Efficient and methanol resistant noble metal free electrocatalyst for tetraelectronic oxygen reduction reaction

Abstract

Efficient dispersion of M-N-C molecular macrocycles on carbon nanomaterials support is an attractive strategy to develop a highly efficient and noble metal-free Oxygen Reduction Reaction (ORR) electrocatalyst for fuel cell devices. Herein, Cobalt Phthalocyanine (CoPc)/reduced graphene oxide (rGO) nanocomposite has been synthesized through non-covalent functionalization of CoPc and GO followed by electrochemical reduction of the resulting hybrid. A comprehensive structural, topographic and morphologic study on the nanocomposite confirmed the GO and CoPc assembly based on π-π interaction and electrochemical reduction leads to enhanced dispersion of CoPc aggregates by breaking its microparticles into nanoclusters. A chemical mapping of the catalysts surface by Confocal Raman Imaging further proved that CoPc and GO phase is homogeneously distributed and impregnated into each other as a result of the electrochemical reduction. The ORR activity of the CoPc/rGO was evaluated through voltammetry and amperometry techniques, which revealed a synergic ORR catalysis at the composite surface highlighted by larger current densities, 300 mV positive shift of the onset potential, and negligible generation of H2O2 as compared to CoPc and GO. In addition, the composite material revealed better stability and resistance to methanol poisoning than a commercial Pt/C catalyst, and such features make it ideal for application in methanol fuel cells.