pt-多壁碳纳米管（Pt-MWCNT）。我们的目标是有效地组织光滑的MWCNT表面上的Pt-MoOx界面，以克服与建立这样的界面与Pt分散在具有表面不规则性的碳形态相关的实际困难。本研究揭示了严格控制添加剂水平的重要性，以通过组分的协同效应和在高温下可操作的质子传导膜的需要来保持催化剂组合的平衡的双功能行为，以从聚合物电解质膜燃料电池（PEMFC）系统获得更好的输出。一个本土开发的聚苯并咪唑（PBI）膜被用来制造膜电极组件（MEA），因为它可以在更高的温度下运行相比，Nafion膜。通过循环伏安法监测活性Pt面积来仔细控制MoOx添加剂水平。采用HRTEM、XRD和XPS等手段对催化剂进行了表征，分别考察了催化剂中不同元素的分散度、形貌、结晶度和氧化态。相对于Pt添加5%MoOx制备的体系（以下称为Pt-MoOx（5%）-MWCNT）显示出平衡的活性Pt面积和优异的氧还原反应（ORR）和甲醇氧化反应（莫尔）活性。旋转圆盘电极（RDE）系统被广泛用于了解ORR动力学和MoOx作为促进剂在反应中的有利作用。与不含添加剂的体系相比，在0.02V vs. Hg/Hg 2SO 4电极下从Koutecky-Levich图测量的动力学电流（jk）高9倍，并且在单电池评价期间，MoOx促进的体系的表观活化能低27 kJ/mol。较高的操作温度通过PBI膜的质子传导率的增强的组合效应和通过在涉及此类系统的一些组合中的MoOx型系统的充分假设的氧溢出效应的可能动力学益处显著有利于电池性能。
A redox couple based electrocatalyst comprising of Pt-Multi Wall Carbon NanoTube (Pt-MWCNT) promoted with molybdenum oxide (MoOx, 2<x<3) nanoparticles was prepared. The objective was to effectively organize the Pt–MoOxinterface on the smooth MWCNT surface to overcome the practical difficulties associated with establishing such interface with Pt dispersed on carbon morphologies possessing surface irregularities. The present study revealed the importance of stringent controlling of the additive level for maintaining a balanced bifunctional behavior of the catalyst combination through the synergistic effects by the components and the need of a proton conducting membrane operable at high temperature to get better output from the Polymer Electrolyte Membrane Fuel Cell (PEMFC) systems. An indigenously developed polybenzimidazole (PBI) membrane was used to fabricate a membrane electrode assembly (MEA) as it can be operated at higher temperatures compared to that of Nafion membranes. MoOxadditive level was carefully controlled by monitoring the active Pt area by cyclic voltammetry. All prepared electrocatalysts were characterized by using HRTEM, XRD and XPS to get information on dispersion and morphology, crystalinity and oxidation state of different elements, respectively. The system prepared with 5% MoOxaddition with respect to Pt (hereafter Pt–MoOx(5%)-MWCNT) displayed balanced active Pt area and excellent oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) activities. Rotating Disk Electrode (RDE) system was extensively utilized to understand the ORR kinetics and the favorable role of MoOxas the promoter in the reaction. The kinetic current (jk) measured at 0.02V vs. Hg/Hg2SO4electrode from the Koutecky–Levich plots was 9 times higher and the apparent activation energy during single cell evaluation was 27kJ/mol lower for the MoOxpromoted system, compared to the system without the additive. A higher operating temperature significantly favored the cell performance by a combined effect of enhancement in proton conductivity of the PBI membrane and possible kinetic benefit by the well postulated oxygen spill over effect by the MoOxtype systems in some combinations involving such systems.