High oxygen reduction reaction activity and durability of Pt catalyst photo-deposited on SnO₂-coated and uncoated multi-walled carbon nanotubes

Platinum nanoparticles were photo-deposited on acid-treated multi-walled carbon nanotubes (CNTs) and SnO₂-coated CNTs. The SnO₂-CNT nanocomposite was synthesised by a chemical method. Scanning and scanning transmission electron microscopy results indicated that the CNTs surface is partially covered by the SnO₂ layer. The surface morphology of the Pt catalyst depends on the nature of the support material. For instance, porous Pt aggregates of various sizes are formed at specific nucleation sites on the CNT surface, while a selective deposition of Pt was observed on the metal oxide part of the SnO₂-CNT. Cyclic voltammetry and CO stripping investigations in 0.1 M HClO₄ solution confirmed different surface electrochemistry of the Pt catalysts. It is revealed that photo-deposition induces the formation of Pt-Sn nanoalloys due to increased interaction at the oxide interfaces. Both Pt/CNT and Pt/SnO₂-CNT catalysts showed remarkable activity towards the electroreduction of oxygen in acid media. Durability measurement showed that photo-deposited Pt nanoparticles are more resistant to degradation. The corrosion-resistant nature of the SnO₂-CNT support further improves the catalysts stability. Pt/CNT and Pt/SnO₂-CNT catalysts retained 86% and 88% of the initial surface area respectively, after 10,000 potential cycles between 0.6 and 1.2 V_RHE.