Electrocatalyst supports stable to high potential are required for the proton exchange membrane fuel cell cathode. Electrocatalyst supports based on tantalum doped tin oxide (Ta: SnO2) were prepared by electrospinning. The dopant amount was varied between 0 (undoped SnO2, TO) and 7.5 at.%, and the resulting materials were characterized for their morphology, composition, structure, porosity and electrical properties. Platinum nanoparticles prepared by a microwave assisted polyol method were deposited with different loadings on 1 at.% Ta doped SnO2 (1Ta:SnO2), selected for its highest electrical conductivity of 0.09 S cm -1 . Their electrocatalytic properties towards the oxygen reduction reaction (ORR) were compared with those of the same S2 particles deposited on carbon black and those of a commercial carbon supported Pt catalyst.Pt/1Ta:SnO2 showed higher ORR activity and stability at high potential than Pt/C. In particular, the electrocatalyst with the lowest Pt loading (7 wt%) presented high mass activity and stability which, from XPS analysis, is suggested to result from very strong metal support interaction. These results indicate that amongst tin oxides doped with pentavalent metals such as niobium (Nb:SnO2), antimony (Sb:SnO2) and tantalum, Ta:SnO2 has the advantage of both higher conductivity than Nb:SnO2, and greater stability in the fuel cell voltage range than Sb:SnO2.

Platinum is the most employed electrocatalyst for the reactions taking place in energy converters, such as the oxygen reduction reaction in proton exchange membrane fuel cells, despite being a very low abundant element in the earth’s crust and thus extremely expensive. The search for more active electrocatalysts with ultra-low Pt loading is thus a very active field of investigation. Here, surface-limited redox replacement (SLRR) that utilizes the monolayer-limited nature of underpotential deposition (UPD) was used to prepare ultrathin deposits of Pt, using Te as sacrificial metal. Cyclic voltammetry and anodic potentiodynamic scanning experiments have been performed to determine the optimal deposition conditions. Physicochemical and electrochemical characterization of the deposited Pt was carried out. The deposit comprises a series of contiguous Pt islands that form along the grain interfaces of the Au substrate. The electrochemical surface area (ECSA) of the Pt deposit obtained after 5 replacements, estimated to be 18 m2/g, is in agreement with the ECSA of extended surface catalysts on flat surfaces.