Preparation Of TiO₂/Noble Metal Composites With High Specific Surface Area For Photocatalysis Water Splitting

Photocatalysis water splitting as one of the important ways of solar energy use,in addition to providing high energy density and non-polluting hydrogen energy,it is also expected to provide reference and help for the research of solar cells,photocatalytic CO₂ reduction,photocatalytic NH3 synthesis.Since 1972 photocatalysis water splitting was discovered by the researchers,it have been widespread concerned.However,nearly 50 years of development,the solar-hydrogen conversion efficiency of photocatalysis water splitting is still less than 10% of the minimum of industrial applications.In addition,photocatalysis water splitting is also faced with low quantum yield,low utilization of sunlight,the stability of the catalyst which needs to be improved.Therefore,the researchers have developed a new catalyst system,improve the absorption efficiency of sunlight,change the sacrificial agents,reduce the electron migration of the Schottky barrier and many other aspects of photocatalysis water splitting has been improved,and made significant effect.However,many studies have shown that the development of new catalyst system and the improvement of the performance of the original catalyst are still one of the main ways to improve the efficiency of photocatalytic conversion and reduce the cost of catalyst.Titanium dioxide（TiO₂）,as one of the earliest research and development of photocatalyst,has been widely used in environmental management,self-cleaning,water splitting,organic light synthesis,CO₂ reduction,solar cell because of its non-toxic,stable,cheap and environmentally friendly application.High specific surface area catalyst can significantly improve the active site of the catalyst,and then improve the catalytic performance of the material.However,the current synthesis of the impact of technology,high specific surface area of TiO₂ nano-materials research is still relatively few.Therefore,TiO₂ with high specific surface area was prepared by a simple synthesis technique and modified to improve the activity of photocatalysis water splitting.It is of great theoretical and practical significance to improve the hydrogen production activity of TiO₂ and to understand the performance of photocatalysis water splitting.Based on this,the photocatalytic activity of TiO₂,Ag-TiO₂ and Au-TiO₂ with high specific surface area was studied by means of water bath-light induced method.Through the characterization of the composition and morphology of the material,it is found that the pH value of the composite system can affect the specific surface area of the composite material,but also affect the shape and content of the metal nanoparticles on the TiO₂ surface.The results show that the prepared composites show excellent photocatalysis water splitting performance and are affected by the content and morphology of nobel metal nanoparticles.The main research contents include the following aspects:1.Synthesis of high specific surface area,monodisperse amorphous TiO₂ QDs and study on photocatalysis water splitting.The hydrogen production activity was tested by photocatalysis water splitting in aqueous solution.The results show that nano-TiO₂ is a good semiconductor carrier with uniform size,good dispersity,large specific surface area and active sites.The size of nanoparticles was 10.6 nm,and the photocatalytic hydrogen production rate of nano-TiO₂ was 8.2 μmol h-1 g-1.2.Study on pH control and photocatalysis water splitting of Ag Nanoparticles on TiO₂ surface.A series of Ag-TiO₂ catalysts were successfully synthesized by water bath-light induced method.It was found that the pH of the synthesis system had a significant effect on the morphology and content of Ag nanoparticles.With the increase of the pH value of the synthesis system,the Ag nanoparticles gradually changed from rod to sheet,and finally to spherel.The results of photocatalysis water splitting of Ag-TiO₂ show that the optimum hydrogenation activity of Ag-TiO₂ was 476.7μmol h-1g-1 when the pH was 2.86,the amount of AgNO3 was 1 wt%,the amount of catalyst was 0.5 g/L and the sacrificial agent was methanol.3.Study on pH control and photocatalysis water splitting of Au nanoparticles on TiO₂ surface.A series of Au-TiO₂ catalysts were prepared by water bath-light induced method.It was found that the pH of the synthesis system had a significant effect on the morphology and content of Au nanoparticles.With the increase of the pH value of the synthesis system,the Au nanoparticles changed from monodisperse sphere to spatial reticular crosslinking structures.The results of the photocatalysis water splitting of Au-TiO₂ show that the optimum hydrogenation activity of Au-TiO₂ was 1159μmol h-1g-1 when the pH was 9.00,the amount of HAuCl4 was 1 wt%,the amount of catalyst was 0.5g / L and the sacrificial agent was methanol.