Study On The Structure And Performance Of Doped Modified Titanium Dioxide Photocatalytic Powder And Coating

Semiconductor photocatalysts can directly use sunlight for photocatalysis without secondary pollution,making them an ideal material used in the field of environmental pollution control.Among them,TiO2 has the characteristics of high light stability,good chemical properties,non-toxicity,low cost,high photocatalytic efficiency,etc.,and has received extensive research and attention at present.However,the large forbidden band width of TiO2 and the rapid recombination of electrons-holes cause its own defects such as low quantum yield and limited excitation wavelength,which restricts the photocatalytic performance of TiO2 and affects its practical application..In recent years,improving the photocatalytic performance of TiO2 materials through element doping technology has become an effective way among many methods.This thesis improves the performance of TiO2 photocatalytic purification of dye wastewater by doping with metal elements Ce,Cu and non-metal element N.Firstly,pure TiO2,Ce-TiO2,Cu-TiO2,and Cu/N-TiO2 ternary composite photocatalyst powders were prepared by hydrothermal synthesis,and different Ce and Cu contents,different Cu/N ratios and single doping were investigated.The influence of the microstructure and photocatalytic performance of the hetero and co-doped TiO2;then,the Cu/N-TiO2 photocatalytic coating was prepared by coating method/screen printing and laser sintering process,and the effect of laser sintering power and the number of screen printing layers was studied.The effect of coating structure and performance;finally,in order to explore more modification and doping methods,the experiment used NH3/He and N2/He low-temperature plasma to further modify the TiO2-based composite photocatalyst,and studied The influence of different plasma gas relative material microstructure,optical performance and photocatalytic degradation efficiency of dye wastewater.The results show that:(1)The photocatalytic performance of binary composites prepared by doping with different Ce elements is improved compared with pure TiO2,and the reaction efficiency first increases with the increase of Ce content,but excessive Ce doping will Dispersed in the form of CeO2 on the surface of the sample to weaken the photocatalytic activity;the doping of metal Cu element will increase the visible light absorption capacity of the TiO2 sample,and the photocatalytic performance will be improved.Moreover,when the mass fraction is greater than 0.1%,Due to the high specific surface area and special micropore morphology of Cu-TiO2 sample,its dark adsorption performance is significantly improved,and the methyl orange solution will be purified by adsorption.This significant dark adsorption capacity may be due to the large specific surface area of the Cu-TiO2 sample and the special microscopic shape with large nanopores.The photocatalytic performance of the TiO2 sample co-doped with metal Cu element and non-metallic N element is better than pure metal doping.It is mainly due to the synergistic effect of Cu and N elements that the particle size of the sample is significantly reduced,the visible light absorption capacity is also enhanced,and the band gap is reduced.In addition,the metal Cu+ions act as electron traps in the sample,reducing TiO2 electron-hole recombination,and improving The separation efficiency is improved,and the photocatalytic activity of the Cu/N co-doped TiO2 sample has good repeatability.After eight consecutive cycles,the photocatalytic efficiency under visible light conditions can still reach 94.3%.(3)For Cu/N-TiO2 coating prepared by coating method combined with laser sintering,it is found that the photocatalytic performance of the coating first increases and then decreases with the laser sintering power.The best performance is obtained at 50W,too high or too low power will affect its morphology;in addition,the coating The photocatalytic activity of the layer gradually increases with the increase of the number of screen printing layers,and tends to be stable when it reaches 5 layers(thickness>55μm);(4)The low-temperature plasma treatment modification experiment found that NH3/He or N2/He.After He plasma treatment,there will be part of nitrogen in the sample,and NH3/He plasma treatment has better nitrogen doping effect than N2/He plasma treatment.Plasma modification technology can create more reaction activity on the catalyst surface.The site accelerates its catalytic reaction,thereby enhancing the ability of photocatalytic degradation of dye wastewater.