| With Environmental pollution and energy shortage global problems seriously increasing, the preparation of novel nanomaterials for environmental pollution and efficient green electrode materials become a hot topic in current research. In this research work, the desired goals are as fellows:(i) decorating chalcogenides on the anodic Ti O2 nanotube(NT) arrays in situ,(ii) investigating the Photocatalytic and Photoelectrocatalytic properties of the as-prepared composite materials,(iii) photocatalytic degradation of organic pollutants and photocatalytic reduction of Cr(VI). Photocatalytic reduction of Cr VI was studied in the presence of Ti O2 nanowire arrays(NWs) with the presendents of low molecular weight organic acids(LOAs). The details are summarized as follows:(1) Mo S2 nanosheet/Ti O2 nanotube(NT) arrays hybrid nanostructure was successfully prepared by a faicle two-step method: the highly-ordered Ti O2 NTs were obtained by anodic oxidization method as template, and then assembly of Mo S2 nanoclusters that consist of few-layer nanosheets via a simple hydrothermal reaction. SEM,TEM,XPS,PL spectra,Mapping and EIS were used to characterize the composite photoelectrocatalysts.The photocatalytic(PE) and photoelectrocatalytic(PEC) performance of the composite catalysts were determined on the Cr(VI) reduction, which certified that the Mo S2 nanosheet/Ti O2 NTs heterostructure shows superior visible-light PEC activity and excellent stability in the cyclic experiment. With the small molecule organic acids adding as a sacrificial agent for holes,, the overall trend of Cr(VI) PE and PEC degradation rates were in the same order as : L(+)-Tartaric acid>oxalic acid>citric acid>malic acid>amber caid. The improved PEC performace of the Mo S2 nanosheet/Ti O2 NTs heterostructure was attributed to three aspects listed below:(i) reduction overpotential, enhanced electron transfer rate on Mo S2, and the p-n junction formed between Ti O2 and Mo S2, which accelerates the effective separation of photogenerated carriers by the internal electrostatic field in the junction region.(2) Assisted by low molecular weight organic acids(LOAs), photocatalytic reduction of CrVI was studied in the presence of Ti O2 nanowire arrays(NWs) under the visible light. Theoritical calculations indicates that the decisive factors for this conversion are the stable adsorption behavior of LOA on Ti O2 and orbital overlapping between the LOA HOMO and Ti O2 LUMO. The orbital configuration interprets that covalent bonds are formed between the LOA and Ti O2. Direct electron transfer occurs from LOA to Ti O2 surface which facilitates the reducing of CrVI. Tartaric acid(TA) is proved to be the optimum organic acid for the surface-catalyzed reduction of CrVI. The TA can be easily excited by the light with wavelength higher than 1033 nm and be broken into two same molecular segments. The molecular segments accelerate the CrVI reduction which follows a two-stage pseudo-first-order kinetics that is slow at initial stage and fast at the second stage.(3)Flower-like In2S3/Ti O2 nanotube(NT) arrays hybrid nanostructure was successfully prepared in a simple hydrothermal method with L(+)-Cysteine and In Cl3 as precursors. The SEM and TEM images showed that as-prepared In2S3 nanosheets stacked on Ti O2 NTs in situ resulting in a flower-like structure coating on the Ti O2 NTs. The results showed that the introduction of narrow band gap In2S3 accelerated the separation efficiency of electron-holes. With low concentration of precursors, the as-prepared composite nanomaterials exhibit a high photocatalytic degradation rate of 4-NP as 95.6%. |
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