ORR stability of Mn–Co/polypyrrole nanocomposite electrocatalysts studied by quasi in-situ identical-location photoelectron microspectroscopy

• One-pot electrosynthesis of Mn–Co/PPy ORR catalyst followed by pyrolysis is used.
• Addition of Co significantly mitigates the effects of ORR aging on Mn/PPy.
• Morphology and core structure (spinel MnCo2O4) of Mn–Co grains are ORR stable.
• ORR effects are confined to a 3–5 nm thick amorphous layer on the Mn–Co grain.
• Quasi in situ single-grain SPEM reveals the Mn/Co chemical changes of this layer.
• The results correlate with a dissolution/redeposition mechanism of metal oxides.

The stability of pyrolyzed Mn–Co/polypyrrole (PPy) nanocomposites towards the Oxygen Reduction Reaction (ORR) in alkaline solution, was studied with a close-knit group of complementary microscopic and space-resolved spectroscopic approaches: Atomic Force Microscopy (AFM), Scanning and High-Resolution Transmission Electron Microscopy (SEM, HRTEM) and identical-location Scanning PhotoElectron Microscopy (SPEM). Tracking quasi-in situ the morphochemical evolution of the Mn–Co/PPy catalyst upon electrochemical aging under ORR conditions by this multi-technique approach, has allowed to clarify the key physico-chemical processes underlying the dramatic impact of Co additions to stability improvement.

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