用于燃料电池中氧还原反应的 Pt 封装 Pd-Co 纳米合金电催化剂。

Pt-encapsulated Pd-Co nanoalloy electrocatalysts for oxygen reduction reaction in fuel cells.

机构信息

Electrochemical Energy Laboratory, Materials Science and Engineering Program, The University of Texas at Austin, Austin, Texas 78712, USA.

出版信息

Langmuir. 2010 Feb 16;26(4):2894-903. doi: 10.1021/la902756j.

DOI:10.1021/la902756j

PMID:20141217

Abstract

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.

摘要

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。