The applications of cobalt ferrite and nickel ferrite composite materials on electromagnetic (EM) wave absorption are the research hotspot currently. However, the systematical comparison study between these two ferrites composites have rarely been carried out. Thus, the EM wave absorption performance of interconnected carbon@Ni x Co 1-x Fe 2 O 4 composites with core–shell structures were investigated comprehensively in this work. A series of magnetic nanospheres including NiFe 2 O 4 , cobalt-doped nickel ferrite, nickel–cobalt ferrite, nickel-doped cobalt ferrite and CoFe 2 O 4 were synthesized firstly, and then uniformly encapsulation by carbon rendered the corresponding C@Ni x Co 1-x Fe 2 O 4 composites nanospheres. Synthesis reactions involved for C@Ni x Co 1-x Fe 2 O 4 formation were investigated in detail, and afterwards their magnetic behavior, EM wave absorption performance and absorbing mechanism were thoroughly explored and analyzed. Results show that when nickel is dominant element and cobalt is doping element (Ni 0.75 Co 0.25 Fe 2 O 4 ), the composite nanosphere exhibits optimum EM wave absorption performance. When the sample thickness is just 1.9 mm, its RL min value can reach −51 dB, and the corresponding EAB width is 3.3 GHz. The synthesized C@Ni 0.75 Co 0.25 Fe 2 O 4 can be qualified as an efficient and thin electromagnetic wave absorber, which is mainly attributed to its special structure, fair electromagnetic matching and impedance matching.
Van Ngo Hoanh,Nguyen Hung Tran,Le Hieu Trung,Le Thanh Huu,Vu Thien Tri,Pham Kien Trung,Phung Thinh Xuan
A study area in supercapacitor research is the design and manufacturing of composite electrode materials that combine the advantages of various materials. The rGO/CoFe 2 O 4 composite material is produced by growing cobalt ferrite particles on the surface of rGO using a simple and highly efficient thermal reduction technique. The results show that the electrochemical properties of rGO are significantly improved by the incorporation of cobalt ferrite. rGO sheets are used as supporting frameworks for the CoFe 2 O 4 nanoparticles, while the CoFe 2 O 4 particles provide more active sites for redox reactions. The prepared rGO/CoFe 2 O 4 show excellent electrochemical properties, with a high specific capacitance of 283 F/g at a current density of 0.1 A/g and a specific capacitance retention of 90.5% after 1000 cycles. The attractive performances exhibited by rGO/CoFe 2 O 4 composites make them potential electrode materials for supercapacitors in future.
危险品化学品经营许可证（带存储）