Constructing oxygen-rich vacancies for efficient microwave absorption in Co3O4/C/N-doped carbon nanonets

With the escalating severity of electromagnetic pollution, there arises an urgent necessity to exploit microwave absorption (MA) materials. Vacancy engineering has been demonstrated to be successful approaches of developing high-performance absorbers. The Co₃O₄/C/N-doped carbon nanonets (NCNs) hierarchical composites was synthesized by utilizing 3D NCNs as the conductive matrix and flower-shaped Co-MOF derivatives as the impedance modulator in this work. The three-dimensional conductive network of NCNs facilitates the transfer and hopping of free electrons, significantly elevating the conductive loss. By modulating the pyrolysis temperature, MOF derivatives construct continuous cavity boundaries that promote multiple reflections and scattering of electromagnetic wave (EMW), while simultaneously introducing oxygen-rich vacancies to enhance polarization effects and conductivity. When the pyrolysis temperature was 350 ℃, by the successful establishment of oxygen vacancies, the NCM-350 achieved an exceptional reflection loss of −78.1 dB at 2.38 mm. This investigation introduces an approach for the adjustable MA property of absorbers, offering a viable technique to enhance dielectric loss while maintaining a balance between polarization loss and conduction loss.