Study On Photocatalytic Properties Of Carbon Dots And Titanium Dioxide Systems

As an ideal environmentally-friendly energy,hydrogen has emerged as a promising alternative to traditional carbon-based fossil fuels and can alleviate the energy and environment crisis.Specially,hydrogen evolution by solar-driven photocatalysis is one of the most desirable routes to low-cost hydrogen energy.The establishment of photocatalysts with visible-light absorption,high catalytic efficiency and stability is among the research center for photocatalytic hydrogen evolution.Carbon dots（CDs）,due to their tunable optical properties,excellent electron-transfer abilities and earth abundant nature have found application in this field.In this issue,Carbon dots are obtained through hydrothermal,electrochemical and ultrasonic treatment.By comparison of photocatalytic NO oxidation performance of CDs/P25 TiO₂ composites,the approach to Carbon dots have been optimized as the hydrothermal process.Subsequently,the photocatalytic hydrogen evolution based on hydrothermal CDs and TiO₂ have been studied.The results show that the photocatalytic activity of {001}TiO₂ is enhanced by CDs while that of P25 TiO₂,anatase,{101}TiO₂ and {100}TiO₂ are inhibited.Therefore,the photocatalytic hydrogen evolution over CDs-doped {001}TiO₂ is systematically investigated.It is shown that the highest photocatalytic efficiency is achieved when {001}TiO₂ is loaded with 0.5 wt%CDs because of the sufficient separation of photo-induced charge carriers.And such a system exhibits a good photostability.Doping is an effective method to further promote the catalytic properties of CDs,hence N、S and B atoms are introduced into CDs to adjust the optical characters of CDs.With suitable synthetic avenue,the as-prepared doping CDs are confirmed to facilitate the visible-driven photocatalytic hydrogen evolution performance of TiO₂.In conclusion,this project is focused on the fabrication and modification of CDs as well as the photocatalytic hydrogen evolution of CD/TiO₂ heterostructures,which is beneficial for the construction of highly efficient CD-based photocatalysts.