Study On The Synthesis And Photocatalytic Properties Of Novel TiO₂ Nanosheets Composite Photocatalytic Materials

The over-exploitation of traditional energy sources leads to energy shortage,which also aggravates the environmental problems.In response,scientists have turned to hydrogen.Photocatalytic decomposition of water is a promising technology to produce clean,environmentally friendly and low-cost hydrogen energy from solar energy.As the most representative photocatalytic material,Ti O₂once became the focus of research due to its excellent performance such as low cost and stable property.However,Ti O₂also has many development limitations,such as wide band gap,rapid carrier recombination and ultraviolet excitation,which limit the application of Ti O₂.On the basis of investigation of domestic and foreign literatures,this paper conducts research on Ti O₂nanometer sheets and modifies them by different methods to improve their photocatalytic performance.（1）The preparation of Ni Mo S/Ti O₂composite photocatalytic materials was realized by hydrothermal method.A series of test methods,such as XRD,TEM and XPS,were used to characterize the microstructure of Ti O₂/Ni Mo S composite materials.DRS,PL,SPV and other technologies were used to explore the photogenerated charge migration and separation behavior.The results of photodissociation of aquatic hydrogen performance showed that the hydrogen production performance of Ni Mo S/Ti O₂composite photocatalytic system was significantly improved compared with that of pure Ti O₂,and Ni Mo S load reached the highest at 3%.The hydrogen production rate of the composite photocatalytic material is about 1607.06μmol·g^-1·h^-1,187 times that of pure Ti O₂.Finally,a suitable mechanism was proposed to explain the enhancement of photocatalytic activity.（2）Firstly,Co₃O₄was loaded onto Ti O₂by hydrothermal method,and then,in order to find the optimal performance ratio（1.5%）,photocatalytic hydrogen production experiments were conducted on samples with different load capacities.On this basis,Pt nanoparticles were deposited on 1.5%Co₃O₄/Ti O₂composite photocatalyst by photoreduction method to synthesize Ti O₂/Co₃O₄/Pt dual catalyst.When the feed ratio of Pt was 1.5%,the maximum value of hydrogen production was 20.48mmol·g^-1·h^-1,which was 1.6 times higher than that of Pt/Ti O₂sample.Compared with Co₃O₄/Ti O₂composite photocatalytic materials,the increase was about 13 times,and compared with pure Ti O₂,the increase was 358 times.The results of hydrogen production performance of composite photocatalytic materials showed that Co₃O₄and Pt formed a good contact interface with Ti O₂,which was conducive to further directional separation of electron hole pairs.（3）Ni WO₄was supported on the surface of Ti O₂by ion stirring method,and Pd was compounded by chemical reduction.After Ni WO₄was added,the two formed z-shaped heterojunction,which strengthened the separation of carriers.Pd nanoparticles themselves have the function of receiving electrons,which acts as an electron channel,hinders the high-speed recombination of electron hole pairs,and improves the photocatalytic activity.The results show that the new material Ni WO₄has excellent performance and is worthy of more research and application.