Molecular Modification Of Carbon Nitride/Titanium Dioxide Composites And The Study Of Visible Catalytic Properties

Human development has produced two major problems: Energy shortage and environmental pollution have always attracted the attention of scientists both at home and abroad.For decades,researchers have done a lot of research and are committed to developing a clean and efficient photocatalyst to solve the upcoming energy crisis and increasingly serious environmental problems.Semiconductor photocatalyst titanium dioxide has been used to solve these two problems.Titanium dioxide has excellent photo,thermal and chemical stability as a photocatalyst,low cost,non-toxic and other advantages.However,there are some limitations: on the one hand,it can only respond under UV light.On the other hand,the photogenerated holes and electrons on the titania catalyst are easy to recombine.In addition,the reuse of the catalyst needs to be solved to avoid environmental pollution.The graphite phase carbon nitride has a ?-conjugated structure,can absorb visible light,also has a fast electron transfer rate,and effectively suppresses the recombination of photogenerated hole-electron pairs.The composite catalysts prepared from these two materials not only play a complementary role,but also have a synergistic effect with each other.Therefore,this article first prepared a small molecule modified carbon nitride CNX,and then stripped into carbon nitride nanosheets(CNX-NSs)similar to the two-dimensional planar structure of graphene,with a larger ?-conjugated structure,visible light response range Increased,it also has a higher specific surface area and better water dispersibility.Then colloidal TiO2 was prepared by sol-gel method.Finally,nanocomposite TiO2/CNX-NSs were prepared by direct interface assembly.TiO2/CNX-NSs/Pt was prepared by photoreduction method.It was found that when the content of TiO2 in TiO2/CNX-NSs was 25%,the activity of hydrogen production was up to 138.4 ?mol/h.The apparent quantum yield AQY reaches 7.04% at a wavelength of 450 nm.The catalyst can be recycled for 5 times,producing hydrogen for 5 h per cycle.The prepared catalyst broadens the range of visible spectrum response,and at the same time effectively reduces the chance of photo-hole-electron recombination and improves the recycling capacity of the catalyst.The {001} facets TiO2 was prepared by hydrothermal method,and it was used to degrade the dye Rh B under visible light,and the degradation rate was found to be 68.5% in 30 minutes.The degradation rate of the LPT precursor as a blank control was only 5.7%.Obviously see the advantages of {001} facets TiO2 in the degradation of dyes.After TiO2 and CNX-NSs were prepared as a composite material.finally the {001} facets TiO2/CNX-NSs was loaded with Pt at 0.5 wt%,hydrogen production under visible light was performed.It was found that the {001} facets TiO2/CNX-NSs/Pt with 18% TiO2 had the best hydrogen generation activity as high as 57.05 ? mol/h under visible light.The hydrogen production of TiO2/CN-NSs/Pt was reduced by half compared with that of the sample,which it is hydrogen production only have 27.04 ? mol/h.And by FTIR and XRD characterization found no changes in the structure before and after hydrogen production,the catalyst performance is stable.