Promotion of Pt surfaces for ethanol electro-oxidation by the addition of small SnO₂ nanoparticles: Activity and mechanism

The catalytic effect of a SnO₂ co-catalyst for ethanol electrooxidation on polycrystalline Pt is studied by electrochemical methods, in situ infrared reflection-absorption spectroscopy, and high resolution transmission electron microscopy. The electrochemical results show that deposition of small SnO₂ NPs onto the pc-Pt electrode surface significantly enhances the catalytic performance of Pt. Infrared spectroscopy measurements show the effect that small SnO₂ particles have on the removal of CO from the Pt surface and suggest that the electrocatalytic C-C bond splitting activity of Pt, the key step in full conversion of ethanol to CO₂, is not affected by the addition of the -OH species provided by the SnO₂ particles. Also, it is shown that controlled deposition of SnO₂ is needed in order to control the rate of partial oxidation to acetic acid compared to full oxidation to CO₂. The combined results provide new insight into the role of SnO₂ co-catalysts in promoting the electro-oxidation of ethanol to CO₂ on Pt surfaces.