Block copolymer-templated nitrogen-enriched nanocarbons with morphology-dependent electrocatalytic activity for oxygen reduction

Binder-free films of nitrogen-enriched nanocarbons, prepared by the pyrolysis of polyacrylonitrile-block-poly(n-butyl acrylate) copolymer drop-casted on glassy carbon disk electrode, exhibited high electrocatalytic activity for the oxygen reduction reaction (ORR), matching that of Pt-based electrocatalyst. Dependence of the activity on pyrolysis temperature revealed that it is governed by the interplay of nitrogen content and electrical conductivity of the material. It was demonstrated that a nanocarbon formed by pyrolysis at 800 degrees C provided both large number of electrons transferred and high kinetic current density. ORR performance has been shown to critically depend on the presence of a nanoporous structure, suggesting that it facilitates high density and accessibility of catalytic sites, such as nitrogen-terminated edges of nanographitic domains.