Multifunctional carbon nanofibers coated Co-Zn alloy nanoparticles composite for efficient energy conversion and microwave absorption

Abstract

Considering the energy crisis and environment pollution, it is urgently to develop multifunctional materials to ensure the sustainable development of human society. Core-shell bimetal/carbon composites have attracted great attention in microwave absorption or electrochemical energy conversion devices, and the composite can overcome the deficient performance of pure carbon materials or pure metal materials. In this work, we proposed a simple method to prepare N-doped carbon nanofibers coated CoZn alloy nanoparticle composites (CoZn/N-CNFs) using CoZn(OH)X nanowires and melamine as precursors through pyrolysis process. The prepared CoZn/N-CNFs exhibited outstanding catalytic property for oxygen reduction reaction (ORR, half-wave potential of 0.814 V vs RHE) in alkaline solution. The CoZn/N-CNFs acted as cathode in rechargeable Zn-air batteries (ZABs) exhibited high open circuit voltage (1.33 V), large output power density (223.8 mW cm−2), and robust stability (87 h, 6 cycles), surpassing the commercial Pt/C-based ZABs. In addition, as an excellent performance electromagnetic wave absorber, CoZn/N-CNFs exhibited favorable impedance matching and electromagnetic wave absorption ability, which has the RLmin of − 33.93 dB under a thickness of 2.1 mm, and the effective bandwidth (RL<−10 dB) of 4.56 GHz with the matching thickness of 2.2 mm. This composite is expected to be a desired metal/carbon composite for ZABs and electromagnetic absorption. This work provides a simple method for the development of multifunctional materials.