Preparation And Electrochemical Properties Of TiO₂ And Its Composite Oxides On The Surface Of Multilayer Graphene

The transitional metal oxide instead of RuO2 to prepare the super capacitor electrode materials has become a hotspot.The materials can be obtained by combining with graphene.However,it is necessary to further study how to improve the cyclic stability of the composites.In this paper,the preparation of Ti02 on the surface of graphene firstly and then the preparation of iron or cobalt metal oxide nanoparticles were carried out to improve the specific capacity and cycle performance of the electrode material.The main research contents of the paper were as follows:(1)TiO2/ML-GNS materials were prepared by hydrothermal method.The effects of reactants' amount and reaction time on the microstructure of the composites were studied and their electrochemical properties were tested.The results showed that the TiO2 particles on the surface of graphene were uniformly distributed,the particle size was less than 20nm and the crystal structure was good.Under the current density of lA/g,the specific discharge capacity was 24F/g and the specific capacity retention rate was 90%after constant current charging and discharging for 5000 times.(2)Fe2O3/TiO2/ML-GNS composites were prepared by hydrothermal method.The effect of the amount of reactants on the morphology and properties of the composites was investigated.The results showed that Fe2O3 and TiO2 nanoparticles are homogeneously complexed on the surface of grapheme and the particle size of Fe2O3 nanoparticles was 5?10nm.Under the current density of 0.5A/g,the discharge specific capacity was 152.5F/g and the specific capacity retention rate was 70.9%after cycling for 5000 times.While under the same conditions,the specific capacity of the Fe2O3/ML-GNS material without TiO2 was 134.2F/g,and the cycle retention rate was 40.5%.The Fe2O3/TiO2/GNS-CNTs materials were prepared by chemical vapor deposition(CVD)on the surface of carbon nanotubes.Under the current density of 0.5A/g,the specific discharge capacity of the composite was 164.2F/g and the specific capacity retention rate was 108.6%after cycling for 5000 times.(3)Co3O4/TiO2/ML-GNS materials were prepared by hydrothermal method.The results showed that the specific capacity of Co3O4/TiO2/ML-GNS composites was 114.5F/g at 0.5A/g,and the specific capacity retention rate was 76.2%after cycling for 3000 times.While under the same conditions,the specific capacity of the Co3O4/ML-GNS material(without TiO2)was 163.6F/g and the circulation retention rate was 39.3%.Using CVD method to prepare carbon nanotubes on the surface of the material showed that the carbon nanotube can be obtained with high aspect radio,but the electrochemical performance had not been improved.