Structure Engineering And Photocatalytic Application Of TiO₂-based Nanocrystals

Recently,energy shortage and environmental contamination are the current two of nost common challenges globally,which are mainly attributed to the rapid industrial clopment and population growth.Photocatalysts can convert the abundant and easily lable natural solar energy to chemical energy,for clean energy production and ronmental remediation.Therefore,the development of highly efficient and ainable photocatalysts becomes an imperative task.The thesis is focused on the engineering and photo structural catalytic application of?-based nanocrystals,and its main contents and innovations include three parts.ovel hierarchical TiO2 nanocrystals are synthesized via a hot-injection method,and formation mechanism is specifically studied.The corresponding photocatalytic brmance is optimized by the structural engineering of TiO2 nanocrystals.F-is the key to the formation of hierarchical structural and the structure engineering.Firstly,F-induces the oriented attachment progress as a capping agent,leading to the formation of hierarchical structure.Secondly,the doping of the F element causes the appearance of oxygen vacancy and Ti3+,thus affecting the electronic structure of TiO2 nanocrystals.The photocatalytic performances of the TiO2 nanocrystals could be optimized by regulating morphological factors such as specific surface area and electronic structures such as band gap and defects concentration,through systematic manipulation of reaction parameters,including the amount of titanium precursors and NaF,the reaction temperature and reaction time.The hydrogen evolution performance of TiO2 bouquets is the best,with the rate of 2033.6 ?mol g-1·h-1.iO2 nanocrystals with distinct morphologies are synthesized through the seed-iated method,under the inducing of halogen(F or Cl),and the structure and ocatalytic performance of TiO2 nanocrystals are optimized.Unique core-antenna and cubic TiO2 nanocrystals are prepared with F-as inducing agent and dopant.The specific study of the corresponding formation mechanism demonstrates that the dosage of F affects the shape and electronic structure of TiO2 nanocrystals.With the balance of band gap,specific surface area and electronic structure,TiO2 nanocrystals with core-antenna structure have an excellent photocatalytic performance.(?)The seed-mediated method is extended to the Cl case where Cl-is acted as a capping agent and dopants.The photocatalytic degradation and hydrogen evolution performance of TiO2 nanocrystals synthesized via the seed-mediated method are excellent.3.TiO2-Ag@Cu2O nanocomposites are designed and fabricated for the improvement of photocatalytic performance,and the hydrogen evolution performance is further optimized by regulation of morphology.(?)TiO2-Ag@Cu2O nanocomposites are designed,fabricated and specifically characterized.The broader absorption range,lower recombination rate of the photo-generated carriers can be attributed to the improved hydrogen evolution rate of TiO2-Ag@Cu2O,which is as high as 125 times that of pure TiO2 with quasi-spherical shape.(?)The photocatalytic performance of TiO2-Ag@Cu2O is optimized by the regulation of shape.The hydrogen evolution rate of rod-like TiO2 rod-Ag@Cu2O is the high up to 1861.3 ?mol g-1·h-1,like 10 times that of TiO2-Ag@Cu2O based on quasi-spherical TiO2 nanocrystals.