Functionalized cobalt porphyrin immobilized multiwalled carbon nanotubes are synthesized and characterized. These new materials efficiently electrocatalyze oxygen reduction and they have potential to replace conventional Pt–C catalyst in fuel cells.

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In the search for alternative sources to replace fossil fuels, carbon nitride materials can be used in a variety of ways. In the present work, porosity is introduced to the carbon nitride material using mesoporous silica material, MCM-41, as a hard template, and a mesoporous carbon nitride (MCN) material is synthesized. Further, the MCN is modified by immobilizing metal phthalocyanine (MPc, where M = Mn, Fe, Co, Ni, Cu, and Zn). The resulting MPc-incorporated MCN materials (MPc@MCN) were tested for the electrocatalytic oxygen reduction reaction (ORR) in acidic and basic media. Detailed studies reveal that the FePc@MCN and CoPc@MCN materials exhibit higher ORR activity than the other composites in 0.1 M KOH. FePc@MCN follows a direct four-electron oxygen reduction mechanism and shows ORR onset potential (vs RHE) at 0.93 V (in 0.1 M KOH), which is very close to the onset potential exhibited by the state-of-the-art material, Pt-C (1.0 V), and higher than several similar composites of MPc with carbon supports tested in similar environments. Besides, due to the inherent property of coordination through nitrogen present on the MCN, FePc@MCN shows excellent stability even after 3000 cyclic voltammetry (CV) cycles. FePc@MCN was found to have a better methanol tolerance in comparison to Pt-C in basic medium. CoPc@MCN shows a highly selective two-electron reduction reaction in both acidic and basic media at lower overpotential than many of the reported catalysts for the two-electron oxygen reduction. Therefore, these materials (FePc@MCN and CoPc@MCN) can be used as suitable alternatives to replace Pt and other expensive materials in ORR and related applications.