Oxygen Reduction Activity of a Copper Complex of 3,5-Diamino-1,2,4-triazole Supported on Carbon Black
Oxygen Reduction Activity of a Copper Complex of 3,5-Diamino-1,2,4-triazole Supported on Carbon Black
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DOI：
10.1002/anie.200803554
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发表时间：
2009-01-01
影响因子：
16.6
通讯作者：
Gewirth, Andrew A.
中科院分区：
文献类型：
--
作者：
Thorum, Matthew S.;Yadav, Jessica;Gewirth, Andrew A.
氧还原反应（ORR）的电催化目前因其在燃料电池阴极中的应用而受到广泛关注。缓慢的反应动力学显著影响燃料电池的效率，并且即使使用Pt催化剂，ORR的开始也发生在约1.0V，这远低于相对于可逆氢电极（RHE）的1.23V的氧还原的可逆电势。[1]多铜氧化酶（以漆酶为例）在含有三个间距约为3.5的Cu原子的位点处活化氧，并且在接近1.2V（相对于RHE）的电位下表现出显著的ORR电活性。[2，3]考虑到Pt的高成本和有限供应，吸附在电极表面上的表现出这种反应性水平的含铜络合物将是非常期望的。很少有报道显示出显著ORR活性的合成Cu络合物。用石墨电极吸附法研究了几种单核铜配合物。[4-9]由Zhang和安森推广的Cu Ⅱ与邻菲咯啉配体的配合物[6]是迄今为止研究得最好的。McCrory埃塔尔已经研究了各种取代的菲咯啉的Cu络合物，其中最好的证明了在pH 4.8下约0.68 V（RHE）的ORR起始，并且得出结论，通过使用该系统不可能进一步增加活性。[7]使用假定的多铜络合物的尝试包括通过在六氮杂大环配体中配位两个CuII离子形成的水溶性催化剂，[10]和用含有CuII离子的溶液浇铸聚合物修饰的电极，包括铜-聚（组氨酸）络合物，[11]和聚合的CuII络合物。[12]然而，当吸附在任何这些系统中的电极上时，缺乏多核性的证明。还通过吸附到石墨上研究了具有Cu-Fe位点的细胞色素c氧化酶模型化合物，但ORR起始在约0.2 V相对于RHE是相当低的，并且仅含有Fe的复合物具有类似的活性。[13个国家]
Electrocatalysis of the oxygen reduction reaction (ORR) is currently of widespread interest because of its application in fuel-cell cathodes. Slow reaction kinetics significantly impact the efficiency of fuel cells and, even with Pt catalysts, the onset of the ORR occurs at approximately 1.0 V, which is well below the reversible potential for oxygen reduction of 1.23 V versus the reversible hydrogen electrode (RHE).[1] Multicopper oxidases (exemplified by laccase) activate oxygen at a site containing three Cu atoms with spacings of approximately 3.5 and exhibit remarkable ORR electroactivity at potentials approaching 1.2 V (versus RHE).[2, 3] Given the high cost and limited supply of Pt, a copper-containing complex adsorbed on an electrode surface that exhibited this level of reactivity would be highly desirable. There are few reports of synthetic Cu complexes that exhibit significant ORR activity. Several mononuclear Cu complexes have been investigated by adsorption onto graphite electrodes.[4–9] CuII complexes with phenanthroline ligands, which were popularized by Zhang and Anson,[6] are the beststudied to date. McCrory etal. have investigated the Cu complexes of a variety of substituted phenathrolines, the best of which demonstrated an ORR onset of about 0.68 V (RHE) at pH 4.8, and concluded that further increases in activity were unlikely by using this system.[7] Attempts that used putative multicopper complexes include a water-soluble catalyst formed by the coordination of two CuII ions in a hexaazamacrocyclic ligand,[10] and electrodes modified with solution-cast polymers containing CuII ions, including a copper–poly (histidine) complex,[11] and a polymeric CuII oxalato complex.[12] However, the demonstration of polynuclearity when adsorbed on an electrode in any of these systems is lacking. A cytochrome c oxidase model compound with a Cu–Fe site has also been investigated by adsorption onto graphite, but the ORR onset is quite low at about 0.2 V versus RHE and the complex that contains only Fe has similar activity.[13]