Experimental Determination of the Intrinsic Oxygen Reduction Kinetics on Polycrystalline Platinum and the Role of the Adsorbed Oxygen

Abstract

The Oxygen Reduction Reaction (ORR) is a fundamental reaction in electrochemical devices such as fuel cells and sensors. The ORR only occurs on few catalytically active surfaces, mainly platinum and its alloys and understanding its mechanism is critically important to develop new catalysts and applications. In contrast to the related Hydrogen evolution/oxidation reaction, the intrinsic ORR activity is rarely determined due to simultaneous formation of Pt-O species. Therefore, the ORR activity is measured at a benchmark potential making its susceptible to the measurement characteristics, such as "activation", scan rate, and scan direction.We found that by using a specially designed experimental procedure one can separate the effect of Pt-O on the ORR kinetics without extensive modelling or fitting. As a results an exemplary Pt-O corrected Tafel plot on polycrystalline platinum is displayed in figure 1.In this presentation we will discuss the underlying method, its application on a range of different ORR environments, the nature of the Pt-O species, and the implications for ORR mechanism itself. Figure 1