A first principles study of oxygen reduction reaction on a Pt(111) surface modified by a subsurface transition metal M (M = Ni, Co, or Fe)

Abstract

We have performed first-principle density functional theory calculations to investigate how a subsurface transition metal M (M = Ni, Co, or Fe) affects the energetics and mechanisms of oxygen reduction reaction (ORR) on the outermost Pt mono-surface layer of Pt/M(111) surfaces. In this work, we found that the subsurface Ni, Co, and Fe could down-shift the d-band center of the Pt surface layer and thus weaken the binding of chemical species to the Pt/M(111) surface. Moreover, the subsurface Ni, Co, and Fe could modify the heat of reaction and activation energy of various elementary reactions of ORR on these Pt/M(111) surfaces. Our DFT results revealed that, due to the influence of the subsurface Ni, Co, and Fe, ORR would adopt a hydrogen peroxide dissociation mechanism with an activation energy of 0.15 eV on Pt/Ni(111), 0.17 eV on Pt/Co(111), and 0.16 eV on Pt/Fe(111) surface, respectively, for their rate-determining O2 protonation reaction. In contrast, ORR would follow a peroxyl dissociation mechanism on a pure Pt(111) surface with an activation energy of 0.79 eV for its rate-determining O protonation reaction. Thus, our theoretical study explained why the subsurface Ni, Co, and Fe could lead to multi-fold enhancement in catalytic activity for ORR on the Pt mono-surface layer of Pt/M(111) surfaces.

Theoretical investigation on coadsorption effect of O2 and H2O on Pt(111) surface

“…For H 2 O chemisorption, the results indicated that H 2 O molecule favorably adsorbed at the surface with its O atoms, and the whole molecular plane is nearly parallel to the surface (the O-H bonds tilted at 4.5°), which agrees well with the previous results [14]. Table 1.…”

“…First-principles methods have been widely used to describe and predict significant characteristics of ORR, e.g., the geometrical structure, bonding energy, and energy barrier of elementary reactions [12][13][14][15][16][17][18][19][20][21][22]. Eichler and Hafner [19] studied O 2 adsorption using density functional theory (DFT) calculation and identified superoxide O 2 À as the paramagnetic chemisorbed precursor at the bridge site of Pt ( Ogasawara et al [23] studied the H 2 O-metal interactions using soft X-ray spectroscopy and DFT calculations, and found that the H 2 O molecules in the first layer bind directly to the surface and to each other through the in-layer hydrogen bonds without dissociation.…”

A DFT study of oxygen reduction reaction mechanism over O-doped graphene-supported Pt4, Pt3Fe and Pt3V alloy catalysts

“…In addition, a parallel mechanism that includes both HOO* and HOO*H dissociations has been proposed for ORR on the Pt(111) surface [33]. The H 2 O 2 dissociation has also been suggested to be applicable to the Pt-and Pt-based bimetallic catalysts [22,34]. Furthermore, the composition and morphology of the electrocatalysts, as well as the structure and coverage of the adsorbed oxygen species on the catalyst surface could influence the ORR mechanism [27,31,35].…”

“…The first step of ORR is the chemisorption of O 2 on the surface of the electrocatalyst. The subsequent elementary ORR steps have been summarized into three main ORR mechanisms: (i) O 2 dissociation; (ii) HOO dissociation; and (iii) H 2 O 2 dissociation [22]. The O 2 dissociation mechanism was found in both acidic and alkaline aqueous electrolytes [29].…”

Theoretical investigation of the effect of OH− ions on O2 adsorption on low-index Pt surfaces in alkaline solution

“…Computer simulation provides an alternative method to explore the ORR mechanism and a theoretical supplement for state-of-art experimental techniques. Extensive theoretical studies on the O 2 adsorption and ORR mechanism have been reported [16][17][18][19][20][21][22][23]. However, most of them employed the DFT method, which cannot explicitly consider the effect of bulk solvent and obtain the dynamic information of adsorption interface.…”