A new isolation protocol was recently reported for highly purified metallic Fullertubes D5h -C90 , D3d -C96 , and D5d -C100, which exhibit unique electronic features. Here, we report the oxygen reduction electrocatalytic behavior of C60 , C70 (spheroidal fullerenes), and C90 , C96 , and C100 (tubular fullerenes) using a combination of experimental and theoretical approaches. C96 (a metal-free catalyst) displayed remarkable oxygen reduction reaction (ORR) activity, with an onset potential of 0.85 V and a halfway potential of 0.75 V, which are close to the state-of-the-art Pt/C benchmark catalyst values. We achieved an excellent power density of 0.75 W cm-2 using C96 as a modified cathode in a proton-exchange membrane fuel cell, comparable to other recently reported efficient metal-free catalysts. Combined band structure (experimentally calculated) and free-energy (DFT) investigations show that both favorable energy-level alignment active catalytic sites on the carbon cage are responsible for the superior activity of C96 .
Keywords: Band Alignment; C96; Electrocatalysis; Fullerenes; Molecular Catalysis; Oxygen Reduction Reaction.
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