Study On TiO₂-Based Composite Nanomaterials:Preparation And Their Photocatalytic Performance

In the face of the increasingly serious energy shortage and environmental pollution,It has become a hot research topic to look for a photocatalyst that can effectively use solar energy to degrade organic pollutants.In numerous photocatalysts,TiO₂ photocatalyst shows high catalytic activity,and its physical and chemical properties are stable,non-toxic side effects,low cost.However,the conventional TiO₂ can only absorb ultraviolet light as its wide forbidden band?3.2 eV?.Therefore,the modification research of TiO₂ ususlly focus on broadening its light response range and improve the absorption of visible light to make full use of sunlight.Based on these,composite nanostructures with p-n junction were prepared by complexing excess metal oxides with TiO₂.And the photocatalytic activity of as-prepared photocatalysts are researched by the degradation of typical organic pollutants methylene blue,o-chlorophenol and volatile organic compounds?VOCs?.In this paper,p-type semiconductors NiO and Co₃O₄ modified TiO₂ to reduce the bandgap of TiO₂ to improve the absorption of visible light.And the formation of p-n heterojunctions can build internal electric field in composite interface,which improves the electron transfer efficiency and inhibition of photo-generated electrons and holes,thereby enhancing the photocatalytic efficiency of nano-materials.The main contents and results of this paper are as follows:?1?Hydrothermal Synthesis of NiO/TiO₂ composite nanomaterials,the TEM and HRTEM characterization results show that the synthesized NiO/TiO₂ photocatalyst is a size-uniform and structure-stable rod-shaped nanomaterial with an average diameter of180nm,101 crystal face of titanium dioxide type TiO₂ and 200 crystal face of NiO.are mainly exposed.The band gap value was 2.97eV by DRS characterization,and the E_FBB of the flat band potential was 0.56eV by electrochemical test.The band structure and the heterojunction structure of the composite were analyzed by DRS and electrochemical measurements.?2?Hydrothermal Synthesis of NiO/TiO₂ composite nanomaterials was evaluated by photocatalytic degradation of methylene blue solution.Comparing the diffirent composite ratios of as-prepared nanomaterials in the degradation of methylene blue solution,the NiO/TiO₂?1/6?shows the highest efficiency and the degradation rate of150min 93.8%.The In-situ infrared technology was used to monitor the reaction intermediates of degradation of gaseous toluene by NiO/TiO₂ composite nanomaterials.The photocatalytic oxidation of toluene was also analyzed.The degradation of toluene by NiO/TiO₂ catalyzed by NiO/Formic acid/benzaldehyde?Chain carboxyl/carbonyl/aldehyde/methyl compound?CO,CO,H₂O;?3?Hydrothermal Synthesis of Co₃O₄/TiO₂ composite nanomaterials,the SEM,TEM and HRTEM characterization results show that the synthesized Co₃O₄/TiO₂photocatalyst is a size-uniform and structure-stable rod-shaped nanomaterial with an average diameter of 200nm,101 crystal plane of titanium dioxide type TiO₂ and 311crystal plane of NiO.are mainly exposed.And Co₃O₄ quantum dots were uniformly distributed on the surface of nanorods with an average diameter of 5nm about.The band gap value was 2.26eV by DRS characterization,and the E_FB of the flat band potential was 0.47 eV by electrochemical test.The band structure and the heterojunction structure of the composite were analyzed by DRS and electrochemical measurements.?4?The photocatalytic performance of Co₃O₄/TiO₂ composite nanomaterials was evaluated by photocatalytic degradation of methylene blue and o-chlorophenol solution.The material of Co₃O₄/TiO₂?2%?shows the highest efficiency with the 150min degradation rate of 96%for methylene blue and 90min degradation rate of 84%for o-chlorophenol.