Ab Initio Study of Thin Oxide鈥揗etal Overlayers as an Inverse Catalytic System for Dioxygen Reduction and Enhanced CO Tolerance
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- 作者：Dongbin Shin ; S. Sinthika ; Min Choi ; Ranjit Thapa ; Noejung Park
- 刊名：ACS Catalysis
- 出版年：2014
- 出版时间：November 7, 2014
- 年：2014
- 卷：4
- 期：11
- 页码：4074-4080
- 全文大小：406K
- ISSN：2155-5435
文摘
Using first-principles density functional theory calculations, we used a thin oxide overlayer, such as MgO, on a metal surface as an inverse catalyst for dioxygen reduction. Surface distortions in the oxide layer, combined with the tunneling of electron from the underneath metal, activated the adsorbed O2 in the form of a superoxo or peroxo. On the other hand, the thin MgO overlayer readily prevents the 蟺-back-bonding between CO and the metal surface, thereby efficiently mitigating the affinity of the metal surface for CO. The operating potential and overpotential for the oxygen reduction reaction (ORR) process have been estimated for various combinations of thin insulators and metals. The strongest binding intermediate in the overall reaction pathway influenced the overpotential. We show that for a Ag(100)-supported MgO surface, the ORR commences with a low overpotential, which is comparable to that of the Pt(111) surface. This suggests that an optimally chosen insulator鈥搈etal overlayer structure can yield a sharply tuned free energy profile for ORR.