Microkinetic Modeling of the Oxygen Reduction Reaction at the Pt(111)/Gas Interface

Abstract

A microkinetic model of the oxygen reduction reaction (ORR) on Pt(111) under a gaseous H 2 and O 2 atmosphere is used to predict and explain which compositions of H 2 and O 2 lead to the fastest rate of water formation for temperatures between 600 and 900 K. For a stoichiometric (2:1) mixture of H 2 and O 2 the rate-determing step is found to transition from O H hydrogenation to O 2 H dissociation over this same temperature range. These results are explained in terms of the temperature dependence of the surface coverages of O H and H H and are shown to be consistent with kinetic models aimed at understanding the ORR under electrochemical conditions.

Hydrogen peroxide and oxygen reduction studies on Pt stepped surfaces: Surface charge effects and mechanistic consequences

“…During the last 20 years, a high number of theoretical works have been published in which different ORR mechanisms are proposed [5][6][7][8][9][10][11][12][13][14]. However, it has not been possible to certainly establish the identity of the intermediate species in the different conditions.…”

Detection of Superoxide Anion Oxygen Reduction Reaction Intermediate on Pt(111) by Infrared Reflection Absorption Spectroscopy in Neutral pH Conditions

“…The ORR is a complex electrochemical reaction than requires the transfer of four electrons to yield water as the final product. As a consequence, several different intermediates can take part in the mechanism of the ORR, such as O ads , OH ads , HO 2,ads /HO 2 • , O 2,ads – /O 2 – , H 2 O 2,ads /H 2 O 2 or HO 2 – /HO 2,ads − . The high number of previous computational and experimental studies about the ORR evidence that the reaction occurs through a set of parallel reactions with a similar rate.…”

“…As a consequence, several different intermediates can take part in the mechanism of the ORR, such as O ads , OH ads , HO 2,ads /HO − . 3 The high number of previous computational and experimental studies about the ORR evidence that the reaction occurs through a set of parallel reactions with a similar rate. Within this reaction mechanism, small changes in the experimental conditions could modify the relative rates of the different parallel steps, giving rise to a significant change in the global reaction mechanism.…”

Oxygen reduction reaction (orr) on bimetallic AuPt and AuPd(1 0 0)–electrodes: Effects of the heteroatomic junction on the reaction paths

“…Oxygen reaction mechanisms have been deeply studied for various electrocatalysts and are well documented [74]. As described above, due to the complexity of the reaction, several mechanisms have been proposed and many approaches can be found in the literature [75]; but to the best of our knowledge, there are still some aspects of the reaction which remain unclear. Therefore, as a starting point, we have considered the two steps mentioned previously (2 and 7): the dissociation (or bond breaking) of O 2(ad) and OOH (ad) on pure 1 and mixed surfaces: Pd(100), Pt(100), Au(100), 1Pd/2Au, 2Pd/1Au, 1Pt/2Au and 2Pt/1Au; to investigate the fundamental aspects related with the existence of a bimetallic junction and its influence on the kinetics of the bond breaking of O-O and O-OH to avoid the secondary product (H 2 O 2 ).…”