Platinum–tin bimetallic nanoparticles for methanol tolerant oxygen-reduction activity
Platinum–tin bimetallic nanoparticles for methanol tolerant oxygen-reduction activity
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DOI：
10.1016/j.electacta.2008.07.053
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发表时间：
2008-12
影响因子：
6.6
通讯作者：
C. Jeyabharathi;P. Venkateshkumar;J. Mathiyarasu;K. Phani
中科院分区：
文献类型：
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作者：
C. Jeyabharathi;P. Venkateshkumar;J. Mathiyarasu;K. Phani
以乙二醇为还原剂，通过简单的金属前驱体还原制备了碳载Pt-Sn/C_xO纳米粒子电催化剂。在氩气气氛下热处理催化剂以改善铂与锡的合金化。所制备的Pt-Sn纳米颗粒表现出单相的Pt的fcc结构和热处理导致fcc的Pt 75 Sn 25相和六方合金结构的Pt 50 Sn 50相。所制备的Pt-Sn/C催化剂的透射电子显微镜图像显示平均粒径为约100 nm。5.8nm，粒径分布相对较窄，粒径增大至约1.5nm。当在500°C下热处理时，由于附聚，20 nm。采用旋转环盘电极技术（流体动力学伏安法）评价其对氧还原的电催化活性，结果表明：Pt-Sn/C（制备态）>Pt-Sn/C（250°C）>Pt-Sn/C（500°C）> Pt-Sn/C（600°C）> Pt-Sn/C（800°C）。动力学分析表明，Pt-Sn/C催化剂上的氧还原反应遵循四电子过程，生成水。此外，Pt-Sn/C催化剂在氧还原反应期间表现出比Pt/C催化剂高得多的甲醇耐受性，评估本发明的Pt-Sn/C催化剂可以用作直接甲醇燃料电池中的甲醇耐受性阴极催化剂。
Carbon-supported Pt–Sn/C bimetallic nanoparticle electrocatalysts were prepared by the simple reduction of the metal precursors using ethylene glycol. The catalysts heat-treated under argon atmosphere to improve alloying of platinum with tin. As-prepared Pt–Sn bimetallic nanoparticles exhibit a single-phase fcc structure of Pt and heat-treatment leading to fcc Pt75Sn25phase and hexagonal alloy structure of the Pt50Sn50phase. Transmission electron microscopy image of the as-prepared Pt–Sn/C catalyst reveals a mean particle diameter of ca. 5.8nm with a relatively narrow size distribution and the particle size increased to ca. 20nm when heat-treated at 500°C due to agglomeration. The electrocatalytic activity of oxygen reduction assessed using rotating ring disk electrode technique (hydrodynamic voltammetry) indicated the order of electrocatalytic activity to be: Pt–Sn/C (as-prepared)>Pt–Sn/C (250°C)>Pt–Sn/C (500°C)>Pt–Sn/C (600°C)>Pt–Sn/C (800°C). Kinetic analysis reveals that the oxygen reduction reaction on Pt–Sn/C catalysts follows a four-electron process leading to water. Moreover, the Pt–Sn/C catalyst exhibited much higher methanol tolerance during the oxygen reduction reaction than the Pt/C catalyst, assessing that the present Pt–Sn/C bimetallic catalyst may function as a methanol-tolerant cathode catalyst in a direct methanol fuel cell.