直接热分解法制备单相Pd-Fe合金催化剂及电催化氧还原活性

doi:10.15541/jim20150213

摘要/Abstract

摘要：

以醋酸钯和醋酸亚铁为前驱体, 采用直接热分解法制备了碳载Pd₃-Fe₁(Pd₃-Fe₁/C)催化剂。用X射线衍射(XRD)、透射电镜(TEM)和X射线光电子能谱(XPS)等技术对催化剂进行了表征, 用循环伏安法和线性扫描伏安法研究了催化剂对氧的电催化还原性能。结果表明, 制备的Pd₃-Fe₁/C复合催化剂具有单相均一的合金结构, Fe进入Pd晶格改变了Pd电子结构和结构常数。电化学数据表明, Pd₃-Fe₁/C对氧还原比Pd/C催化剂有更高的电催化性能。

关键词: 直接热分解, 碳载Pd-Fe催化剂, 单相合金, 氧还原

Abstract:

The Pd₃-Fe₁/C catalyst was synthesized with the direct thermo-decomposition method using Pd(CH₃COO)₂ and Fe(CH₃COO)₂ as precursors. The Pd₃-Fe₁/C catalyst was characterized with X-ray diffraction(XRD), transmission electron microscope(TEM) and X-photoelectron spectroscope(XPS). The electrocatalytic performance of the Pd₃-Fe₁/C catalyst was investigated with the cyclic voltammetry and Linear scan voltammograms．The results show that Fe atom has entered into the Pd crystal lattice and formed a single-phase fcc disordered alloyed structure (solid solution). Electrochemical data indicate that the eletrocatalytic activity of the Pd₃-Fe₁/C electrocatalyst for oxygen reduction reaction (ORR) is much higher than that of Pd/C electrocatalyst.

Key words: direct thermo-decomposition, carbon supported Pt-Fe catalyst, uniform alloy, oxygen reduction

中图分类号:

O646

王彦恩, 武小杰, 何城磊, 赵佳宁, 唐亚文, 陆天虹. 直接热分解法制备单相Pd-Fe合金催化剂及电催化氧还原活性[J]. 无机材料学报, 2015, 30(12): 1315-1320.

WANG Yan-En, WU Xiao-Jie, HE Cheng-Lei, ZHAO Jia-Ning, TANG Ya-Wen, LU Tian-Hong. Carbon Supported Pd-Fe Catalyst with Uniform Alloy Structure Prepared with Direct Thermo-decomposition Method for Oxygen Reduction Reaction[J]. Journal of Inorganic Materials, 2015, 30(12): 1315-1320.

图/表 8

图1 (a)Pd/C和(b)Pd3-Fe1/C催化剂的EDS图谱

Fig. 1 EDS patterns of (a) Pd/C and (b) Pd3-Fe1/C catalysts

图2 (a) Pd/C 和(b) Pd3-Fe1/C催化剂的XRD图谱

Fig. 2 XRD patterns of (a) Pd/C and (b) Pd3-Fe1/C catalysts

表1 Pd/C和Pd3-Fe1/C催化剂的结构参数

Table 1 Structure parameters of Pd/C and Pd3-Fe1/C catalysts

Catalyst	Pd-Pd bond distance/nm	Lattice constant, α/nm	Crystalline size /nm	Atomic fraction of Fe in the Pd₃-Fe₁/C catalyst/%	Atomic fraction of alloying Fe/%	Electrochemical area/ (m²·g^-1)
Pd/C	0.277	0.391	3.51	0	0	44.51
Pd₃-Fe₁/C	0.274	0.387	2.54	25	24.63	52.79

图3 (a) Pd/C (b) Pd3-Fe1/C催化剂中Pd3d的XPS图谱

Fig. 3 Pd3d XPS spectra of (a) Pd/C and (b) Pd3-Fe1/C catalysts

表2 不同形态的Pd的含量及其结合能

Table 2 Binding energy and relative intensities of Pd0 and PdII

Catalyst	Speciation	Binding energy of Pd3d_5/2/eV	Relative intensity/%
Pd/C	Pd⁰	335.26	51.1
Pd/C	Pd^II	336.90	48.9
Pd₃-Fe₁/C	Pd⁰	335.75	73.0
Pd₃-Fe₁/C	Pd^II	337.60	37.0

图4 催化剂样品的HRTEM和TEM照片及EDS能谱图

Fig.4 HRTEM and TEM images of the as-prepared catalysts and the catalysts EDS spectra. (a, b): HRTEM images of (a) Pd/C and (b) Pd3-Fe1/C catalysts; (c): TEM images of the Pd3-Fe1/C catalyst; (d): Overall EDS spectrum of large set of Pd3-Fe1/C particles in (c); (e): EDS spectrum of individual Pd3-Fe1/C particle

图5 (a) Pd/C 和(b)Pd3-Fe1/C 催化剂电极在氮气饱和的 0.5 mol/L HClO4 溶液中的循环伏安曲线

Fig. 5 Cyclic voltammograms of (a) Pd/C and (b) Pd3-Fe1/C catalyst electrodes in 0.5 mol/L HClO4 solution

图6 (a) Pd/C和(b) Pd3-Fe1/C催化剂电极在氧气饱和的 0.5 mol/L HClO4 溶液中的线性扫描伏安曲线

Fig. 6 Linear sweep voltammograms of (a) Pd/C and (b) Pd3- Fe1/C catalyst electrodes in 0.5 mol/L HClO4 solution with saturated oxygen. Scan rate: 5 mV/s, Rotating speed: 2000 r/min

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