Pd@Pt Core鈥揝hell Concave Decahedra: A Class of Catalysts for the Oxygen Reduction Reaction with Enhanced Activity and Durability

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• 作者：Xue Wang ; Madeline Vara ; Ming Luo ; Hongwen Huang ; Aleksey Ruditskiy ; Jinho Park ; Shixiong Bao ; Jingyue Liu ; Jane Howe ; Miaofang Chi ; Zhaoxiong Xie ; Younan Xia
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：December 2, 2015
• 年：2015
• 卷：137
• 期：47
• 页码：15036-15042
• 全文大小：472K
• ISSN：1520-5126

文摘

We report a facile synthesis of multiply twinned Pd@Pt core鈥搒hell concave decahedra by controlling the deposition of Pt on preformed Pd decahedral seeds. The Pt atoms are initially deposited on the vertices of a decahedral seed, followed by surface diffusion to other regions along the edges/ridges and then across the faces. Different from the coating of a Pd icosahedral seed, the Pt atoms prefer to stay at the vertices and edges/ridges of a decahedral seed even when the deposition is conducted at 200 掳C, naturally generating a core鈥搒hell structure covered by concave facets. The nonuniformity in the Pt coating can be attributed to the presence of twin boundaries at the vertices, as well as the {100} facets and twin defects along the edges/ridges of a decahedron, effectively trapping the Pt adatoms at these high-energy sites. As compared to a commercial Pt/C catalyst, the Pd@Pt concave decahedra show substantial enhancement in both catalytic activity and durability toward the oxygen reduction reaction (ORR). For the concave decahedra with 29.6% Pt by weight, their specific (1.66 mA/cm²_Pt) and mass (1.60 A/mg_Pt) ORR activities are enhanced by 4.4 and 6.6 times relative to those of the Pt/C catalyst (0.36 mA/cm²_Pt and 0.32 A/mg_Pt, respectively). After 10鈥?00 cycles of accelerated durability test, the concave decahedra still exhibit a mass activity of 0.69 A/mg_Pt, more than twice that of the pristine Pt/C catalyst.