Preparation Of Visible-light Catalyst By Polyvinyl Alcohol And Inorganic Semiconductor

Polyvinyl alcohol(PVA)/TiO2 nanocomposites were prepared by adsorbing a small amount of PVA on the surface of TiO2 via a facile adsorption method.PVA derivatives(DPVA)with conjugated structure were obtained by dehydration of sulfuric acid.The DPVA/TiO2 nanocomposites were synthesized by treating PVA/TiO2 using sulfuric acid.The obtained DPVA/TiO2 nanocomposites were characterized by X-ray diffraction(XRD),Fourier transform infrared spectra(FTIR),scanning electron microscopy(SEM),UV-vis diffuse reflection spectroscopy(DRS),and X-ray photoelectron spectroscopy(XPS).The results show that DPVA with the partly conjugated structure was obtained via the water revomal from PVA molecules on the TiO2 surface after the treatment of sulfuric acid.The surface modification of a small amount of DPVA hardly changes the chemical composition,crystalline and crystal size of TiO2 nanopaticles,while obviously improve the optical absorption capacity of DPVA/TiO2 nanocomposites in the visible range.With Rhodamine B(RhB)as a model pollutant,the visible-light photocatalytic activity of the DPVA/TiO2 nanocomposites was investigated by evaluating the RhB decomposition under visible light irradiation.The stability of DPVA/TiO2 nanocomposites was investigated by the cycle degradation of RhB under visible light irradiation in the presence of DPVA/TiO2 nanocomposites.The results reveal that the trace conjugated polymers on the TiO2 surface significantly enhance the visible-light photocatalytic activity of TiO2 nanoparticles.As the DPVA content in the nanocomposites increases,their visible light photocatalytic activity increases first and then decreases,and the nanocomposite with the DPVA and TiO2 mass ratio of 1:200 exhibits the highest visible light photocatalytic activity.The investigated nanocomposites exhibit well visible-light photoctatalytic stability,and the photogenerated holes are thought as the main active species for the RhB photodegradation in the presence of the DPVA/TiO2 nanocomposites.DPVA/Ag3PO4 composites with conjugate structure,was prepared by heat treating PVA/Ag3PO4 prepared by adsorbing a small amount of PVA on the surface of TiO2 via a facile adsorption method.The obtained DPVA/Ag3PO4 composites were characterized and analyzed by the methods including SEM,XRD,XPS and DRS.The results show that Ag3PO4 modified by DPVA is still the kind of spherical particals,and Reunion phenomenon is slightly reduced;The crystal structure of DPVA/Ag3PO4 composites almost do not change;DPVA in the DPVA/Ag3PO4 composites exist conjugate structure and its optical absorption ability has been improved obviously.With Methyl orange(MO)as a model pollutant,the visible-light photocatalytic activity of the DPVA/Ag3PO4 composites and influencing factors(including compound ratio,temperature and time of heat treatment)was investigated by evaluating the MO decomposition under visible light irradiation.The results show that the obtained DPVA/Ag3PO4 composite materials showed optimal photocatalytic activities when the mass proportion of silver phosphate and PVA was 10000:1,heated at 180? for 1h.