Highly active and durable silica-coated Pt cathode catalysts for polymer electrolyte fuel cells: control of micropore structures in silica layers
Highly active and durable silica-coated Pt cathode catalysts for polymer electrolyte fuel cells: control of micropore structures in silica layers
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DOI：
10.1039/c4cy01301h
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发表时间：
2015-01
影响因子：
5
通讯作者：
S. Takenaka;T. Miyazaki;H. Matsune;M. Kishida
中科院分区：
文献类型：
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作者：
S. Takenaka;T. Miyazaki;H. Matsune;M. Kishida
将碳纳米管(CNT)负载铂催化剂用作聚合物电解质燃料电池(PEFC)的阴极组件，通过铂颗粒的烧结或铂离子的溶解和再沉积，在聚合物电解质燃料电池(PEFC)中覆盖一层二氧化硅以防止颗粒尺寸增大。在阴极条件下，3-氨丙基三乙氧基硅烷(APTES)和正硅酸乙酯(TEOS)连续水解生成的氧化硅层显著地提高了催化剂的耐久性，尽管氧化硅涂层材料的氧还原反应活性略低于未涂层催化剂。相比之下，APTES和TEOS在NH_2-(CH_2)_n-NH_2(n=6，8和10)的存在下连续水解制备的二氧化硅包覆的铂/碳纳米管催化剂既具有高的催化活性，又具有良好的耐久性。在SiO_2包覆过程中加入的NH_2-(CH_2)_n-NH_2作为在SiO_2层中形成微孔的模板，所产生的孔结构促进了反应物和产物在SiO_2包覆的铂/碳纳米管催化剂上氧还原过程中的扩散。
Carbon nanotube (CNT)-supported Pt catalysts (Pt/CNT) for use as cathode components in polymer electrolyte fuel cells (PEFCs) were covered with silica layers to prevent particle size increases during operation of the PEFC, either through the sintering of the Pt particles or the dissolution and redeposition of Pt ions. The formation of silica layers by the successive hydrolysis of 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS) significantly improved the durability of the Pt/CNT catalysts under cathodic conditions, although the activity of the silica-coated material for the oxygen reduction reaction was slightly lower than that of the uncoated catalyst. In contrast, a silica-coated Pt/CNT catalyst prepared by the successive hydrolysis of APTES and TEOS in the presence of NH2–(CH2)n–NH2 (n = 6, 8 and 10) exhibited both high catalytic activity and excellent durability. The NH2–(CH2)n–NH2 added during the silica coating process worked as a template for the formation of micropores in the silica layers and the resulting pore structures enhanced the diffusion of both reactants and products during oxygen reduction on the silica-coated Pt/CNT catalysts.