Study On Doped And Intercalted Layered Trititanate For Efficient Photocatalysis

With the development of human society, energy crisis and environmentalpollution have become a series of problems. The semiconductor-based photocatalysishas attracted widespread attention, which provides an effective approach to solve suchproblems, and the preparation of visible-light-active photocatalysts is of greatimportance. Layered titanates have good photocatalytic activity, functional cationic orappropriate semiconductor can be inserted into their interlayer to fabricate aheterojunction, which not only expand the light response of materials to the visiblelight but also increase the separation rate of the photogenerated carriers.In this dissertation, H2Ti3O7, a titanate layered compounds with a highphotocatalytic activity, has been used to prepare modified nanocmoposites. Thephotocatalytic nanocmoposites have been successfully prepared using Ti3O72-nanosheets with Cu2+, Fe2O3and CdS as building blocks via an exfoliation-restackingroute. The as-prepared cmoposites were investigated by means of XRD, SEM, TEM,UV-Vis DRS, XPS, N2adsorption-desorption isotherms and other technologies. Thephotocatalytic activities of these cmoposites were also evaluated.Firstly, novel mesoporous Cu-Ti3O7nanohybrid was assembled by the negativeexfoliated Ti3O72-nanosheets and simple Cu2+cations. It was revealed that the presentnanohybrids are mesoporous with specific surface areas of about182m2/g. Theintercalated nanohybrids exhibit good photocatalytic activities in the degradation ofmethylene blue under visible-light irradiation (λ≥420nm, from a filtered300W Xelamp). The superior photocatalytic performance is predominantly attributed to Cu2+,which effectively adjust the band structure of the semiconductor, reduced the width ofband gap, expanding the scope light response of the material.Secondly, Fe2O3sol was used as the positively electronical guest nanoparticles toprepare Fe2O3-H2Ti3O7. It was observed that the Fe2O3-H2Ti3O7nanohybrid has apillared height of2.06nm, a specific surface area of165m2/g and an average porediameter of4.9nm. The mesoporous material exhibits high photocatalytic activity inthe photocatalytic degradation of methylene blue under the visible light irradiation.The enhanced performance is originated from the stronger electronic couplingbetween the host and the guest in the heterojunction, and thus from the extended absorption spectral range to the visible light.Finally, CdS is a good visible-light active. Pillared CdS-H2Ti3O7nanohybrid wasprepared through the restacking of the Ti3O72-nanosheets in the presence of CdS guestnanoparticles. The as-prepared nanocomposite is mesoporous with an interlayeredgallery of1.92nm and a hierarchical structure with a specific surface area of about90m2/g and an average pore diameter of of4.6nm. Due to the synergistic effect, thenanohybrid exhibits high photocatalytic activity and good recurrence stability in theH2evolution from water splitting. Its H2-evolution rate was1523μmol/h/g under a300W Xe lamp irradiation, which is36times that of the bare H2Ti3O7and13timesthat of the bare CdS.