The Design, Preparation Of LDHs Based Two-Dimensional Confined Co-intercalated Composites And Its Photoelectric Performance

Layered double hydroxides (LDHs) are a class of typical two-dimensional laminar nanomaterials. It has developed into various intercalated structure functional material due to the ion exchange capability, which have been widely used in the fields of optical, electric,magnetic, catalysis, and biomaterials. In addition, the intercalated molecules will show some novel performance subjected to the two-dimensional confined effect of LDHs, which is in favour of developing a new type of functional material.In this dissertation, a series of organic electron donor/acceptor anions are selected and intercalated into the LDHs by the hydrothermal co-intercalation method, obtained the inorganic/organic materials with optoelectronic conversion effect and photocatalytic performance. The luminous intensity of the optical molecule is improved when it is intercalated into the LDHs, and the co-intercalated LDHs shows fluoresecence detection properties. The electron donor/acceptor polymers are encapsulated into LDHs interlayers by the co-assembly method,achieving the orderly arrangement of polymer molecules and the improvement of photoelectric performance. The main contents are as follows:1. The preparation of DAS(x%)-DNS/LDHs. The 4,4-diaminostilbene-2,2-disulfonate (DAS) and 4,4-dinitro-stilbene-2,2-disulfonate (DNS) anions with arbitrary molar ratios are successfully co-intercalated into Zn2Al-LDHs. The DAS(50%)-DNS/LDHs composite exhibits the broad UV-visible light absorption and fluorescence quenching, which is a direct indication of photo-induced charge transfer(PCT) process. This is confirmed by the matched HOMO/LUMO energy levels alignment of the intercalated DAS and DNS anions, which is also compatible for that of water splitting. Then the DAS(50%)-DNS/LDHs composite is fabricated as photoanode for the photoelectrochemical water splitting, achieving well performance with excellent stability.2. The preparation of CuPcTS-PTCB(x%)/LDHs. The organic electron donor/acceptor anions: copper phthalocyanine-3,4',4 " ,4'''-tetrasulfonate (CuPcTS) and 3,4,9,10-perylenetetracarboxylate (PTCB)are successfully co-intercalated into the Zn1.5Al-layered double hydroxides (LDHs) (CuPcTS-PTCB(x%)/LDHs, x is the percentage ratio of PTCB) to form a new type of layered nanocomposites. The similarity of CuPcTS and PTCB anions in shape and size is benefit for the photo-induced charge transfer (PCT) process. The HOMO/LUMO energy levels of the co-intercalated CuPcTS/PTCB anions detected by cycle voltammetry are matched and coupled as the electron donor and acceptor within the interlayers for the PCT process. The co-intercalated composites exhibit broad optical absorption in visible light region, which is in favor of the effective utilization of solar energy for photocatalysis. The CuPcTS-PTCB(49.75%)/LDHs with excellent stability showes preferential better degradation rate for anionic dyes in comparison to the cationic ones under visible light illumination, due to the hydrophilic positively-charged LDHs monolayers in this new nanocomposite. This novel inorganic/organic nanocomposite photocatalyst exhibits potential prospective application in environmental protection.3. The preparation of PBS(x%)-DES/LDHs. 2-Phenylbenzimidazole-5-sulfonate (PBS) is immobiled into the interlayers of Zn2Al-LDHs by co-intercalating with 1-decane sulfonate (DES) anions. The fluorescence dependance on the molar concentration (x%) of PBS is investigated and the PBS(15%)-DES/LDHs composite exhibits the optimal violet luminescence at 402 nm. Then the PBS(15%)-DES/LDHs composite thin films are fabricated by solvent evaporation method. Moreover, the composite thin film exhibits rapid selective detection for nucleotides triphosphate (AXP, GXP, CXP and UXP) with fluorescence changes,which is expected to be prospective for sensing the nucleotide molecules at the simulated physiological conditions. The origin of the luminescence enhancement is investigated and attributed to the extensive hydrogen bonding interaction between the intercalated PBS and nucleotides.4. The preparation of PCDTBT and CN-PPV co-assembly film. The neutral polymer molecules PCDTBT (electron donor) and CN-PPV(electron acceptor) are co-assembled within LDHs nanosheets to form a novel two-dimensional confined (PCDTBT@CN-PPV/LDHs)n UTFs.The (PCDTBT@CN-PPV/LDHs)n UTFs film exhibits broad absorption in the visible light region, which is beneficial to the absorption of light.The energy level of interlayer PCDTBT and CN-PPV is coupled and matched for photo-induced charge transfer (PCT) process, which is the reason of (PCDTBT@CN-PPV/LDHs)n UTFs fluorescence quenching.As a novel photodetector, the co-assembled UTFs-20 performed a high on/off switching ratio (?120),a fast response, a short recovery time(lower than 0.1 s),and excellent wavelength and light intensity dependence. The flexible UTFs-20 were also fabricated, exhibiting excellent photodetector properties and outstanding stability. This novel two-dimensional confined thin film has potential applications in optical detector.