Hydrogen Interaction (Electrosorption and Evolution) Characteristics of Pd and Pd₃Co Alloy Nanoparticles: An In-situ Investigation with Electrochemical Impedance Spectroscopy

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• 作者：Ramesh Kumar Singh ; Rahul Ramesh ; Ruttala Devivaraprasad ; Arup Chakraborty ; Manoj Neergat ; ^{nmanoj@iitb.ac.in" class="auth_mail" title="E-mail the corresponding author} ; ^{manojneergat@gmail.com" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Pd-based nanoparticles ; electrochemical impedance spectroscopy ; hydrogen evolution reaction ; OPD ; UPD
• 刊名：Electrochimica Acta
• 出版年：2016
• 出版时间：10 March 2016
• 年：2016
• 卷：194
• 期：Complete
• 页码：199-210
• 全文大小：1137 K

文摘

Electrochemical impedance spectroscopy (EIS) and voltammetry are used to investigate the interaction of hydrogen with Pd and Pd₃Co nanoparticles supported on a carbon-matrix. The EIS patterns are recorded in the hydrogen underpotential deposition (UPD) and overpotential deposition (OPD) regions of the voltammogram in acidic electrolyte (0.1 M HClO₄) where the hydrogen interacts with palladium. The atomic ratio of hydrogen to Pd (n_(H/Pd)) estimated from the H_upd region of the voltammogram of Pd nanoparticles suggests a gradual α-β transition unlike the sharp transition reported with bulk Pd thin-films. However, a potential range of this transition can be estimated from the EIS patterns. The diffusion characteristics of hydrogen in the Pd lattice are absent in the EIS patterns (at mid-frequency region) of these nanoparticles due to the very small particle size. The kinetic parameters, those effectively describe the Pd-H system, are estimated from the complex non-linear least square (CNLS) fit of the EIS patterns. A maximum in the charge-transfer resistance with potential, similar to that reported with bulk Pd thin-films, is observed with both Pd and Pd₃Co nanoparticles suggesting the trapping mechanism of hydrogen.