Oxidation triggered atomic restructures enhancing the electrooxidation activities of carbon supported platinum–ruthenium catalysts

This study demonstrated that the methanol oxidation reaction (MOR) activity of carbon supported platinum–ruthenium catalysts (Pt–Ru/C) could be enhanced 2.6-fold with adequate oxidation treatment. Our results show that such enhancement is triggered by the hetero-junction of Pt atomic layers on a tetragonal phased RuO2 crystal. In a freshly prepared sample, the nanocatalysts (NCs) were built on a Ru rich core capped by a PtRu alloy shell. The thermal treatment restructures the Pt and Ru atoms to form an ordered heterojunction at the core–shell interface and optimize the activity of the NCs at a temperature of 520 K. The higher temperature oxidizes the Ru into a crystallite rutile RuO2 phase. In such cases the Pt atoms were segregated to form individual crystallites by a substantial lattice mismatch between the metallic Pt and RuO2 phases. This work presents a systematic analysis with theoretical modelling and quantitative characterization, manipulating the structural evolution and thus optimizing the MOR activity of Pt–Ru/C catalysts.