Oxygen reduction reaction at three-phase interfaces.
Oxygen reduction reaction at three-phase interfaces.
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DOI：
10.1002/cphc.201000190
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发表时间：
2010-09
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影响因子：
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通讯作者：
Ram Subbaraman;D. Strmčnik;A. Paulikas;V. Stamenković;N. Markovic
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作者：
Ram Subbaraman;D. Strmčnik;A. Paulikas;V. Stamenković;N. Markovic
研究了含金属电解质-钠离子三相界面上氧还原反应的动力学。我们首先证明了Nafion的磺酸阴离子可以吸附在广泛的表面上，从Pt（hkl）单晶表面、Pt-poly、Pt-skin(在Pt（3)Ni（111）表面通过超高真空（UHV）退火产生）到高表面积纳米结构薄膜（NSTF）催化剂。磺酸盐的表面覆盖和Pt-磺酸盐相互作用的强度强烈依赖于Pt表面原子的几何形状和性质。此外，发现它们在这些表面上的行为类似于（bi）硫酸盐阴离子特异性吸附，其中对于Pt（hkl）表面，趋势是Pt(111)>Pt(110)>Pt(100)，对于Pt(3)Ni（111）的Pt-skin表面，发现相互作用强度为Pt-skin<Pt（111）。我们还发现，无论表面取向和/或表面原子的电子性质如何，ORR总是被电极表面离子的存在所抑制，这证实了Nafion不是一种非吸附电解质。最后，应用从研究定义明确的Pt（hkl）表面获得的知识提出，在nafon覆盖的高表面积催化剂上，ORR的失活也由磺酸盐阴离子的特定吸附控制。
The kinetics of the oxygen reduction reaction (ORR) is studied at metal-supporting electrolyte-Nafion three-phase interfaces. We first demonstrate that the sulfonate anions of Nafion are specifically adsorbed on a wide range of surfaces ranging from Pt(hkl) single-crystal surfaces, Pt-poly, Pt-skin [produced on a Pt(3)Ni(111) surface by annealing in ultrahigh vacuum, UHV] to high-surface-area nanostructured thin-film (NSTF) catalysts. The surface coverage by sulfonate and the strength of the Pt-sulfonate interaction are strongly dependent on the geometry and the nature of the Pt surface atoms. Also, they are found to behave analogous to (bi)sulfate anion-specific adsorption on these surfaces, where for the Pt(hkl) surfaces, the trend is Pt(111)>Pt(110)>Pt(100) and for the Pt-skin surface on Pt(3)Ni(111), the interaction strength is found to be Pt-skin<Pt(111). We also found that irrespective of the surface orientation and/or the electronic properties of the surface atoms, the ORR is always inhibited by the presence of ionomers at the electrode surface, confirming that Nafion is not a non-adsorbing electrolyte. Finally, the knowledge gained from studying well-defined Pt(hkl) surfaces is applied to propose that deactivation of the ORR on Nafion-covered high-surface-area catalysts is also controlled by specific adsorption of sulfonate anions.