Preparation Of Visible-light Photocatalyst With Polyvinyl Alcohol As Main Precursor

A series of high-efficiency visible-light-driven conjugated polyvinyl alcohol derivatives/silver phosphate（CDPVA/Ag₃PO₄）photocatalysts were synthesized via the method of impregnation and heat treatment with PVA as the raw materials.The as-prepared photocatalytsts were characterized by the Scanning electron microscopy（SEM）,X-ray diffraction（XRD）,Raman spectroscopy（Raman）,X-ray photoelectron spectroscopy（XPS）,UV-vis diffuse reflectance spectroscopy（DRS）,Electrochemical impedance spectra（EIS）and Photoluminescence spectroscopy（PL）.The visible-light photocatalytic performances of the CDPVA/Ag₃PO₄ nanocomposites were investigated with methyl orange,phenol,potassium dichromate as the model pollutants.The results reveal that an appropriate amount of CDPVA is conducive to reduce the aggregation of Ag₃PO₄,strengthen the visible-light absorbance and enhance the separation efficiency of photogenerated electrons and holes.Compared with Ag₃PO₄,CDPVA/Ag₃PO₄nanocomposites exhibit a higher visible-light photocatalytic activity and improved antiphotocorrosion performance.The conjugated polyvinyl alcohol derivatives/cuprous oxide（CDPVA/Cu₂O）nanocomposites were prepared via an“in situ”method.The morphology,structure,optical properties and electrical properties of CDPVA/Cu₂O nanocomposites were characterized.The effects of preparation conditions on the visible-light photocatalytic activity of CDPVA/Cu₂O nanocomposites were investigated with phenol as the model pollutant.The results show that the crystal size of Cu₂O fabricated in PVA aqueous solutions is obviously reduced,and a small amount of CDPVA on the Cu₂O surface hardly changes the crystalline of Cu₂O nanoparticles,while dramatically enhances its visible-light absorbance and separation efficiency of photogenerated electrons and holes.The visible-light photocatalytic activity of the CDPVA/Cu₂O nanocomposites increases at first and then decreases with the increase of CDPVA content on the nanocomposites and the prolongation of heat treatment time.CDPVA/Cu₂O nanocomposites show optimal photocatalytic activities when the mass proportion of PVA and Cu₂O is 1:1000,heated temperature is 180℃and the time is 1 h.The conjugated polyvinyl alcohol derivatives/titanium dioxide（CDPVA/TiO₂）nanocomposites were synthesized by precipitation method.The as-prepared photocatalyst were characterized by SEM,XRD,FTIR,XPS,UV-vis DRS and PL.The visible-light photocatalytic performances of the CDPVA/TiO₂ nanocomposites were investigated with Rhodamine B as the model pollutant.The results reveal that CDPVA on the TiO₂ surface hardly changes the crystalline of TiO₂ nanoparticles,while dramatically enhances its visible-light absorbance.Compared with pure CDPVA,TiO₂and g-C₃N₄,the CDPVA/TiO₂nanocomposites exhibit a higher visible-light photocatalytic activity,and its visible-light photocatalytic activity is about 36.0,15.4,2.4 times greater than those of pure CDPVA,TiO₂,g-C₃N₄.Besides,CDPVA/TiO₂ nanocomposites still exhibit high visible-light photocatalytic activity after 10 cycles.A series of conjugated polyvinyl alcohol derivatives/silver/titanium dioxide（CDPVA/Ag/TiO₂）nanocomposites were synthesized via the method of thermal reduction and precipitation with silver nitrate as the raw materials.The morphology,structure and properties of CDPVA/Ag/TiO₂ nanocomposites were characterized.The visible-light photocatalytic performances of the CDPVA/Ag/TiO₂ nanocomposites were investigated with Rhodamine B as the model pollutant.The results reveal that the main chemical composition of CDPVA/Ag/TiO₂ nanocomposites are CDPVA,TiO₂and Ag,an appropriate amount of CDPVA and Ag is conducive to strengthen the visible-light absorbance and enhance the separation efficiency of photogenerated electrons and holes.CDPVA/Ag/TiO₂ nanocomposites exhibit excellent visible-light photocatalytic activity and stability and its visible-light photocatalytic activity is about 1.3 times greater than those of CDPVA/TiO₂ nanocomposites.