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Construction of donor-acceptor type conjugated microporous polymers: a fascinating strategy for the development of efficient heterogeneous photocatalysts in organic synthesis
摘要： Metal-free, visible-light driven, solid organic photocatalysts provide a more green and environmentally friendly alternative to traditional metal-based photocatalysts. Donor-Acceepor (D-A) dyads possess a feature of easy to adjust the photoelectric properties, and enhance their photocatalytic performances. Here we report a fascinating strategy for screening excellent organic porous photocatalysts through oxidative coupling of single D-A based monomer, which has still an important advantage to ensure uniformity of polymer structure except for the inherent characteristics of D-A polymers. According to this strategy, three D-A typed conjugated microporous polymer (DA-CMP) photocatalysts consisting of alternating electron-rich (carbazole) and electron-deficient (benzene, 4,7-diphenyl-2,1,3-benzothiadiazole or anthraquinone) units have been synthesized, and their porosity and photoelectric properties including adsorption, emission, lifetime, optical bandgaps, energy levels and transient photocurrent response as well as photocatalytic activity, were conveniently tuned by selecting different D-A monomers with tunable electron-deficient moiety. These DA-CMPs were exploited as metal-free photocatalysts in the oxidative C-H functionalization reactions in the presence of visible-light and molecular oxygen. They showed excellent photocatalytic activity, extensive substrate adaptability and outstanding reusability, due to combining some key features like permanent porosity, outstanding stability and optoelectronic properties. In addition, the reaction mechanism for DA-CMP photocatalyzed C-H functionalization reactions under visible-light irradiation was investigated in detail. Moreover, to prove in depth the benefits of the heterogeneous photocatalysis, a continuous flow procedure has been conducted with an excellent yield.
关键词： flow chemistry,aerobic reaction,conjugated microporous polymers,C-H functionalization,heterogeneous photocatalysis
更新于2025-09-10 09:29:36
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Simple TiO <sub/>2</sub> Coatings by Sol–Gel Techniques Combined with Commercial TiO <sub/>2</sub> Particles for Use in Heterogeneous Photocatalysis
摘要： TiO2 coatings were obtained by a combination of a sol–gel process with the addition of commercial TiO2 particles (Degussa-Evonik P25). Simple and composite (with P25) sols were deposited by dip-coating on glass plates giving simple and composite coatings. The order of addition of reagents in the preparation of sols, the incorporation of P25 to the sols, and the thermal treatments were analyzed as variables to improve the photocatalytic activity. The samples were completely characterized with respect to the amount of deposited TiO2, the crystal structure (XRD) and the morphology (SEM). The activity of the supported photocatalysts (simple, composite and P25 coatings) was evaluated using 4-chlorophenol degradation and Cr(VI) reduction in the presence of EDTA as model photocatalytic systems. The stability of sols and the photocatalytic activity of the resulted coatings depended strongly on the order of addition of the reagents to obtain the simple sol. Sols prepared by adding the alcohol-water-HCl mixture to the precursor were the simple sols presenting a very good stability that permitted the incorporation of powdered P25 without the addition of additives. The composite coatings prepared from these simple sols were the most active in both photocatalytic systems and also presented the highest resistance to scratch.
关键词： TiO2 Films,Sol–Gel,Heterogeneous Photocatalysis
更新于2025-09-09 09:28:46
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Optimization and modeling of UV-TiO <sub/>2</sub> mediated photocatalytic degradation of golden yellow dye through response surface methodology
摘要： In this article, heterogeneous photocatalysis of golden yellow (GY) dye by Evonik p25 titanium dioxide (PTD) and UV radiations was optimized by using central composite design of response surface methodology. The GY dye photocatalysis was expressed as the function of amount of PTD loading (X1), GY dye initial concentration (X2), and UV irradiance intensity (X3). The optimization of degradation conditions was done by measuring two different responses, that is, color removal (Y1) and chemical oxygen demand removal (Y2). The effect of X1, X2, and X3 were studied in the range 0.5–1.5 g/L, 15–35 W/m2, and 10–30 mg/L, respectively. The quadratic model was suggested for Y1 and Y2. The numerical optimization of results was done via Design Expert software. The predictive results obtained were verified by performing actual experiments. The photodegradation kinetics, total organic carbon disappearance, effect of inorganic salts, and H2O2 concentration on GY dye photodegradation were also studied.
关键词： Titanium dioxide,Heterogeneous photocatalysis,Central composite design,Optimization,Golden yellow dye,Response surface methodology
更新于2025-09-04 15:30:14