Highly active non-precious metal catalyst based on poly(vinylpyrrolidone)- wrapped carbon nanotubes complexed with iron-cobalt metal ions for oxygen reduction reaction

Multi-walled carbon nanotubes (MWCNTs) are functionalized with 2-pyrridone functional groups by wrapping poly(vinylpyrrolidone) polymers around it under high-powered sonication. The presence of 2-pyrridone functional groups facilitates the complexation of metal ions (Fe ³⁺, Co ²⁺). The best oxygen reduction catalyst, MWCNT-FeCo, is synthesized by annealing poly(vinylpyrrolidone)/MWCNTs/Fe-Co complex in ammonia at 900 °C and exhibits nearly four-electron oxygen pathway (n ∼3.8). X-ray diffraction pattern shows that low loading of metallic Fe nanoparticles (0.79 wt.%) and bimetallic FeCo nanoparticles (0.34 wt.%) is formed on the MWCNT-FeCo catalysts. X-ray photoelectron spectroscopy reveals that ∼1 at.% of nitrogen has been doped into MWCNT-FeCo catalysts.