Facile Construction Of Mesoporous TiO₂ Based Nanocatalysts Using Modified Collagen Fiber As The Biotemplate And Its Photocatalytic Activity

Collagen fiber(CF)is the main component of abandoned animal biomass resources,which is cheap and easy to obtain.It has special chemical properties and natural mesoscopic structure,and its molecular structure has abundant active groups,which can react with plant polyphenols and Ti4+ or other metal ions.Bayberry tannin(BT)is a natural plant polyphenol extracted from plants.More importantly,abundant ortho-phenolic hydroxyls in bayberry tannin have high affinity toward various metal species.At the same time,the skeleton structure of the benzene molecule has an effective steric hindrance and can be used as an excellent stabilizer to prevent the agglomeration of nanoparticles.So,BT-grafted CF can be an ideal biological template to preparae a series of fibrous TiO2 based nanocatalysts with mesoporous structure.Traditionally,titanium based nano catalysts are mostly used in photocatalysts,but there is always a large band gap and weak photocatalytic activity.The doping of metal ions is often used to improve the visible light photocatalytic activity of TiO2.Based on this,in this paper,we use bayberry tannin grafted collagen fiber as biological template,inorganic metal salts as precursors,synthesized a series of fibrous metal ion doped mesoporous TiO2 photocatalyst.The main research contents are as follows:(1)Ag doped TiO2 mesoporous nanofiber were successful prepared.The fibrous morphology of collagen fiber is mostly preserved during the preparation of Ag-doped Ti02 fibers.It was found that there are optimal Ag doped dosage and calcination temperature,xwhen the calcination temperature was 500 ? and the mole ratio of Ag/Ti was0.2,the Ag0.2/TiO2nanofibers have relative smaller crystal size(7.1 nm)than the pure TiO2(9.7nm),which exhibits higher specific surface area(111.65 m2/g)and lower the band gap(2.446 eV)than the pure TiO2(62.21 m2/g,3.131 eV,respectively),and the degradation rate of MO by the A90.2/TiO2 was92.1%at 40min under visible light irradiation,while that of TiO2 only 4.34%.(2)Bi doped TiO2 mesoporous nanofiber were successful prepared.The well-defined hierarchical morphology of CF was successfully incorporated in Bi doped TiO2 mesoporous nanofiber.After doping Bi,the growth of grain size were inhibited and the specific surface area of the catalystswere increased.When the calcination temperature at 500?,molar ratio of Bi/Ti at 0.02,the absorbance wavelength of the Bi0.02/TiO2 reached 448 nm,the degradation rate of Methylene Blue reached to 93.1%at 60min under irradiation of visible light,while that of TiO2 is 41.9%.(3)Sn doped TiO2 mesoporous nanofiber were successful prepared.When the preparation process of Sn doped mesoporous TiO2 nanofiber,it was found that a trace amount of Sn can lead to the transition of anatase to rutile phase.For example,when the calcination temperature at 500 ?,the Sn0.03/TiO2 preserve the anastase phase and rutile phase,and the red shft of the absorption edgewavelength of the Sn0.03/TiO2 exhibited the highest of 426nm and the band gap energy was reduced to 2.911 eV.Furthermore,the calcination temperature and the content of Sn will effect the amount of rutile phase,an suitable content of rutile phase will result in higer photoassisted catalytic activity.The results showed that the Sn0.03/TiO2-500? nanofiber exhibited the highest photocatlytic activity,the degradation rate of RhB reached99.1%under visible light irradiation for 80 min,while that of pure TiO2 is 44.5%.