Preparation Of TiO₂ Photocatalyst With Metal-graphene Synergistic Modification And Study On The Interpretation Of Hydrogen With Ammonia Borane Water By Visible Photocatalysis

Because of its advantages of high calorific value and no pollution,hydrogen energy has become a great potential new energy.In the large-scale utilization of hydrogen energy,the storage of hydrogen energy is the key.Among many hydrogen storage materials,Ammonia borane（NH₃BH₃,AB）has become the most potential hydrogen storage material by virtue of its high hydrogen storage capacity（19.6 wt%）,excellent stability and low cost.In the hydrogen release method of ammonia borane,photocatalysis has been widely concerned.By modifying the photocatalyst to improve the photocatalytic performance,ammonia borane can realize stable hydrogen release under visible light.At room temperature,1 mole of NH₃BH₃ can hydrolyze to release 3moles of hydrogen.In this paper,TiO₂ based photocatalyst was prepared by solvothermal method,and by means of XRD,SEM,UV-vis DRS,FT-IR and Raman to characterize its structure and properties,then studied photocatalysis of ammonia borane hydrolysis to interpret hydrogen.Using solvothermal method to prepare the same doping concentration of Fe³⁺,Co²⁺,Ni²⁺and Cu²⁺doped TiO₂ photocatalysis materials,through the material characterization and the study of photocatalysis of ammonia borane hydrolysis,it found that Fe³⁺modified TiO₂ has the highest visible photocatalytic efficiency.On this basis,the amount of Fe³⁺doping affects the photocatalytic activity of TiO₂ has been studied,and found that 2%of Fe³⁺doped TiO₂ photocatalyst is the best by the ammonia borane photocatalytic effect,The hydrogen release rate of material was628.76μmol·min^-1·g_ca^-1 _t.Then three repetitive experiments were carried out on the sample,the photocatalytic performance of the sample was not significantly reduced.Because of excellent physicochemical properties of graphene,TiO₂ photocatalysis materials with different amount of graphene modification were prepared by solvothermal method.Through the material characterization and the study of photocatalysis of ammonia borane hydrolysis,it found that 1%of graphene modified TiO₂ photocatalyst is the best by the ammonia borane photocatalytic effect.On this basis,considering the influence of the solvothermal reaction time on the properties of the material,the solvothermal reaction time of the material continues to be changed.When the solvothermal reaction time is 12 h,the visible light catalytic properties of the material is the best,the hydrogen release rate of material was 1088.93μmol·min^-1·g_ca^-1 _t.Then three repetitive experiments were carried out on the sample,the photocatalytic performance of the sample was not significantly reduced.Because the addition of metal ions and graphene may have a synergistic effect on the modification of TiO₂,TiO₂ photocatalysis materials with different amounts of Fe³⁺and graphene adjunction were prepared by solvothermal method.Through the material characterization and the study of photocatalysis of ammonia borane hydrolysis,it found that the addition of both does indeed further improve the photocatalytic activity of TiO₂,and when the Fe³⁺doping amount was 2%and graphene addition amount was1%,the visible light catalytic efficiency of the composite is the highest,the hydrogen release rate of material was 1235.32μmol·min^-1·g_ca^-1 _t.Then three repetitive experiments were carried out on the sample,the photocatalytic performance of the sample was not significantly reduced.After that,the sample was used as the raw material to explore the environmental factors of ammonia borane photocatalysis.It found that the size of the optical output power and hydrogen release rate of ammonia borane photocatalysis hydrolysis were positively correlated,the addition amount of photocatalyst and concentration of ammonia borane aqueous solution both exist optimal values.Within the scope of this experiment,the optimal addition amount of photocatalyst was 0.4 g,the optimal concentration of ammonia borane aqueous solution was 1.296 mol/L,hydrogen releasing rate of reaction system could be 181.32μmol·min^-1,hydrogen releasing rate of the material in this reaction system could be 453.3μmol·min^-1·g_ca^-1 _t.Based on the above characterization and analysis of experimental results,the possible reaction process of TiO₂ photocatalytic material for hydrogen release of ammonia borane photocatalysis was obtained.