Stability limits of tin-based electrocatalyst supports

Tin-based oxides are attractive catalyst support materials considered for application in fuel cells and electrolysers. If properly doped, these oxides are relatively good conductors, assuring that ohmic drop in real applications is minimal. Corrosion of dopants, however, will lead to severe performance deterioration. The present work aims to investigate the potential dependent dissolution rates of indium tin oxide (ITO), fluorine doped tin oxide (FTO) and antimony doped tin oxide (ATO) in the broad potential window ranging from -0.6 to 3.2 V-RHE in 0.1 M H2SO4 electrolyte. It is shown that in the cathodic part of the studied potential window all oxides dissolve during the electrochemical reduction of the oxide - cathodic dissolution. In case an oxidation potential is applied to the reduced electrode, metal oxidation is accompanied with additional dissolution - anodic dissolution. Additional dissolution is observed during the oxygen evolution reaction. FTO withstands anodic conditions best, while little and strong dissolution is observed for ATO and ITO, respectively. In discussion of possible corrosion mechanisms, obtained dissolution onset potentials are correlated with existing thermodynamic data.