Development And Photocatalytic Hydrogen Production Performance Of Novel Metal-Organic Framework Derivatives/Complexes

The global energy crisis and environmental issues were major challenges for mankind,and there was an urgent need to find clean and renewable energy to replace traditional fossil fuels.Solar energy was a ubiquitous and abundant green energy source,which was expected to alleviate the energy crisis.However,solar energy must be converted into other forms of energy and stored because it was discontinuous.Conversion to chemical energy was considered to be an ideal way.Due to its high energy density and minimal environmental pollution,the synthesis method of hydrogen attracted much attention.Photocatalytic hydrogen production from water was one of the most promising way,and it was also an effective process for converting solar energy into chemical energy.At present,a large number of researchers were looking for semiconductor materials with excellent properties for photocatalytic hydrogen production,and the factors that hindered the catalytic performance included short electron life,low sunlight utilization efficiency and so on.The current catalyst hydrogen production rate still could not meet the requirements.Metal organic frameworks（MOFs）materials had high specific surface area and adjustable pore structure,which had broad prospects in the field of photocatalysis.In this paper,novel MOF/semiconductor composites with excellent performance were synthesized.The main research contents were as follows:（1）Preparation of Zn_0.5Cd_0.5S/MIL-125-NH₂（Ti）composites and photocatalytic hydrogen production performance:In this study,a series of Zn_0.5Cd_0.5S/MIL-125-NH₂（Ti）composites with different weight ratio were prepared by simple ultrasonic method,and the photocatalytic hydrogen production were investigated under simulated visible light.When the addition amount of MIL-125-NH₂（Ti）was 40wt%,the optimum hydrogen production rate was 92.5 mmol h^-1g^-1,and the photocatalytic activity remained stable even after 16 hours.Mechanism studies shown that this excellent activity was due to proper conduction band location,enhanced visible light absorption intensity and effective electron transfer.（2）Preparation of Zn_0.5Cd_0.5S/M-TiO₂ composite material and research on photocatalytic hydrogen production performance:Sea urchin-like Zn_0.5Cd_0.5S（ZCS-2）was prepared by adding different proportions of excess sulfur source and trisodium citrate as stabilizer and structure-directing agent respectively.TiO₂（M-TiO₂）with large specific surface area was obtained by high-temperature calcination of MIL-125-NH₂（Ti）.A series of ZCS-2/M-TiO₂composites with different weight ratios were synthesized by hydrothermal method and applied to photocatalytic hydrogen production under visible light.The results shown that when the content of M-TiO₂ was 30wt%,the photocatalytic hydrogen production rate of the composite was as high as 180.4 mmol g^-1 h^-1,which was 3.5 times that of ZCS-2 and 218times that of M-TiO₂.The improvement of the photocatalytic performance of the composites were mainly due to the increase of the specific surface area,the exposure of more active sites and electrons and the improvement of the separation efficiency of electron holes.