Fabrication of yolk-shell NiCo alloy@C composites derived from trimetallic metal-organic frameworks as light-weight and high-performance electromagnetic wave absorbers

Developing the high-performance electromagnetic wave (EMW) absorbers with the characteristics of thin thickness, broad bandwidth and strong absorption against the increasingly serious electromagnetic pollution was still a great challenge. In this work, NiCo alloy@C (NCC) composites were fabricated through high-temperature pyrolysis of trimetallic NiCoZn metal-organic framework. Results showed that the NCC composites displayed a unique yolk-shell structure, and the carbonization temperature had a great influence on the crystal structure, graphitization degree and micromorphology. Moreover, the electromagnetic parameters and absorption capacity could be regulated by adjusting the carbonization temperature and filler contents. Significantly, the obtained NCC composite presented the integrated optimal absorption capacity, including the minimum reflection loss of -61.9 dB under an ultrathin thickness of 1.5 mm and a wide absorption bandwidth of 6.0 GHz at 1.7 mm. Additionally, the underlying absorption mechanisms were revealed. Our results could offer a new approach to fabricate light-weight and high-efficiency EMW absorbers.

Automated summary

NiCo alloy@C (NCC) composites with a unique yolk-shell structure were fabricated through high-temperature pyrolysis, showing the potential to regulate electromagnetic parameters and absorption capacity by adjusting the carbonization temperature and filler contents. The achieved NCC composite demonstrated the integrated optimal absorption capacity with minimum reflection loss under an ultrathin thickness and wide absorption bandwidth, with underlying absorption mechanisms revealed.