The Photocatalytic Performance For H₂Production From Glycerol Solution Over Modified TiO₂Nano Materials

A series of MxO(M=Bi, Zn, Ag) doped and MxO(S) codoped-TiO2semiconductors were synthesized by a sol-gel method. Meanwhile, Ag2S-TiO2semiconductors were synthesized by an ion exchange process. Their crystal structure and photo absorption properties were investigated by SEM, TEM, XRD, FT-Raman, FT-IR, XPS, and UV-Vis DRS. The mechanism of photocatalytic H2production from glycerol solution was also disussed, in which the as-prepared nanoparticles were used as photocatalysts.The results showed that the doping Bi and Zn existed as the formation of Bi2O3and Zn2TiO4, and the S existed as SO42-. The doping elements could deacrease the diameter of the TiO2nanoparticles. TiO2with the doping metallic and nonmetal elements showed an extension of light absorption into the visible region, which mainly originated from the formation of new energy level. The addition of SO42-could improve photocatalytic activities by increasing the acidic sites of catalyst. The doping metallic and nonmetal elements strongly affected photocatalytic performance of the TiO2nanoparticles. Under the same conditions, the TiO2nanoparticles with the doping of Bi and S exhibited a higher photocatalytic activity for H2evolution from glycerol/water mixtures than the bare TiO2nanoparticles. The3%Bi-doped TiO2had a maximum H2production rate of1311.7under UV irradiation and140.4mol·(h·gcat)-1under simulated-solar irradiation, and3%Bi,S-codoped TiO2had a maximum H2production rate of1514.9and190.2mol·(h·gcat)-1.The doped Ag existed as the form of Ag2O, and it could be transformed into Ag2S through the ion exchange process. The doping Ag could deacrease the diameter of the TiO2nanoparticles. TiO2nanoparticles with the doping Ag showed an extension of light absorption into the visible region, which mainly originated from the formation of new energy level. The doping Ag2O (or Ag2S) strongly affected photocatalytic performance of the TiO2nanoparticles. Under the same conditions, the TiO2nanoparticles doped with Ag exhibited a higher photocatalytic activity for H2evolution from glycerol/water mixtures than the bare TiO2nanoparticles. The5%Ag2O-doped TiO2had a maximum H2production rate of10721.9under UV irradiation and111.5mol·(h·gcat)-1under visible light irradiation, and5%Ag2S-doped TiO2had a maximum H2production rate of5049.2and 178.5mol·(h·gcat)-1.