Membrane-Solvothermal Synthesis of Cobalt Ferrite/Reduced Graphene Oxide Nanocomposites and Their Photocatalytic and Electromagnetic Wave Absorption Properties

Cobalt ferrite (CoFe2O4) nanorods have been synthesized by a membrane-solvothermal method and a series of CoFe2O4/rGO nanocomposites with different reduced graphene oxide (rGO) weight ratios of 5%, 10%, 15%, 20%, 25% and 30% have been synthesized via ultrasonic treatment, named as CoFe2O4/rGO-1, CoFe2O4/rGO-2, CoFe2O4/rGO-3, CoFe2O4/rGO-4, CoFe2O4/rGO-5 and CoFe2O4/rGO-6, respectively. The photocatalytic activity was studied by photodegradation of malachite green (MG), and the wave absorbing performance was studied by network vector analyzer. CoFe2O4 had the function of magnetic separation, which had largely reduced the separation difficulty of photocatalyst and dye wastewater. Among all the graphene-based composites, CoFe2O4/rGO-5 has the most excellent photocatalytic performance which could eliminate about 93.48% of MG in 90 min. Even after five cycles, the photocatalytic degradation rate of MG was still above 88%, suggesting that CoFe2O4/rGO-5 is a promising photocatalyst for recyclable utilization. The wave absorption test results showed that the electromagnetic wave reflection loss of CoFe2O4/rGO nanocomposites was lower than that of pure CoFe2O4, which showed that the addition of graphene could effectively enhance the absorbing properties of materials. When the thickness of the absorbing layer was 2.5 mm, the reflection loss of the CoFe2O4/rGO-4 nanocomposite reached the maximum value of 17 GHz at -11.1 dB and the bandwidth of less than -10 dB was 2.3 GHz.