Studies On The Synthesis Of TiO₂ Nanocomposites And The Photocatalytic Performance

With the rapid development of modern industry,the problem of environmental pollution has become increasingly prominent.As a new technology for degrading pollutants,photocatalytic technology has received more and more attention because of its low energy consumption and wide application range.Due to its advantages of non-toxicity,stability,high corrosion resistance,biocompatibility,and low cost,TiO₂ is more widely used in photocatalytic applications.However,the two defects in the TiO₂catalyst limit its application prospects in the field of photocatalysis.The first is that its photoelectron-hole recombination rate is faster,which will lead to a decrease in its reactivity.Second,it does not respond to visible light（due to its wide bandgap 3.2 eV）,which leads to a lower utilization of sunlight.In order to make better use of the photocatalytic ability of TiO₂,some processing techniques will be used to modify its surface.Commonly used materials are composited with other materials,and the excellent properties of other materials are combined to improve the photocatalytic performance of the catalyst.In this paper,three TiO₂ nanocomposite photocatalysts were designed from the perspectives of reducing the photoelectron-hole recombination velocity,increasing the specific surface area of??the catalyst,and reducing the band gap energy of the catalyst.The SEM,TEM,XRD,Raman,Uv-Vis and XPS were used to design the photocatalysts.The microscopic morphology,lattice structure,crystal shape,texture properties,band gap,and chemical state of the material surface of the material were characterized,and the photocatalytic performance of the material was tested by photocatalytic degradation and photocurrent,and summarized as follows:（1）Reduced graphene oxide-titania composite photocatalyst:RGO/TiO₂ was prepared by using a simple hydrothermal method to compound graphene oxide with TiO₂ nanoparticles（NP）.The principle of this experiment is to use the interface effect between graphene and TiO₂ nanoparticles and the high conductivity of graphene itself to increase the electron transfer rate while lowering the band gap energy of the catalyst,so as to improve the photocatalytic performance.RGO/TiO₂ with a doping content of 25%has the best photocatalytic efficiency,and its ability to adsorb organic matter and photocatalytically degrade organic substances are higher than other catalysts,and it has high recycling performance.（The degradation rate after degrading methyl orange by 30cycles can still reach 93%）（2）Titanium dioxide nanoparticle-cerium dioxide nanorod composite photocatalyst:In the photocatalytic experiment,the specific surface area of the catalyst is an important factor that determines the performance of the catalyst.In this experiment,a new type of titania composite catalyst was prepared by using a self-prepared high specific surface area cerium dioxide nanorod through a simple hydrothermal method to load TiO₂nanoparticles（NP）onto the surface of CeO₂ nanorods.This catalyst exhibits two excellent properties,excellent photocatalytic performance and excellent heavy metal ion adsorption performance.When the mass ratio of TiO₂ to CeO₂ reaches 30%in the experiment,the prepared catalyst has the best performance.It shows good performance in photocatalytic degradation of rhodamine B and adsorption of heavy metal ions in water.（3）Cadmium sulfide nanoparticles-titanium dioxide nanorod composites Photocatalysts:Due to their different bandgap energies,various semiconductors lead to different responses to sunlight.In this experiment,CdS nanoparticles-TiO₂ nanorod composites were prepared by hydrothermal method using the advantages of low bandgap energy of CdS（2.42 eV）.Due to the reduced bandgap energy,the present catalyst increases its light-absorbing ability in the visible light range and improves its light energy utilization.Its photocatalytic performance under sunlight is greatly improved,and it has good photocatalytic performance for methyl orange solution.（2times more photocatalytic performance than pure TiO₂）...