Facile Synthesis Of Amorphous TiO₂ Nanorods Decorated RGO Hybrid Composites With Wide Band Microwave Absorption

With the rapid development of 5G technology,the integration of electronic communication equipment and the upgrading of military stealth technology,traditional microwave absorption materials such as ferrites,magnetic metal particles can no longer meet the current needs due to their high density and poor stability.The development of lightweight high-performance microwave absorption materials has become a key research direction in the field of functional materials.Titanium dioxide（TiO₂）has shown great potential for microwave absorption owing to its low density,high stability and non-toxic characteristics.However,the following key problems limits its further application to microwave absorption:1)poor impedance matching properties resulting from low complex permittivity;2)weak polarization capability leading to poor dielectric loss.In this thesis,the polarization loss is enhanced by designing amorphous TiO₂ structures which contains more disorders and defect sites.Then the amorphous TiO₂structures are further compounded with reduced graphene oxide（rGO）,which has excellent electron transport capacity.On the one hand,the polarization capacity of the composites is further enhanced by the large specific surface area and abundant surface functional groups of rGO.On the other hand,the impedance matching property is improved by the high complex permittivity of rGO.The main contents are as follows:The amorphous TiO₂ nanorods are homogeneously compounded on the rGO lamellae by a one-step solvothermal method to form a two-dimensional/one-dimensional composite structure,which not only prevents the stacking of rGO lamellae but also enhances interfacial polarization to dissipate microwave efficiently.The density of TiO₂ nanorods can be well controlled by adjusting the addition amount of tetrabutyl titanate（TBT）.Then the electromagnetic parameters and wave absorption properties of the composite with different amorphous TiO₂ density are systematically studied.The minimum reflection loss of the composite reaches-42.8 d B and the widest efficient absorption bandwidth is up to 6.2 GHz,which achieves the absorption in full Ku band.In addition,after the conversion from amorphous TiO₂ to crystalline TiO₂ through annealing treatment,this thesis also investigates the degradation of the microwave absorption resulting from the decrease of the polarization loss.Finally,the internal mechanisms of the microwave absorption are analyzed in combination with the impedance matching and dielectric loss.In conclusion,the amorphous TiO₂/rGO composites prepared by the facile synthesis process have achieved the synergistic effect between impedance matching,quarter-wavelength matching and dielectric loss,exhibiting excellent microwave absorption performance.This thesis not only brings new solutions for designing high efficient microwave absorbers,but also provide a facile method to reduce the preparation cost and difficulty,and has good prospects for industrial application.