Enhanced Electrocatalysis of Oxygen Reduction on Pt/TaOx/GC

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• 作者：Zaenal Awaludin ; Masatoshi Suzuki ; Jahangir Masud ; Takeyoshi Okajima ; Takeo Ohsaka
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：December 29, 2011
• 年：2011
• 卷：115
• 期：51
• 页码：25557-25567
• 全文大小：1170K
• 年卷期：v.115,no.51(December 29, 2011)
• ISSN：1932-7455

文摘

Here we demonstrate a remarkable enhancement of oxygen reduction reaction (ORR) activity on a novel Pt/TaO_x/GC electrocatalyst where at first tantalum oxide (TaO_x) and next Pt were deposited electrochemically on a glassy carbon (GC) surface. An excellent electrocatalytic activity of the Pt/TaO_x/GC electrocatalyst for ORR was found to be more than 12 times that of the unmodified Pt/GC one as evaluated from the kinetic currents at 0.80 V. SEM images showed no significant differences in the size and distribution of Pt nanoparticles between these two electrocatalysts, indicating that these are not factors causing the observed ORR activity. The spillover of oxygen-containing species resulting from the electronic interaction between Pt and TaO_x, which is evidently demonstrated from the XPS analysis, is strongly suggested as the crucial factor for the ORR enhancement. Interestingly, the spillover effect also results in a remarkable increase in the electrochemically active 鈥渁pparent鈥?surface area of Pt on the Pt/TaO_x/GC electrocatalyst. Moreover, the rotating ring-disk electrode voltammetric measurements obviously showed the increase in limiting current as well as the decrease in ring current on this novel electrocatalyst relative to the unmodified one, confirming a complete four-electron reduction pathway. On the basis of these findings a plausible mechanism has been proposed for the observed enhancement in ORR where the role of TaO_x is to reduce the formation of OH on the Pt surface by spillover effect and to promote d orbital vacancy of Pt for oxygen adsorption by electron donation to Ta.