Simultaneous Phase- and Size-Controlled Synthesis of TiO_2 Nanorods via Non-Hydrolytic Sol-Gel Reaction of Syringe Pump Delivered Precursors

摘要

The simultaneous phase- and size-controlled synthesis of TiO_2 nanorods was achieved via the non-hydrolytic sol-gel reaction of continuously delivered two titanium precursors using two separate syringe pumps.As the injection rate was decreased,the length of the TiO_2 nanorods was increased and their crystalline phase was simultaneously transformed from anatase to rutile.When the reaction was performed by injecting titanium precursors contained in two separate syringes into a hot oleylamine surfactant solution with an injection rate of 30 mL/h,anatase TiO_2 nanorods with dimensions of 6 nm (thickness) x 50 nm (length) were produced.When the injection rate was decreased to 2.5 mL/h,star-shaped rutile TiO_2 nanorods with dimensions of 25 nm x 200 nm and a small fraction of rod-shaped anatase TiO_2 nanorods with dimensions of 9 nm x 100 nm were synthesized.Pure star-shaped rutile TiO_2 nanorods with dimensions of 25 nm x 450 nm were synthesized when the injection rate was further decreased to 1.25 mL/h.The simultaneous phase transformation and length elongation of the TiO_2 nanorods were achieved.Under optimized reaction conditions,as much as 3.5 g of TiO_2 nanorods were produced.The TiO_2 nanorods were used to produce dye-sensitized solar cells,and the photoconversion efficiency of the mixture composed of star-shaped rutile TiO_2 nanorods and a small fraction of anatase nanorods were comparable to that of Degussa P-25.