Study On Photocatalytic Properties Of Fe-TNAs On Benzene Series Based On The First Principle

In recent years,due to the serious problem of volatile organic compounds（VOCs）pollution in the micro-environment,people pay more and more attention to it.The most common toxic VOCs are benzene,formaldehyde,nitrobenzene,etc.When the VOCs concentration exceeds a certain value,they will directly endanger people’s health,and it is the main precursor of PM2.5.Semiconductor titania is cheap,non-toxic,easily prepared,chemically stable,has strong corrosion resistance,electrons on the conduction band,and holes on the valence band have strong oxidation-reduction ability.It has been widely used as a photocatalyst for the research and practice of photocatalytic degradation of VOCs in microenvironments.However,titanium dioxide has a large band gap and cannot be activated by visible light excitation,and there is a problem that the utilization of natural light is low.Therefore,it is one of the most active research directions both at home and abroad in recent years that the enhancement of TiO₂ photocatalytic material response to visible light by doping and modification.In this paper,experimental studies and simulations on the photocatalytic degradation of volatile organic compounds（VOCs）using titanium dioxide nanotubes are reviewed.Based on a large number of literature references,doping methods and the doping methods have been calculated based on the first principles of density functional theory.The effect of Fe doping on the energy band structure and density of states of anatase Fe/TiO₂（001）,the adsorption energy of benzene molecules and toluene molecules on different kinds of doped Fe/TiO₂（001）and the adsorption sites.The calculation results show that the surface gap doping is more conducive to the reduction of the band gap of TiO₂ than the doping of the TiO₂,and when the doping concentration is 6.122%,the band gap can be reduced by up to 59.3%compared with the pure TiO₂.The doping concentration ranged from 2.083%to 4.167%,and the potential of photogenerated holes ranged from 1.82 to 2.31 eV.The surface Fe-doped TiO₂ was highly oxidizing;the C₆H₆ and C₇H₈ molecules were anatase-type Fe/TiO₂（001）.The surface is mainly adsorbed horizontally.When co-existence of gap doping and doping doping,the adsorption energy of Fe/TiO₂（001）surface to the molecule is large.In the range of research concentration,the adsorption is increased with the increase of Fe atom doping concentration.It does not show a tendency to decrease like the band gap,but when the atomic concentration of Fe atoms is 4.082%,that is,the adsorption energy of benzene and toluene is the largest when they are doubly atomized,which are 2.882eV and 3.921eV,respectively,and the increase is At 63.2%and 47.4%,during the adsorption process,the C atoms on the benzene ring in the benzene and toluene molecules bond with Fe atoms and Ti atoms in TiO₂ to form chemical adsorption.Both gas molecules are more easily adsorbed on the TiO₂ surface.For the Fe doping,the adsorption energy is:C₇H₈>C₆H₆.In order to verify the above calculation results,the Fe₂O₃/TiO₂ composite nanomaterials were used to investigate the dark environment adsorption and photocatalytic degradation of the benzene series on the microenvironment.Experiments show that in the dark environment,when the composite titanium dioxide nanotubes adsorb two kinds of single gases at the same time,the adsorption rate of the two gases is very close,but when the mixed gas of benzene and toluene is adsorbed,the adsorption rate of toluene is obviously higher than that of benzene.The adsorption rate,up to 3.4 times,can be seen in the mixed gas,the adsorption of toluene on benzene inhibited,there is more obvious competitive adsorption.For a single gas benzene（toluene）adsorption rate,when the residence time increased from 5 to 15 min when the catalyst dosage was the same,the adsorption rate of benzene and toluene on the TiO₂ nanotubes increased,but the overall increase showed a decreasing trend,and the adsorption rate was average.The increase was 50.43%（48.69%）.By studying the adsorption rate and photocatalytic degradation rate of the mixed gas of benzene and toluene,it was found that the amount of the catalyst was within 1 to 4 pieces,the adsorption rate was proportional to the degradation rate,which could indicate that the preparation had good adsorption morphology.The TiO₂ nanotubes have important implications for increasing the degradation rate.However,when the amount of catalyst reaches 5,the degradation rate decreases due to the increase in the amount of catalytic material in the reaction vessel,which results in partial materials blocking each other from being directly irradiated by light,and the increase in the number of photogenerated holes is little.