Jagged carbon nanotubes from polyaniline: Strain-driven high-performance for Zn-air battery

Abstract

Metal-free carbons with editable morphologies, heteroatom ensembles and abundant defects have been considered as a kind of promising candidate alternative to platinum group metal (PGM)-based catalysts for oxygen reduction reaction (ORR). Herein, we fabricated well-defined jagged carbon nanotubes (JCNTs) derived from polyaniline with inherent twisted molecular chains, through controllable ZnCl2-assisted carbonization and NH3-activation. The obtained JCNTs feature a large structural strain caused by abundant at-edge zigzag or armchair sites composed of carbon and nitrogen atoms in the JCNTs. There exists a strain-dependent ORR activity exceeding state-of-the-art Pt/C in alkaline medium, with the half-wave potential reaching 0.88 V (vs RHE). Zn-air battery equipped with the catalyst as cathode exhibits a power density of up to 142 mW cm−2 and long-term charge–discharge cycle stability. The moderate compressive strain can efficiently activate the metal-free carbon and lower the reaction energy barrier, facilitating ORR kinetics. It may shed light on developing strained nanocarbons with high-performance as next-generation catalysts for batteries and fuel cells.