Noble Metal-Free Oxygen Reduction Reaction Catalysts Derived from Prussian Blue Nanocrystals Dispersed in Polyaniline.

A highly efficient noble-metal-free catalyst for the oxygen reduction reaction (ORR) is derived from a composite of polyaniline (PANI) and Prussian blue analogue (PBA, Co3[Fe(CN)6]2) by pyrolysis. The composite consists of 2-5 nm PBA nanocrystals homogeneously dispersed in PANI. During the pyrolysis, the PBA nanocrystals serve as both the template for the pore formation and the precursor for the ORR active sites, which results in a nanoporous structure strongly coupled with the ORR active sites. The catalyst exhibits superior ORR performance in both alkaline and acidic electrolyte, comparable to that of the commercial Pt/C with 20 wt % Pt loading.