A comparison of physically and chemically defective graphene nanosheets as catalyst supports for cubic Pd nanoparticles in an alkaline oxygen reduction reaction

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• 作者：Zhe-Ting Liu ; Kun-Lung Huang ; Yi-Shan Wu ; Yuan-Ping Lyu ; Chien-Liang Lee ; ^{cl_lee@kuas.edu.tw" class="auth_mail" title="E-mail the corresponding author} ; ^{cl_lee@url.com.tw" class="auth_mail" title="E-mail the corresponding author}
• 关键词：support effect ; reduced graphene oxides ; XPS ; XRD ; TEM
• 刊名：Electrochimica Acta
• 出版年：2015
• 出版时间：20 December 2015
• 年：2015
• 卷：186
• 期：Complete
• 页码：552-561
• 全文大小：3183 K

文摘

An electrostatic attraction method is utilized for successfully attaching 10 nm Pd nanocubes on reduced graphene nanosheet (RGN) surfaces. The RGNs used to support the Pd nanocubes are prepared via both a sonoelectrochemical method (RGN_SECM) and a chemical reduction method (RGN_CM). X-ray photoelectron spectroscopic analyses indicate the domination of physical defects and C-OH groups on the surfaces of RGN_SECM and RGN_CM, respectively. The linear scanning voltammograms, taken using rotating ring-disk electrode analyses in alkaline oxidation-reduction reactions (ORRs), show that the Pd nanocubes supported by RGN_SECM (Pd cubes/RGN_SECM) and RGN_CM (Pd cubes/RGN_CM) show improved onset potentials of 0.1 V on the order of Pd cubes/RGN_SECM > Pd cubes/RGN_CM > Pt/C ∼ Pd/C > Pd nanocubes for their catalytic disk currents in the electron-transfer region. Mass-transfer-corrected Tafel diagrams demonstrate that RGN_SECM, which contains a greater number of physical defects, facilitated greater active sites of these Pd nanocubes due to its greater surface area, and thus better promoted ORRs. In terms of the kinetic current density, a greater mass activity (7.85 × 10⁻² mA·μg⁻¹) is observed for the Pd cubes/RGN_SECM composite. Additionally, the durability test reveals that RGN_SECM could provide good strength to stabilize Pd nanocubes during a long ORR period.