Synthesis And Photocatalytic Properties Of New MoS <2> / TiO 2 Composites

Nowadays, the world is facing serious energy and environmental problems, so it is very urgent to produce a clean and sustainable energy using renewable energy source to solve such problems. Hydrogen energy has been regarded as the most promising alternative energy resource in 21 st century by the majority of scholars around the world. Among various hydrogen production paths, the photocatalytic water splitting technique is increasingly under the spotlight, due to the fact that the system is simple and sustainable, and solar energy could be utilized directly. Hence, the development of the necessary semiconductor photocatalysts has undergone considerable research.In this paper, several high efficient photocatalytic materials were designed to solve the existing problem of photocatalysis, which mainly includes the material of ultrasmall-Ti O2, ultrasmall-Ti O2/Mo S2, Ti O2/few layer-Mo S2 and Embedded Ti O2/single layer-Mo S2. These samples were characterized by XRD, TEM, BET, XPS, PL fluorescence spectrum, UV-vis diffuse absorption spectra and so on. As well as their photocatalytic performance was evaluated by water splitting into hydrogen. The research was mainly composed of the following four parts:(1) The pure ultrasmall-Ti O2 photocatalytic materials was synthesized by solvothermal method, and characterized by XRD, TEM, BET and so on. Its photocatalytic activity for hydrogen evolution was investigated in different dye solution under ultraviolet light irradiation(λ=365 nm, LEDs). The results indicated that the ultrasmall-Ti O2 photocatalyst was more active and stable for hydrogen producing meanwhile in good preference in dye degredation, mainly due to the excellent electron transfer effect of small size nanoparticle and the big BET of mesoporous materials. The optimal material was synthesized under reaction temperature of 130 oC.(2) The Bulk Mo S2 nanosheet loaded with ultrasmall Ti O2 particles was prepared also in a solvothermal route. The photoactivities for H2 production of Ti O2 particles coupled with various different mess of Mo S2 materials were examined also in using methyl orange as sacrificial agent Under ultraviolet light irradiation(λ=365 nm). It has been found that the photoactivity for hydrogen production and photostability of Bulk Mo S2 nanosheet can significantly enhance ultrasmall Ti O2 nanoparticle. Experimental results suggest that the Mo S2 sheet as a novel sandwich nanostructured material could be more beneficial for its best charge carriers transfer and the strong adsorption to the reactant molecules because of high specific surface area and good electric transfer ability. As a result, the activity of hydrogen evolution was promoted.(3)Firstly, we used chemical method exfoliating Bulk Mo S2 to single layer or few layer Mo S2, then we use those exfoliated Mo S2 modifying Ti O2 Quantum Dots,let the Ti O2 stand onto those exfoliated Mo S2 sheet floor. The result seems like we successfully synthesized such special material. Results from characterizations showed that the supporting material Mo S2 sheets can fully support Ti O2 nanpparticles and Ti O2 had a small crystalline size(about 5 nm, Quantum Dots size) which was well dispersed on the floor of Mo S2 sheets. Experimental results show that composite materials process of synthesis didn’t change the Mo S2 structure. It means Mo S2 can transfer the photo-electric of Ti O2 quickly. Ti O2 grains on the sheets structures have a relatively high thermal stability and proper pore diameter allows controlling the size of obtained Ti O2 particles(5-8 nm). The optimal Ti O2 loading content was found to be 3.2 % on the Mo S2 sheet condition.The most important performance of Mo S2 is its ability of Hydrogen evolution in side of the edge. In this part, we successfully put the single Mo S2 embedded into the gap of Ti O2 nanoparticles and also make sure the edge of Mo S2 structure vertically in the compound. Such special structure make the photo-electrical more easily transferred to the egde of Mo S2 sheet. The experimental results suggest based on the part(3) the embedded Ti O2/Mo S2 hybrid materials have more H2 productivity abilities than ever before. And the most important thing is we finally testify single layer Mo S2 can replace Pt as a sufficient co-catalyst in photocatalysis.