Researchers employed synchrotron-based X-ray absorption spectroscopy (XAS) at CHESS to investigate the synergistic interaction of bimetallic Co1.5Mn1.5O4/C catalysts… under real-time operando electrochemical conditions.
Identifying the catalytically active site(s) in the oxygen reduction reaction (ORR) is critical to the development of fuel cells and other technologies. Researchers employed synchrotron-based X-ray absorption spectroscopy (XAS) at CHESS to investigate the synergistic interaction of bimetallic Co1.5Mn1.5O4/C catalysts – which exhibit impressive ORR activity in alkaline fuel cells – under real-time operando electrochemical conditions. Under steady state conditions, both Mn and Co valences decreased at lower potentials, indicating the conversion from Mn-(III,IV) and Co(III) to Mn(II,III) and Co(II), respectively. Changes in the Co and Mn valence states are simultaneous and exhibited periodic patterns that tracked the cyclic potential sweeps.
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Image: Schematic of the in situ XAS electrochemical cell. Working electrode (WE, catalyst on carbon paper) and counter electrode (CE, carbon rod) were immersed in 1 M KOH solution. The reference electrode was connected to the cell by a salt bridge to minimize IR drops caused by the resistance in the thin electrolyte layer within the X-ray window.