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Publication - Professor David Fermin

    Mean Intrinsic Activity of Single Mn Sites at LaMnO3 Nanoparticles Towards the Oxygen Reduction Reaction


    Celorrio, V, Calvillo, L, van den Bosch, C, Granozzi, G, Aguadero, A, Russell, A & Fermin, D, 2018, ‘Mean Intrinsic Activity of Single Mn Sites at LaMnO3 Nanoparticles Towards the Oxygen Reduction Reaction’. ChemElectroChem, vol 5., pp. 3044-3051


    LaMnO3 has been identified as one of the most active systems
    towards the 4‐electron oxygen reduction reaction (ORR) under alkaline
    conditions, although the rationale for its high activity in comparison
    to other perovskites remains to be fully understood. LaMnO3
    oxide nanoparticles are synthesised by an ionic‐liquid based method over
    a temperature range of 600 to 950 °C. This work describes a systematic
    study of the LaMnO3 properties, from bulk to the outermost
    surface layers, as a function of the synthesis temperature to relate
    them to the ORR activity. The bulk and surface composition of the
    particles are characterised by transmission electron microscopy, X‐ray
    diffraction, X‐ray absorption and X‐ray photoemission spectroscopy
    (XPS), as well as low‐energy ion scattering spectroscopy (LEIS). The
    particle size and surface composition are strongly affected by
    temperature, although the effect is non‐monotonic. The number density of
    redox active Mn sites is obtained from electrochemical measurements,
    and correlates well with the trends observed by XPS and LEIS. ORR
    studies of carbon‐supported LaMnO3 employing rotating
    ring‐disk electrodes show a step increase in the mean activity of
    individual surface Mn sites for particles synthesised above 700 °C. Our
    analysis emphasises the need to establish protocols for quantifying turn‐over frequency of single active sites in these complex materials to elucidate appropriate structure‐activity relationships.

    Full details in the University publications repository