Manganese oxide nano flakes onto simultaneously activated defective CNTs for the creation of CNTs-graphene supported oxygen reduction composite catalysts applied in air fuel cell

TL;DR

This study develops manganese oxide nano flakes on defective CNTs to create efficient oxygen reduction catalysts, enhancing air fuel cell performance with a novel synthesis method that improves power output.

Contribution

It introduces a new synthesis approach for CNT-supported manganese oxide catalysts with defect engineering, leading to improved ORR activity and fuel cell efficiency.

Findings

CMnCs outperform raw CNTs and market catalysts in ORR activity.

Fuel cells with CMnCs achieve ~15% higher power output at 100 mA/cm².

Manganese oxide flakes are homogeneously grown on CNT surfaces, enhancing reactivity.

Abstract

Rational combination holds the key for non-precious metal oxides and economic carbon materials to the creation of high performance air electrode materials. Carbon nanotubes (CNTs)-supported manganese oxides composite catalysts (CMnCs) were obtained by reacting commercial CNTs with MnO$_4^-$ in diluted H$_2$SO$_4$ with cancelling conventional hydrothermal processing or adding surfantant templates. CMnCs were then assembled into commercial air cathodes equipped in metal air fuel cells. CNTs demonstrated structurally much defective. Outer CNT walls were cracked into graphene nano pieces yet remaining partially attached to inner carbon tubes during synthesis. This exposure of graphene planes exhibited additional oxygen reduction reactivity. Manganese oxide flakes identified as {\gamma}-MnOOH were homogeneously grown on surfaces of CNTs at nano sizes. Its deposition density was closely related to the additive amount of KMnO$_4$ with regard to CNTs. The ORR activities of sole CMnCs exceeded both raw CNTs and competent market catalysts under identical conditions, and with current production technics the CMnCs-ingrediented air fuel cells were capable of outputting ~15% more power at 100 mA/cm$^2$.