Noncovalent hybrid of CoMn2O4 spinel nanocrystals and poly (diallyldimethylammonium chloride) functionalized carbon nanotubes as efficient electrocatalysts for oxygen reduction reaction Original Research Article

We have grown CoMn2O4 spinel nanocrystals on poly (diallyldimethylammonium chloride) functionalized carbon nanotubes (PDDA-CNTs) by noncovalent functionalization and solvothermal techniques. PDDA plays an important role in homogeneously increasing the surface density of available functional groups, which can provide active sites for decoration of CoMn2O4 on CNTs. In addition, PDDA preserves the intrinsic properties of CNTs, increases the active sites of catalysts, and enhances the durability of the catalysts. Here, CoMn2O4 nanocrystals were uniformly deposited on PDDA-CNTs with loading amounts from 36% to 83%. The as-prepared CoMn2O4/PDDA-CNT catalyst showed high current densities for the oxygen reduction reaction (ORR) in alkaline and neutral conditions, which outperformed the Co3O4/PDDA-CNT and Pt/C catalysts at medium overpotential, mainly through a 4e reduction pathway. The obtained CoMn2O4/PDDA-CNT hybrid exhibited excellent activity and durability when subjected to an oxygen evolution reaction. These results indicate that the CoMn2O4/PDDA-CNT hybrid represents a promising alternative to Pt for ORR electrocatalysis, and this non-precious bifunctional electrocatalyst provides a corrosion resistant and protective cathode layer to fuel cells. The excellent activity and stability of the hybrid materials demonstrate the potential of noncovalent coupling inorganic/carbon composites as novel catalytic systems for lithium–air batteries and chlor-alkali production.