Facile construction of N-doped carbon nanotubes encapsulating Co nanoparticles as a highly efficient multifunctional catalyst for electrochemical reactions

Abstract

At present, it is critical to rationally design and facilely synthesize highly cost-effective multifunctional non-noble metal electrocatalysts for sustainable energy applications. Herein, a facile solid-phase precursor pyrolysis method is used to construct N-doped carbon nanotubes encapsulating Co nanoparticles (Co@NCNTs) as a multifunctional electrocatalyst. In this method, ZIF-67 and dicyandiamide are used as the precursor and CNT growth initiator, respectively. The systematic formation process of Co@NCNTs involves a morphological evolution process from nanododecahedras, nanospheres with sparse short nanotubes to nanotubes. Owing to the synergistic effects from the inner Co nanoparticles and outer NCNTs, Co@NCNTs exhibit high multifunctional performance for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Furthermore, a primary zinc–air battery based on Co@NCNTs also shows high activity and stability. Therefore, Co@NCNTs will be a potential multifunctional catalyst for application in sustainable energy systems.