Modification Of HTiNbO₅and Its Application In Photocatalytic Hydrogen Production

Semiconductor-based photocatalysis has been attracted widespread attentionbecause of its applications in alleviating the energy crisis and controlling theenvironmental pollution. However, it always suffers from the difficulties of absorbingvisible light and the low quantum yield, which handicaps its practical applicationsand industrialization. Developing new photocatalytic materials or photocatalyticsystems with high performance is one of important issues in photocatalytic chemistry.Aiming for expanding the spectral response of the photocatalysts and for improvingthe solar photocatalytic efficiency, this paper adopts the strategies of dopingheteroatoms to modify the electronic structure, and introducing a secondsemiconductor to fabricate a heterojunction to suppress the recombination ofphotogenerated eletrons and holes. Nonmetal-doped HTiNbO₅and TiO₂/HTiNbO₅pillared nanohybrids have been prepared and characterized by means of XRD,TG-DSC, FE-SEM, HR-TEM, XPS, UV-Vis DRS, photoelectrochemicalmeasurements and so on. The relationships between structures and properties of theas-prepared materials have been investigated, and the application in photocatalytichydrogen production has been explored in this dissertation.Firstly, KTiNbO₅was obtained by solid state reaction, and then exchanged withacid to produce protonated titanoniobate HTiNbO₅. The exfoliation of titanoniobatenanosheetswas achieved by reacting the proton titanoniobate HTiNbO₅withtetrabutylammonium hydroxide. In the materials of doping N and S, it happenedhybridization between the N and O or S and O, which narrowing the band gap ofKTiNbO₅. For the eHTiNbO₅of doping N, we can observe a new obsorption during310-370nm in the spectrogram of UV-Vis, indicating the formation of new energylevel.The nanocmoposites of the layered compound pillared with not only overlayspectral response range of the host and the guest, but also raise the photocatalyticefficiency by separating the photo-induced carriers. In this dissertation, TiO₂/TiNbO₅mesoporous pillared nanocmopositeswas prepared via anexfoliation-restacking route. Their interlayer expansions were about1.55nm, after250℃treatment, the subject and the guest contact more closely, thus improve thephotocatalytic activity. The hydrogen prodution rate of it is230μmol/g/h, afterloading5wt%Pt on it, the hydrogen prodution rate reached4982μmol/g/h, which is20.7times higher than TiO₂/TiNbO₅.