In-situ construction of 1D/2D CoNiO₂/RGO heterojunctions for enhanced microwave absorption

The urgent need for efficient electromagnetic (EM) wave absorbing materials is driven by the increasingly severe issue of EM radiation. Heterostructures assembled from nanoscale building blocks, not only inherit the advantages from the single component but also create novel properties. Herein, the CoNiO₂ nanowires were grown in situ and tightly anchored onto reduced graphene oxide (RGO) nanosheets via a hydrothermal process followed by annealing treatment. The aggregation and restacking of RGO nanosheets is inhibited by the CoNiO₂ nanowires. The construction of 1D/2D heterojunction not only effectively reduces the conductivity of RGO, thereby improving the impedance matching of CoNiO₂/RGO composites, but also brings about strong interface polarization that governs high-frequency polarization loss. Furthermore, the microwave absorption performance of the CoNiO₂/RGO composites could be finely tuned by varying the precursor content. Benefiting from the multiple advantages of the 1D/2D heterojunction, the optimized CoNiO₂/RGO composite at a low filler loading of 20 wt% achieves a minimum reflection loss value of −53.75 dB and an effective absorption bandwidth of 4.70 GHz. Furthermore, the actual effectiveness of the composite is verified through radar cross-section simulation. This work opens a new avenue to enhance EM wave absorption performance of 2D graphene-based heterojunctions.