Jianling Zhang

Time‐Dependent Aggregation‐Induced Enhanced Emission, Absorption Spectral Broadening, and Aggregation Morphology of a Novel Perylene Derivative with a Large D–π–A Structure

Strong aggregation-caused quenching of perylene diimides (PDI) is changed successfully by simple chemical modification with two quinoline moieties through C=C at the bay positions to obtain aggregation-induced enhanced emission (AIEE) of a perylene derivative (Cya-PDI) with a large π-conjugation system. Cya-PDI is weakly luminescent in the well-dispersed CH(3)CN or THF solutions and exhibits an evident time-dependent AIEE and absorption spectra broadening in the aggregated state. In addition, morphological inspection demonstrates that the morphology of the aggregated form of Cya-PDI molecules changed from plate-shaped to rod-like aggregates under the co-effects of time and water. An edge-to-face arrangement of aggregation was proposed and discussed. The fact that the Cya-PDI aggregates show a broad absorption covering the whole visible-light range and strong intermolecular interaction through π-π stacking in the solid state makes them promising materials for optoelectric applications.

TiO2/T-PVA Composites Immobilized on Cordierite: Structure and Photocatalytic Activity for Degrading RhB Under Visible Light

AbstractA novel immobilized visible light-active photocatalyst (TiO2/polyvinyl alcohol after thermal treatment (T-PVA)/cordierite honeycomb (CHC)) was successfully prepared by a simple and convenient method combining sol–gel and thermal treatment using tetrabutyl titanate (TBOT) as the titanium source, polyvinyl alcohol (PVA) as the precursor of conjugated polymer, and CHC as the support. The synthesized photocatalyst was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy, and field emission scanning electron microscopy. The results showed that PVA was dehydrated to produce conjugated unsaturated T-PVA. The T-PVA not only extended the response spectrum of TiO2 to visible light region, but also strengthened the adhesion of TiO2 to CHC. The TiO2/T-PVA/CHC showed both outstanding adsorption properties and excellent photocatalytic performance under visible light on the decolorization of Rhodamine B. Over eight cycles, the photocatalyst continued to maintain perfect photocatalytic activity, showing good stability. FigureSchematic illustration of TiO2/T-PVA/CHC composite photocatalyst

Study of the Thermal Decomposition Behavior of Poly(vinyl alcohol) with NaHSO4

The thermal decomposition behavior of poly(vinyl alcohol) (PVA) with NaHSO4 at 280∼290°C as well as the optical characteristics and the thermal stability of the resulting thermally decomposed PVA were investigated by means of UV-Vis spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The results suggest that (1) the elimination reactions of side groups in PVA with NaHSO4 can occur under our conditions resulting in formation of carbon–carbon double and triple bonds; (2) most of the carbon–carbon double bonds were conjugated; (3) the PVA thermally treated with NaHSO4 could absorb light in the region of 190∼600 nm; (4) the thermal stability of the resulting PVA was better than that of PVA without thermal treatment; and (5) compared with the thermal reaction of PVA without NaHSO4, the addition of NaHSO4 can promote the thermal elimination of side groups of PVA.

4,4′,4′′-Triaminotriphenylamine-based porous polyimide as a visible-light-driven photocatalyst

Aiming to develop a visible-light-driven polymeric photocatalyst that can be fabricated by an easy-to-scale-up polymerization method, a porous polyimide (PPI) with a specific surface area (SBET) of 79.3 m2 g−1 was synthesized by a facile polycondensation of 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) with 4,4′,4′′-triaminotriphenylamine (TPA). UV-vis diffused reflection spectroscopy (DRS), electrochemical analysis, valence band X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculation results reveal that the prepared PPI possesses a narrow band gap (2.04 eV) with the valence band (VB) located at 1.26 V (vs. NHE) and the conduction band (CB) edge at −0.78 V (vs. NHE), clearly indicating the visible light activity of PPI. The photocatalytic performance for the degradation of methylene blue (MB) in water was studied, and the results demonstrate that PPI possesses excellent photocatalytic activity under visible light irradiation. Electron paramagnetic resonance (EPR) and photo-current analyses were used to study the photocatalytic mechanism, which show that PPI has a lot of single electron trapped oxygen and more light-generated electrons. This work may provide a cost-effective, potentially scalable strategy to design and develop a polymeric photocatalyst with continuously tunable photoelectrical properties.