The Role of SnO2 on Electrocatalytic Activity of PtSn Catalysts

In our previous paper, we described in detail studies of Sn influence on electrocatalytic activity of PtSn catalyst for CO and formic acid oxidation (StevanoviAc et al., J. Phys. Chem. C, 118 (2014) 278-289). The catalyst was composed of a Pt phase, Pt3Sn alloy and very small SnO2 particles. Different electrochemical treatment enabled studies of PtSn/C having Sn both in surface and subsurface layers and skeleton structure of this catalyst with Sn only in subsurface layers. The results obtained revealed the promotional effect of surface Sn whether alloyed or as oxide above all in preventing accumulation of CO and blocking the surface Pt atoms. As a consequence, in formic acid oxidation, the currents are not entering the plateau but increasing constantly until reaching a maximum. It was concluded that at lower potentials the effect of Sn on formic acid oxidation was predominantly electronic but with increasing the potential bi-functional mechanism prevailed due to the leading role of SnO2. This role of SnO2 is restated in the present study. Therefore, CO and formic acid oxidation were examined at PtSnO2/C catalyst. The catalyst was synthesised by the same microwave-assisted polyol procedure. According to XRD analysis, the catalyst is composed of a Pt phase and SnO2 phase. The reactions were examined on PtSnO2/C catalyst treated on the same way as PtSn/C. Comparing the results obtained, the role of SnO2 is confirmed and at the same time the significance of alloyed Sn and its electronic effect is revealed

Methanol electrooxidation in alkaline solutions on platinum-based electrodes: Classical and dynamical approach

The electrochemical oxidation of methanol has been carefully studied due to its application in fuel cells. In this work electrooxidation of methanol was investigated on bare platinum electrode, the platinum electrode covered with Nafion and platinum supported on zeolite 13X. Along with classical electrochemical methods, attractor reconstruction was used to make rough distinction among possible reaction mechanisms on different forms of Pt. The obtained transient voltammogram records were used to calculate apparent rate constants for methanol oxidation limiting steps in transient period. All samples contributed to methanol oxidation by basically same reaction mechanism, but with significantly different apparent rate constants