Electrosynthesis of Co/PPy nanocomposites for ORR electrocatalysis: a study based on quasi-in situ X-ray absorption, fluorescence and in situ Raman spectroscopy

• PPy/Co nanocomposites are synthetized by potentiostatic pulsed electrodeposition.
• We follow in detail the polymerization, the PPy doping/dedoping processes and Co insertion by in-situ Raman Spectroscopy.
• XRF mapping reveals a strong correlation between Co distribution and local current-density.
• Co-nucleation of PPy and Co is evidenced by correlation of Co and N XRF maps.
• The co-location of O and Co in XRF maps indicates that cobalt in the formed composite is present in oxidized state.

Cobalt/polypyrrole ORR electrocatalysts has been electrochemically synthesized by a potentiostatic anodic/cathodic pulse-plating procedure. The deposition electrochemistry has been studied by cyclic voltammetry and in-situ Micro Raman Spectroscopy complemented with scanning X-ray microscopy and micro-spot X-ray absorption spectroscopy (μ-XAS). Linear sweep voltammetry (LSV) under oxygen reduction has been used to assess the electrocatalytic effect of as-electrodeposited Co/PPy. The obtained results have provided new information about the concomitant electropolymerisation and metal incorporation processes occurring under different pulsed co-electrodeposition conditions, important for optimising the electrosynthesis procedure. The colocation of O and Co, evidenced by the O and Co XRF maps indicates that the Co in the formed composite is in oxidized state and for composites formed at low currents using shorter Co pulses coexistence of both CoO and Co3O4 is evidenced by the Co L3 XAS spectra. Bimodal Co distribution as micro-grains on a background of nano-grains and co-nulcleation of PPy and Co is evidenced by correlation of Co and N XRF maps.

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