Yttrium vanadate coupled with cobalt ferrite nanocrystals for enhanced photocatalytic H2 production under visible light irradiation

Yttrium vanadate (YVO₄) nanocrystals are synthesized by a modified sol-gel route followed by coupling with 4.0–16.0 wt% of cobalt ferrite (CoFe₂O₄) nanoparticles. The synthesized heterostructures were laboured for photocatalytic H₂ generation in a water/glycerol system below visible light in the presence of platinum cocatalyst traces. The addition of CoFe₂O₄ nanoparticles has improved the physicochemical characteristics of YVO₄ in terms of light harvesting and photoinduced charge separation. The 12.0 wt% CoFe₂O₄/YVO₄ indicates the narrowest bandgap of 2.5 eV and the highest visible-light activity with a slight reduction of its surface area from 185 to 168 m² g⁻¹. Moreover, the H₂ evolution rate has augmented utilizing this photocatalyst at 2.557 mmol g⁻¹h⁻¹ compared to 0.044 mmol g⁻¹h⁻¹ over the pure YVO₄. Furthermore, the dose optimization of 12% CoFe₂O₄/YVO₄ at 2.0 gL⁻¹ has endorsed the photocatalytic generation of H₂ to 3.389 mmol g⁻¹h⁻¹ with recyclability of 97% after the fifth cycle.     

One-pot three-component synthesis of tetrahydrobenzo[b]pyrans catalyzed by cost-effective ionic liquid in aqueous medium☆

A simple and efficient method is proposed for the synthesis of tetrahydrobenzo[b]pyrans with aromatic alde-hydes, active methylene compounds, and dimedone using basic ionic liquid catalyst in water. The procedure offers several advantages including short reaction time, good yield, easy procedure, and good recyclability of catalysts, which may be a practical alternative to conventional processes for preparation of 4-hpyrans.     

Solution- and air-recoverable photocatalytic nanofibers by facile and cost-effective electrospinning and co-precipitation processes

While nanostructured materials are of particular academic and practical interest, their recoverability and recyclability have been of paramount industrial and environmental concerns. In the present contribution, co-precipitation was demonstrated as a facile and cost-effective approach to incorporate magnetic sensitivity and enhance the recoverability of nanofibrous materials which were frequently utilized in catalysis, energy and medical applications, etc. In particular, reusable magnetic and photocatalytic hybrid nanofibers were generated by electrospinning and co-precipitation method. First, TiO₂ nanofibers were prepared through sol-gel reaction and electrospinning process. To improve their recoverability, CoFe₂O₄ nanoparticles were decorated onto the nanofibers' surfaces via co-precipitation of cobalt and iron ions in the presence of the nanofibers suspension. Furthermore, the resulting CoFe₂O₄-decorated TiO₂ nanofibers maintained their photocatalytic activity after the modification. When suspended in a solution or spread on a dried surfaces, these nanofibers could be recollected with a magnet. These findings suggested that incorporation of ferromagnetic into the nanofibers maintained their photocatalytic performance and reduced production cost as well as the risk of human and environmental exposure through solution and air.     

整车回收利用率影响因素研究

随着我国汽车保有量的不断增加,报废汽车数量也在逐年攀升,随之而来的报废汽车处置问题愈显突出,因此汽车行业必须积极开展报废汽车的回收利用工作并致力于提高汽车产品回收利用率的研究。通过将整车划分为不同的系统并对各系统的回收利用率及零部件进行对比研究,找出了影响整车回收利用率的关键零部件及主要影响因素。     

Visible-Light-Mediated Amide Synthesis in Deep Eutectic Solvents

In the present study, for the first time environmentally friendly deep eutectic solvents (DESs) are used as reaction media to perform an efficient, simple and straightforward photocatalytic amide synthesis at room temperature using thioacids and amines. This method features mild conditions, a broad substrate scope, high yields (≤99%) under ambient conditions with air and moisture tolerance. Moreover, the applied operationally mild reaction conditions tolerate the presence of several different functional group substituents on the amine counterpart. Finally, the developed approach allows the recycling of the reaction medium and catalyst for at least three consecutive cycles without a significant decrease in the reaction yield.     

Poly (acrylic acid)/polysaccharides IPN derived metal free catalyst for rapid hydrogen generation via NaBH4 methanolysis

Polymeric catalysts have displayed great performance for catalytic hydrogen generation. However, the reported metal free polymeric catalysts for NaBH₄ methanolysis are mainly limited to coating strategy where the catalytic activity fade after few cycles. Herein, we report an interpenetrating polymer network (IPN) strategy for rapid and highly recyclable NaBH₄ catalytic methanolysis to produce hydrogen (H₂) gas. In this study, we prepared poly(acrylic acid)/polysaccharide IPN via Pickering tempted polymerization. The hydrogen generation performance was studied employing different parameters where maximum HGR of 8182 mL H₂ min^?1 g^?1 of CAP. The activation energy Ea, enthalpy and entropy were calculated to be 62.99 kJ mol^?1, 32.25 kJ mol and ?130.92 J mol K^?1, respectively. Above all, CAP kept cyclic performance to 100% even at the 7th cycle. We confirmed the reproducibility of approach with other natural polysaccharides. This was due to strong chain entanglement of IPN synthesis which forces the active sites to stay in place during cyclic catalysis reaction. Thus, the IPN strategy ensures longer catalyst life for catalytic methanolysis of NaBH₄ for H₂ generation.     

Covalently anchored metal complexes onto silica as selective catalysts for the liquid phase oxidation of benzoins to benzils with air

Benzoins are selectively oxidized to benzils in the presence of covalently anchored metal complexes onto silica by stirring in toluene at 100 °C in air atmosphere. Silica functionalized metal complexes have been prepared by the complexation of organically modified silica (imine) with Pd(OAc)₂ (Cat 1), Co(OAc)₂ (Cat 2) and Ni(OAc)₂ (Cat 3). Cat 1, 2 and 3 have been characterized by FTIR, thermal analysis and AAS analysis. Cat 1 was found to be most active, stable and recyclable under the reaction conditions. It was also characterized by SEM and TEM.     

Visible light induced photocatalytic activity of MnO2/BiVO4 for the degradation of organic dye and tetracycline

In this work, α-MnO₂/BiVO₄ nanocomposites with varying MnO₂ contents (0–7 wt%) were successfully prepared via the simple chemical method. The structure, morphology, and optical properties of prepared nanocomposites were studied by various analytical techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–visible absorption spectroscopy, and photoluminescence (PL) spectroscopy. The photocatalytic efficiency of α-MnO₂/BiVO₄ nanocomposites was studied via decomposition of rhodamine B (RhB) and tetracycline (TC) under exposure to visible light (λ ≥ 420 nm). Due to good structure and composite advantages, 5%MnO₂/BiVO₄ (MnBV-5) photocatalyst exhibited superior RhB and TC degradation efficiency to all other samples. In addition, the MnBV-5 photocatalyst showed good stability, and no apparent reduction in photocatalysis efficiency was noted after five testing cycles. Therefore, the MnO₂/BiVO₄ nanocomposite demonstrated a good potential for photocatalytic decomposition of new water contaminants.     

A novel reusable platinum nanocatalyst

Recyclability of noble metal catalysts is a challenging issue when dealing with their industrial applications. Smart pH-sensitive Pt nanoparticles were successfully prepared for the first time by using octa(N,N-diacetic acid phenylamine)silsesquioxane (OAPAS) as a macromolecular protective agent. As-prepared Pt nanoparticles can self-aggregate or redisperse by only changing the pH of the system solution. In the weak acidic or alkaline solution (pH > 4.0), the Pt nanoparticles dispersed homogenously; while in the acidic solution (pH = 2.5), they self-aggregated. The dynamic self-aggregation and redispersion processes of the Pt nanoparticles driven by pH changes were revealed by transmission electron microscopy measurements. Electrocatalytic experiments proved that the platinum nanoparticles as a recyclable catalyst showed excellent activity for the hydrogenation of aldehyde after runs of five times. Such platinum nanoparticles are thereby anticipated to have great potential functioning as “smart” catalysts for industrial applications.     

Immobilization of urease in metal–organic frameworks via biomimetic mineralization and its application in urea degradation

Enzyme immobilization has been accepted as an efficient technique for improving the stability and recyclability of enzymes. Herein, biomimetic mineralization strategy was employed to achieve the immobilization of urease in a type of metal–organic frameworks(zeolite imidazolate framework-8, ZIF-8), and the immobilized enzyme urease@ZIF-8 was systematically evaluated for its structure, activity, stability and recyclability, using the hydrolysis of urea as a model. The entrapment of urease was found to be realized in a synchronous manner with the formation of ZIF-8 crystal. The loading of urease in ZIF-8 was measured to be ca. 10.6% through the bicinchoninic acid(BCA) protein assay. The encapsulated urease could efficiently maintain its native conformation, which endowed the immobilized urease with excellent activity and stability, even in harsh conditions(e.g., in the presence of trypsin, acidic or alkali conditions, or at high temperature). Further, urease@ZIF-8 exhibited good recyclability during the degradation of urea, in which it could keep 58.86% of initial activity after being used for 5 cycles. Thus, biomimetic mineralization could be potentially utilized as a promising method to prepare immobilized ureases with superior activity, stability and recyclability, thereby facilitating the construction of efficient catalysts for industrial biocatalysis and biosensing.