Department of Chemistry
Synthesis and Characterization of n-alkylamine-stabilized palladium nanoparticles for electrochemical oxidation of methane
Palladium nanoparticles (PdNPs) have been synthesized using n-alkylamines (Cn-NH2) as stabilizing ligands. The NP size and distribution were controlled by varying the initial mole ratio of PdCl 2/Cn-NH2 and carbon chain lengths of C n-NH2 including hexylamine (C6-NH2), dodecylamine (C12-NH2), and octadecylamine (C 18-NH2). The average PdNP sizes were 20 ± 2.0, 6.0 ± 0.8, 5.6 ± 0.8, 6.5 ± 0.9, and 5.2 ± 0.8 nm prepared with 1:7 PdCl2/C6-NH2, 1:7 PdC l2/C12-NH2, 1:7 PdCl2/C 18-NH2, 1:5 PdCl2/C18-NH 2, and 1:9 PdCl2/C18-NH2, respectively. The particle size decreased with the increase in the carbon chain length of Cn-NH2. The as-synthesized n-alkylamine stabilized PdNPs (Cn-NH2-PdNPs) were fully characterized by transmission electron microscopy, X-ray powder diffraction, Uv-visible absorption spectroscopy, infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), proton nuclear magnetic resonance (1H NMR) spectroscopy, thermogravimetric analysis, graphite furnace atomic absorption spectrometry, and mass spectrometry. The interaction of C18-NH 2 with PdNPs was verified by IR, XPS, and 1H NMR spectra, demonstrating that the amine functionalities were successfully linked to the Pd core surfaces. The PdNPs are soluble and stable in apolar solvents such as benzene, chloroform, n-hexane, and toluene. The electrochemical reactions between CH4 and Cn-NH2-PdNPs on Pd electrodes were studied by cyclic voltammetry and chronoamperometry. These PdNPs reacted readily and produced good response to CH4 at ambient conditions. The sensitivity to CH4 depends on the PdNPs prepared from various n-alkyl chain lengths of Cn-NH2 and also the mole ratio of PdCl2/Cn-NH2. It was determined that PdNPs synthesized from 1:7 PdCl2/C18-NH2 displayed the best electrocatalytic oxidization of CH4. The C18-NH 2-PdNP (5.6 nm) modified Pd electrode could be used repeatedly and had a stable and reproducible response to CH4. © 2010 American Chemical Society.
Source Publication Title
Journal of Physical Chemistry C
American Chemical Society
Li, Zhongping, Jie Gao, Xiaoting Xing, Suozhu Wu, Shaomin Shuang, Chuan Dong, Man Chin Paau, and Martin M.F. Choi. "Synthesis and Characterization of n-alkylamine-stabilized palladium nanoparticles for electrochemical oxidation of methane." Journal of Physical Chemistry C 114.2 (2010): 723-733.