Oxygen reduction reaction at Pt single crystals: a critical overview

Abstract

Oxygen reduction reaction (ORR) dynamics at platinum single crystal surfaces is reviewed, and experimental results in acid and alkaline solutions are discussed in the framework of theoretical studies.Special emphasis is devoted to point out the role of the surface charge, water structure and adsorbed oxygen containing species. Additionally, discussion about the possible relevance of hydrogen peroxide as an intermediate species is also included. It is shown that the ORR is a complex process affected by many different factors and so neither surface charge nor oxygen-containing species coverage alone are a determining factor of the electrode activity. Instead, adlayer structures and the relation between adsorbed water, H 2 O ads , water dissociation products, OH ads or O ads , and PtO oxide species coverage affect the whole energetics of the adsorption processes and may determine the surface reactivity. Finally, if H 2 O 2 is an intermediate product in the ORR mechanism, it would be crucial to find a suitable catalyst able to effectively reduce H 2 O 2 at high potentials and inhibit its oxidation.

Oxygen reduction on nanostructured platinum surfaces in acidic media: Promoting effect of surface steps and ideal response of Pt(1 1 1)

“…As explained elsewhere, ohmic corrections, iR u , were not necessary under our experimental conditions [32]. The exact magnitude of iR u depends on several factors: the electrode shapes, the potential profile in the cell, cell geometry, solution conductance.…”

MOF-reduced Graphene Oxide Composites with Enhanced Electrocatalytic Activity for Oxygen Reduction Reaction

“…A good linearity of the plots and near parallelism of the fitting lines at various potentials were observed, suggesting that the reactions on Co@Co 3 O 4 -rGO are first-order over the potential range. To assess the ORR property of the catalysts fairly, the preferred electron transfer number should four [29]. As we obtained from the Koutechy-Levich calculation, the electron transfer number on Co@Co 3 O 4 -rGO…”

Rational Design and Synthesis of Low-Temperature Fuel Cell Electrocatalysts

“…In the context of ORR, several types of model surfaces have been developed, including Pt single-crystal electrodes [46,[49][50][51], Pt skin surfaces [8], Pt monolayers [52,53], and near-surface alloys [54]. Through results obtained using these surfaces, researchers have gained important insights into ORR: (1) kinetics of ORR is sensitive to atomic arrangements, (2) composition of the topmost surface atomic layer can greatly affect ORR kinetics, and (3) chemical properties of the surface can be tuned by strain and ligand effects.…”