Koç I, Ozer M, Ozkaya A R, Bekaroğlu O
Department of Chemistry, Marmara University, 34722, Göztepe-Istanbul, Turkey.
Dalton Trans. 2009 Aug 28(32):6368-76. doi: 10.1039/b905614a. Epub 2009 Jun 24.
Electrocatalytic activity, methanol tolerance and stability of three phthalocyanine (Pc) complexes (a heptadecafluorononyl-substituted mononuclear CoPc 1, a pentaerythritol-bridged ball-type dinuclear Co2Pc2 2 and a heptadecafluorodecyl-substituted, pentaerythritol-bridged ball-type dinuclear Co2Pc2 3) and the performance of dual catalysts of 2/Pt and 3/Pt, dispersed on a high surface area carbon substrate, Vulcan XC-72 (VC) and Nafion (Nf), towards oxygen reduction (OR) were investigated and compared by surface cyclic voltammetry, rotating disk electrode, rotating ring-disk electrode and chronoamperometry experiments in acidic medium. The VC/Nf/3 modified glassy carbon electrode showed much higher catalytic performance, compared to VC/Nf/2 and VC/Nf/1 modified ones. The long term stability of the VC/Nf/3 catalyst in acidic medium was better than that of VC/Nf/2. It was found that the VC/Nf/1, VC/Nf/2 and VC/Nf/3 catalysts are nearly insensitive to the presence of methanol. In the presence of 1 M methanol in the electrolyte, the catalytic performances of 2- and 3-based catalysts were much better than that of the Pt-based one. Thus, it was shown that the VC/Nf/2-Pt and VC/Nf/3-Pt dual catalysts can be good alternatives to VC/Nf/Pt as cathode catalysts in direct methanol fuel cells. Moreover, in the absence of methanol, the mixing of 3 with Pt resulted in the enhancement of catalytic activity for OR, when compared to 3 and even Pt in the high overpotentials region.
通过在酸性介质中进行表面循环伏安法、旋转圆盘电极、旋转环盘电极和计时电流法实验，研究并比较了三种酞菁（Pc）配合物（一种十七氟壬基取代的单核钴酞菁1、一种季戊四醇桥联球型双核Co₂Pc₂ 2和一种十七氟癸基取代、季戊四醇桥联球型双核Co₂Pc₂ 3）的电催化活性、甲醇耐受性和稳定性，以及负载在高比表面积碳载体Vulcan XC - 72（VC）和Nafion（Nf）上的2/Pt和3/Pt双催化剂对氧还原（OR）的性能。与VC/Nf/2和VC/Nf/1修饰的玻碳电极相比，VC/Nf/3修饰的玻碳电极表现出更高的催化性能。VC/Nf/3催化剂在酸性介质中的长期稳定性优于VC/Nf/2。发现VC/Nf/1、VC/Nf/2和VC/Nf/3催化剂对甲醇的存在几乎不敏感。在电解液中存在1 M甲醇的情况下，基于2和3的催化剂的催化性能比基于Pt的催化剂要好得多。因此，结果表明，作为直接甲醇燃料电池的阴极催化剂，VC/Nf/2 - Pt和VC/Nf/3 - Pt双催化剂可以很好地替代VC/Nf/Pt。此外，在没有甲醇的情况下，与3甚至在高过电位区域的Pt相比，3与Pt混合导致OR催化活性增强。
