Preparation And Photocatalytic Performance Study Of Non-Metallic Doped TiO₂ Composite

Titanium dioxide has been widely studied by scholars because of its non-toxicity,low preparation cost,and its great potential for environmental and energy applications.However,TiO₂is not an excellent Photocatalyst.On the one hand,TiO₂has a wide bandgap energy gap（3.0e V for rutile and 3.2e V for anatase）,which can only account for less than 5%of ultraviolet light in sunlight.therefore,it can not make full use of solar energy;on the other hand,Photogenerated electrons and Photogenerated holes generated by TiO₂after being excited by light are easily recombined,thereby reducing quantum efficiency.Non-metallic doping has been reported to have a good effect to expand the spectral response of titanium dioxide.Therefore,in this thesis,the sulfur source,nitrogen source and nitrogen sulfur source are used to dope the titanium dioxide.It is expected that they have excellent visible light catalytic properties,which provides a reference for the design and development of non-metal doped Photocatalysts.Titanium tetrafluoride and titanium sulfate were the mixed titanium sources,and sodium dithionite was used as the doping sulfur source.The black sulfur-doped titanium dioxide was synthesized by one-step solvothermal method using anhydrous ethanol as solvent.XPS,EDS and FT-IR characterization confirmed that the sulfur element was successfully doped into titanium dioxide.The visible light catalytic performance of sulfur-doped titanium dioxide was evaluated by degrading Rhodamine B solution.It was found that the visible light catalytic activity of sulfur-doped titanium dioxide was significantly improved compared with P25.The Photocatalyst which obtained by using 5 mmol sodium dithionite has the highest visible light catalytic activity,which shows a 18.5 fold Photocatalytic activity improvement of P25.The Rh B Photodegradation efficiency changed relatively little after 5 cycles of experiment under identical condition,indicating that the Photocatalyst has superior Photocatalytic stability.Solvothermal reaction temperature、reactant、calcination temperature and other factors that may affecting the Photocatalyic performance have been systematically discussed individually.It was found that the sulfur-doped titanium dioxide synthesized by reacting at 180°C,mixed titanium source and no calcined process,has the best visible light catalytic performance.Finally,the main active species produced by sulfur-doped titanium dioxide under visible light were investigated by active species capture experiments.Titanium tetrafluoride and titanium sulp Hate were used as mixed titanium source,thiourea dioxide was used as a nitrogen-sulfur co-doped source,and anhydrous ethanol was used as solvent to synthesize black nitrogen-sulfur co-doped titanium dioxide by one-step solvothermal method.XPS and FTIR characterization confirmed that the nitrogen and sulfur elements were successfully doped into titanium dioxide.The visible light catalytic performance of nitrogen-sulfur co-doped titanium dioxide was evaluated by degrading rhodamine B solution.It was found that the visible light catalytic activity of nitrogen-sulfur co-doped titanium dioxide was prominently better than P25.The Photocatalysts obtained using 12 mmol of thiourea dioxide has the highest visible light catalytic activity,much higher than P25,it can completely degrade the rhodamine B solution within 90 minutes.The Rh B Photodegradation efficiency changed relatively little after 5 cycles of experiment under identical condition,indicating that the Photocatalyst has superior Photocatalytic stability.Finally,the active species produced by nitrogen-sulfur co-doped titanium dioxide under visible light were discussed by active species capture experiments.Titanium tetrafluoride and titanium tetrachloride were the mixed titanium sources,urea was used as the nitrogen source,and anhydrous ethanol was used as the solvent to synthesize N-doped titanium dioxide by one-step solvothermal method.XPS characterization confirmed the successful doping of nitrogen into titanium dioxide.By adjusting the ratio of different nitrogen sources,we found that the incorporation of nitrogen source reduced the visible light catalytic performance of the catalyst,while TN-0 showed higher catalytic performance and it can completely degraded the rhodamine B solution within 60 minutes.We used TN-0 Photocatalyst to degrade phenol in visible light,and found that phenol was degraded into hydroquinone and p-benzoquinone.In combination with the reference,we calculated the concentration of hydroquinone,which provided an another green organic conversion method.