Study On Photocatalytic Hydrogen Evolution From Glycerol Solution Over TiO₂and ZnO-based Nano Materials

The P, Bi doped TiO₂nanoparticles were firstly prepared by the sol-sel method,and using those nanoparticles as the precursor prepared P, Bi doped TiO₂nanotubesby hydrothermal process. Their pore distribution, crystal structure, surfacecompositions, photo absorption properties were investigated by techniques of N2adsorption-desorption, XRD, FT-IR，FT-Raman, TEM, and UV-Vis DRS. And theas-prepared nanoparticles and nanotubes were used as photocatalysts forphotocatalytic H2production from glycerol solution, the mechanism of reaction wasalso discussed.Experimental results showed that, the P, Bi doped TiO₂nano materials displayedhigh photocatalytic activity not only under the UV irradiation but also undersimulated-solar irradiation. In addition, the nanotubes because of its special structuredisplayed higher activitiy than the nanoparticles. The2%Bi-doped TiO₂shows amaximum H2production rate of1838μmol/h/g under UV irradiation and209μmol/h/gunder simulated-solar irradiation, respectively.Then, a series of ZnO/ZnS core/shell nanorods with different ZnS/ZnO molarratios was synthesized via a new water bath route. Their pore distribution, crystalstructure, surface compositions, photo absorption properties were investigated bytechniques of N2adsorption-desorption, XRD, XPS, SEM, TEM and UV-Vis DRS.The as-prepared nanorods were used as photocatalysts for photocatalytic H2production from glycerol solution. The mechanism of growth and reaction werediscussed.These core/shell nanorods whose diameter are about100nm and whose lengthrange from a few hundred nanometers to several micrometers are formed by coatingZnO nanorod with a layer of porous ZnS shell mainly consisting of crystals about12nm in diameter. The deposition thickness of the ZnS shell layer strongly affectedthe morphologies, surface area, structure, photo absorption and photocatalyticperformance of the ZnO/ZnS core/shell nanorods. The as-prepared ZnO/ZnScore/shell nanorods exhibited a higher photocatalytic activity for H2evolution fromglycerol/water mixtures than the bare ZnO nanorods under the same conditions.Themaximum H2production was2608.7and388.4μmol/h/g under UV and solar-simulated light irradiation, respectively. The deposition thickness of the ZnS shell andthe interaction between the ZnO rod and ZnS shell and the core/shell structure with n- p heterojunction were found to play a key role in their optical and catalyticperformance.