Electrochemical Energy Laboratory, Materials Science and Engineering Program, The University of Texas at Austin, Austin, Texas 78712, USA.
Langmuir. 2010 Feb 16;26(4):2894-903. doi: 10.1021/la902756j.
Pt-encapsulated Pd(x)Co(100-x) nanoalloy electrocatalysts supported on carbon have been synthesized by a rapid microwave-assisted solvothermal (MW-ST) method within 15 min at as low as 300 degrees C. Subsequently, the samples have been heat treated at 900 degrees C in a reducing gas atmosphere to obtain Pt-Pd-Co nanoalloys. X-ray diffraction (XRD) analysis of the as-synthesized and 900 degrees C heat-treated samples reveals interesting changes in phase compositions and degree of alloying with Co and Pt contents and heat treatment. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) data of the as-synthesized samples confirm Pt enrichment on the surface of the Pd-Co nanoparticles. Rotating disk electrode (RDE) and single cell proton exchange membrane fuel cell measurements reveal that the as-synthesized Pt-encapsulated Pd(80)Co(20) (i.e., 75 wt % Pd(80)Co(20) + 25 wt % Pt) with 20 wt % total metal loading on carbon or 5 wt % Pt exhibit higher catalytic activity for the oxygen reduction reaction (ORR) compared to Pt with 20 wt % Pt loading on carbon. Significant changes in the catalytic activity for ORR occur on heat treatment at 900 degrees C as a result of changes in the phase composition and increase in particle size. This study demonstrates that the encapsulation of Pd-Co alloys with Pt offers a significant enhancement in activity for ORR per unit mass of Pt, offering a significant cost savings.
通过快速微波辅助溶剂热（MW-ST）方法，在 300°C 以下仅 15 分钟即可合成负载在碳上的 Pt 封装 Pd(x)Co(100-x)纳米合金电催化剂。随后，将样品在还原气氛中于 900°C 下进行热处理，以获得 Pt-Pd-Co 纳米合金。对合成的和 900°C 热处理的样品进行 X 射线衍射（XRD）分析，揭示了随着 Co 和 Pt 含量以及热处理的变化，相组成和合金化程度的有趣变化。合成样品的透射电子显微镜（TEM）和 X 射线光电子能谱（XPS）数据证实了 Pt 在 Pd-Co 纳米颗粒表面的富集。旋转圆盘电极（RDE）和单电池质子交换膜燃料电池测量表明，与负载 20wt%Pt 的碳相比，负载 20wt%总金属（即 75wt%Pd(80)Co(20) + 25wt%Pt）或负载 5wt%Pt 的合成的 Pt 封装 Pd(80)Co(20)（即 75wt%Pd(80)Co(20) + 25wt%Pt）对氧还原反应（ORR）具有更高的催化活性。由于相组成的变化和粒径的增加，900°C 热处理会导致 ORR 催化活性发生显著变化。这项研究表明，用 Pt 封装 Pd-Co 合金可以显著提高单位质量 Pt 的 ORR 活性，从而显著降低成本。
