Charge modulation of CNTs-based conductive network for oxygen reduction reaction and microwave absorption.

Carbon nanotube (CNTs) based composite materials are popular in various fields. However, traditional strategies for the electric conductivity modulation of CNTs is complicated and improper in large-scale applications. Herein, a novel CNTs-based hollow microsphere is prepared through facile spray drying and one-step pyrolysis. This unique interpenetration microsphere conductive network is constructed by nitrogen-doped CNTs embedded with Co nanoparticles (Co–N–C), which is compactly entangled by commercial CNTs. By the strong charge polarization and electron redistribution on the surface of Co–N–C, the monohybrids exhibit excellent bifunctional applications. The Co–N–C/CNTsHS shows excellent oxygen reduction reaction (ORR) performance including the high half-wave potential (0.87V), outstanding stability and methanol tolerance. Benefited from the improved dielectric property of Co–N–C, the Co–N–C/CNTsHS exhibits superior microwave absorption (MA) performance, with a maximum reflection loss of −60.2 dB and the bandwidth of 5.1 GHz at a thickness of only 2.5 mm. The enhanced performance can be attributed to three dimension (3D) hollow mesoporous conductive networks, which accelerate electron transfer and modulate charge distribution of Co–N–C. This work puts forward a new idea of charge modulation of CNTs and lays a foundation for the preparation of excellent bifunctional materials. A new strategy of conductive modulation of CNTs is developed to construct porous hollow composite microsphere, which is composed of Co–N–C and commercial CNTs. The composite exhibits excellent bifunctional performance of ORR and MA. This work may lay the foundation electrical conductivity of CNTs and open the door for the preparation of outstanding bifunctional materials. [Display omitted] [ABSTRACT FROM AUTHOR]