Preparation Of TiO₂ Based/g-C₃N₄/RGO Composites And Its Performance Research

TiO₂ has attracted a lot of attention due to its unique physical and chemical properties.In this paper,a series of modification of TiO₂ materials is carried out by using graphene and graphite phase carbonitride/graphene,and they were used in selective organic synthesis and sodium ion batteries.In the field of selective organic synthesis,we used microwave-assisted heating to catalyze the dehydration of fructose to prepare5-hydroxymethylfurfural to test the catalytic properties of the material.In this study,the improved hummers method and high-temperature calcined urea were used to obtain graphite oxide?GO?and g-C₃N₄,respectively.Titanate nanotubes/graphene?H₂Ti₃O₇NT/RGO?composites with different graphene contents,TiO₂ nanotube/graphene?TiO₂NT/RGO?composites and TiO₂NT/g-C₃N₄/RGO with different g-C₃N₄ doping ratios were prepared by hydrothermal method using GO,P25TiO₂ and g-C₃N₄ as raw materials.The effects of microwave reaction temperature and time,graphene content,catalyst dosage and g-C₃N₄ doping amount on 5-HMF yield were investigated and their reusability was tested.The results show that H₂Ti₃O₇NT/RGO,TiO₂NT/RGO and TiO₂NT/g-C₃N₄/RGO composites can be used as catalysts for microwave-assisted conversion of carbohydrates to5-HMF.The optimal reaction conditions for the preparation of 5-HMF by the dehydration of fructose by H₂Ti₃O₇NT/RGO composites are:graphene content of 5%,reaction temperature of 150°C,reaction time of 9min,H₂Ti₃O₇NT/RGO composite material dosage of 50 mg,utilizing synergistic effect of graphene and titanate nanotube,5-hydroxymethylfurfural yield can reach 51.1%.After the catalyst was reused three times,the 5-hydroxymethylfurfural yield remains substantially unchanged indicating that the catalyst had better reusability.The optimal reaction conditions for the preparation of5-HMF by TiO₂NT/RGO composites were as follows:graphene content was 5%,reaction temperature was 160°C,reaction time was 13min,TiO₂NT/RGO composites were used in50 mg,using synergistic effect of the RGO and TiO₂NT,the yield of 5-HMF can reach61.1%.After repeated use for three times,the yield of 5-HMF does not decrease significantly showing that the catalyst has good reusability.In addition,the effects of TiO₂NT/g-C₃N₄/RGO ternary composites with different g-C₃N₄ doping amount on the preparation of 5-HMF from fructose dehydration were studied.The results showed that different g-C₃N₄ doping amount TiO₂NT/g-C₃N₄/RGO ternary nanocomposites can improve the yield of 5-HMF to a certain extent,and optimize the optimal doping amount of g-C₃N₄ to 2%.At this time,the maximum yield of 5-HMF can reach 67.2%.In the research of sodium ion battery performance,TiO₂NT,TiO₂NT/RGO,TiO₂NT/g-C₃N₄/RGO and Na₂Ti₃O₇NT,Na₂Ti₃O₇NT/RGO,Na₂Ti₃O₇NT/g-C₃N₄/RGO were used as anode materials for sodium ion batteries,and and the effects of doping RGO and g-C₃N₄/RGO on the electrochemical properties of TiO₂NT and Na₂Ti₃O₇NT were studied.Compared with TiO₂NT and Na₂Ti₃O₇NT,the sodium storage capacity of TiO₂NT/RGO,TiO₂NT/g-C₃N₄/RGO,Na₂Ti₃O₇NT/RGO and Na₂Ti₃O₇NT/g-C₃N₄/RGO electrode materials has been improved.Moreover,TiO₂NT/g-C₃N₄/RGO and Na₂Ti₃O₇NT/g-C₃N₄/RGO composite electrode materials have the best sodium storage properties.The specific performance is as follows:TiO₂NT/g-C₃N₄/RGO composite electrode material has a first discharge capacity of 772.7 mAh g^-1 at a current density of 0.1A g^-1,and the capacity remained at 138.5 mAh g^-1 after 244 cycles,even when the current density was increased to 2 A g^-1,the average discharge specific capacity of the composite electrode material was maintained at 78.6 mAh g^-1.Similarly,the first discharge capacity of Na₂Ti₃O₇NT/g-C₃N₄/RGO composite electrode material can reach 757.8 mAh g^-1 at the current density of 0.1 A g^-1 and can still be kept at 205 mAh g^-1 after 344 cycles.When the current density is increased to 2 A g^-1,the average discharge specific capacity of the composite electrode material can still be maintained at 104.7 mAh g^-1.These two materials show excellent rate performance and cyclic stability.