Ab Initio Study of Thin Oxide–Metal Overlayers as an Inverse Catalytic System for Dioxygen Reduction and Enhanced CO Tolerance

Abstract

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 O 2 in the form of a superoxo or peroxo. On the other hand, the thin MgO overlayer readily prevents the π-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−metal overlayer structure can yield a sharply tuned free energy profile for ORR.

Noble metal supported hexagonal boron nitride for the oxygen reduction reaction: a DFT study

“…However, its ORR catalytic activity can be signicantly improved by surfactant exfoliation, hetero-atom or metal doping, and deposition on metal supports. [18][19][20][21][22][23][24][25][26] Gao et al investigated the role of different defects for Cu supported BN and found that a boron vacancy helps in binding ORR intermediates more strongly. 27 On the other hand, h-BN exhibits other unique properties such as high stability which is favorable for the ORR.…”

Structural and Electronic Descriptors of Catalytic Activity of Graphene‐Based Materials: First‐Principles Theoretical Analysis

“…The steps to estimate reaction free energies and adsorption free energies of intermediates are given in the Supporting Information . The Δ G OH is an efficient quantifying parameter of catalytic activity, as a plot of Δ G OH versus overpotential yields a volcano‐type relationship, from which the optimal binding strength of OH can be identified .…”

Interfacial Chemistry of Low‐Dimensional Systems for Applications in Nanocatalysis

“…Quite recently, some works suggested that this electron tunneling concept could be active in the case of electrochemical reactions. DFT calculations performed on MgO(100) ultrathin films supported on Ag(100) suggested the existence of electron tunneling through the oxide toward some key intermediates involved in the oxygen reduction reaction (ORR), resulting in a system with activity comparable with Pt. The exploitation of electron tunneling in electrocatalysis seems to be quite general; for example other authors suggested that the adsorption energy of hydrogen, a key descriptor in the hydrogen evolution reaction, on the surface of monolayer MoS 2 is dictated by the value of the work function of the supporting metal …”