Facile combustion synthesis of Ag2O nanoparticles using cantaloupe seeds and their multidisciplinary applications

Silver oxide nanoparticles (Ag₂O NPs) were prepared using cantaloupe (Cucumis melo) seeds as a fuel by employing a green synthesis method. The prepared Ag₂O NPs were investigated using powder X-ray diffraction (PXRD), UV–visible spectrum, Fourier transform infrared analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM) with energy-dispersive spectroscopy, and photoluminescence studies. PXRD data reveal the establishment of cubic crystal structure of Ag₂O NPs. According to SEM and TEM results, the morphology of the prepared NPs was agglomerated and spherical. The photodegradation activity of the prepared Ag₂O NPs over methylene blue dye was promising under visible light irradiation. Furthermore, the antimicrobial assay of the synthesized Ag₂O NPs was carried out by the disc diffusion method against Gram-positive and Gram-negative microbial strains.     

Recyclable alkylated Ru(bpy)32+ complex as a visible-light photoredox catalyst for perfluoroalkylation

A recyclable Ruthenium tris [4,4′-bis (dinonylmethyl)-2,2′-bipyridine] (Ru[(DNM)₂bpy]₃²⁺) photocatalyst (PC) was synthesized. Hexane-phase-selective solubility allowed its simple and efficient separation from reaction products via solvent extraction. The excellent catalytic activity and recoverability were demonstrated in batch and flow perfluoroalkylation reactions of coumarin under visible-light irradiation. High reaction rates and easy reusability of the catalyst make this approach attractive for large-scale applications.     

Synthesis and polypyrrole-loading study of antifungal medicine fluconazole functionalized Keggin polyoxotungstates

To rich the coordination polymer and polyoxometalate (POM) chemistry, two new hybrid compounds based on Keggin POMs with antifungal medicine fluconazole (Hfkz = [1-(2,4-difluorophenyl)-1,1-bis [(1H-1,2,4-triazol-1-yl)-methyl]methanol]), [Ag₄(Hfkz)₂][PW₁₂O₄₀] (AgFkzPW₁₂) and [Ag₄(Hfkz)₂][SiW₁₂O₄₀] (AgFkzSiW₁₂), have been successfully synthesized and structurally characterized. Moreover, to improve the photogenerated electron-hole pair separation properties, the surface of hybrid compounds was loaded by polypyrrole (PPy) through a chemical oxidation polymerization process in situ fabricating hybrid nanocomposites AgFkzPW₁₂@PPy and AgFkzSiW₁₂@PPy. As a result, the Hfkz molecules were successfully grafted onto the surface of the Keggin polyoxoanions, and their nanocomposites exhibit better photocatalytic activity than the respective matrix compounds under the irradiation of visible light.     

硫比例对Zn0.8Cd0.2S-En杂化固溶体光催化制氢性能的影响

采用溶剂热制备了具有不同厚度和大小的Zn0.8Cd0.2S-乙二胺杂化纳米片固溶体,系统地考察了制备过程中S/(Zn+Cd)摩尔比对所制备的光催化材料的组成与结构、光电性质以及亲水性能的影响。HR-TEM照片表明,随着制备体系中硫脲含量的增加,固溶体纳米片表面逐渐平整;荧光发射光谱结果表明,合适的S/(Zn+ Cd)摩尔比可以提高光催化材料光生电子和空穴的分离效率;光催化性能评价表明,制备过程中的S/(Zn+ Cd)原子比对其制氢活性有明显影响,在可见光照射下,S/(Zn+Cd)为4.75时,合成的Zn0.8Cd0.2S-En样品表现出最高的氢气产率,其可达到12100 μmol·h-1·g-1,分别是S/(Zn+Cd)为1.2和6.5时合成的Zn0.8Cd0.2S-En样品产氢量的2.2倍和1.7倍。光催化活性的提高与样品较少的表面缺陷、合适的形貌以及高光生电子和空穴分离效率有关。     

A Methylthio‐Functionalized‐MOF Photocatalyst with High Performance for Visible‐Light‐Driven H2 Evolution

Recently, the emergence of photoactive metal–organic frameworks (MOFs) has given great prospects for their applications as photocatalytic materials in visible‐light‐driven hydrogen evolution. Herein, a highly photoactive visible‐light‐driven material for H₂ evolution was prepared by introducing methylthio terephthalate into a MOF lattice via solvent‐assisted ligand‐exchange method. Accordingly, a first methylthio‐functionalized porous MOF decorated with Pt co‐catalyst for efficient photocatalytic H₂ evolution was achieved, which exhibited a high quantum yield (8.90 %) at 420 nm by use sacrificial triethanolamine. This hybrid material exhibited perfect H₂ production rate as high as 3814.0 μmol g^?1 h^?1, which even is one order of magnitude higher than that of the state‐of‐the‐art Pt/MOF photocatalyst derived from aminoterephthalate.     

Relationship between the component synthesis order of zinc ferrite–titania nanocomposites and their performances as visible light-driven photocatalysts for relevant organic pollutant degradation

The main objective of this work was to investigate the influence of the order of component synthesis of zinc ferrite–titania nanocomposites on their structural, morphologic, textural, light absorption properties, and performances as photocatalysts. In this respect, nanocomposite materials with 10ZnFe₂O₄90TiO₂ (wt %) composition were prepared via a two-step synthesis procedure by alternating the order of the component addition during the preparation protocol and characterized by X-ray diffraction, transmission electron microscopy, energy dispersive X-ray, small-angle X-ray scattering, nitrogen sorption, and UV–vis diffuse reflectance spectroscopy. The photocatalytic activity of nanocomposites was evaluated on Rhodamine 6G degradation under visible light illumination. The photocatalytic performances of nanocomposites were clearly superior to the classical TiO₂. Nevertheless, preparing titania in the presence of a presynthesized zinc ferrite led to superior characteristics in terms of band gap value, specific surface area, and grain sizes crucial for the enhancement of the photocatalytic performances.     

Tunable Water‐Soluble Supramolecular Polymers by Visible‐Light‐Regulated Host–Guest Interactions

The development of artificial self‐assembling systems with dynamic photo‐regulation features in aqueous solutions has drawn great attention owing to the potential applications in fabricating elaborate biological materials. Here we demonstrate the fabrication of water‐soluble cucurbit[8]uril (CB[8])‐mediated supramolecular polymers by connecting the fluorinated azobenzene (FAB) containing monomers through host‐enhanced heteroternary π–π stacking interactions. Benefiting from the unique visible‐light‐induced E→Z photoisomerization of the FAB photochromophores, the encapsulation behaviors between the CB[8] macrocycle and the monomers could be regulated upon visible light irradiation, resulting in the depolymerization of such CB[8]‐mediated supramolecular polymers.     

Microstructure and Photocatalytic Property of SiO<Subscript>2</Subscript>-TiO<Subscript>2</Subscript> Under Various Process Condition

Nanophase silica-titania particles were prepared by two different synthetic routes, namely, sol–gel and hydrothermal processing. The crystallinity and crystallographic phases, particle size and surface area of the materials were controlled by varying the calcination temperature, and/or the ratio of Si to Ti. It was determined by XRD that the crystallite sizes of SiO₂-TiO₂ prepared by sol–gel and hydrothermal processing decreased from 11 to 6 nm and 12 to 9 nm, respectively, as the mole fraction of silica was increased from 0.1 to 0.4. It is proposed that the presence of the amorphous silica suppresses the growth of anatase TiO₂ grains and their phase transformation to rutile. The photocatalytic decomposition rate of 1,4-dichlorobenzene (DCB) in aqueous solution with the sol–gel derived SiO₂-TiO₂ powder prepared at 750 °C was about 10 ± 5% higher than that observed with Degussa P25, whereas the SiO₂-TiO₂ samples prepared by hydrothermal processing at 250 °C showed a slightly lower decomposition rate than P25.     

Photocatalyst Materials for Water Splitting

Various photocatalyst materials developed by the group of the present author are described. Alkali and alkaline earth tantalates have arisen as a new group of photocatalyst materials for splitting of water into H₂ and O₂ under ultraviolet irradiation. They showed activities even without co-catalysts such as Pt, being different from titanate photocatalysts. When NiO co-catalysts were loaded on the tantalate photocatalysts, the photocatalytic activities were markedly increased. Among the tantalates, NiO/NaTaO₃ doped with La showed the highest activity. BiVO₄, AgNO₃, and TiO₂ co-doped with Cr and Sb photocatalysts showed high activities for O₂ evolution in the presence of a sacrificial reagent (Ag⁺) under visible light irradiation ( > 420 nm). Pt/SrTiO₃ co-doped with Cr and Sb or Ta, Pt/NaInS₂, and Pt/AgInZn₇S₉ photocatalysts showed high activities for H₂ evolution from aqueous solutions containing reducing reagents under visible light irradiation. Furthermore, Cu- or Ni-doped ZnS photocatalysts showed H₂ evolution activities even without co-catalysts such as Pt.     

Electrochemical approach to evaluate the mechanism of photocatalytic water splitting on oxide photocatalysts

Photoelectrochemical measurements of TiO₂, NaTaO₃, and Cr or Sb doped TiO₂ and SrTiO₃ photocatalysts were carried out in H₂ and O₂ saturated electrolytes in order to evaluate the reverse reactions during water photolysis. The poor activity of TiO₂ as a result of reverse photoreactions of O₂ reduction and H₂ oxidation was revealed with the respective high cathodic and anodic photocurrents. The rise in the photocurrents at NaTaO₃ after La doping was in harmony with the doping-induced increase in the photocatalytic activity. NiO loading suppresses the O₂ photoreverse reactions, which declines photocatalytic activity, and/or promotes the photo-oxidation of water, because the O₂ photo-reduction current was scarcely observed near the flatband potential. Photocurrents of O₂ reduction and H₂ oxidation were observed under visible light for the Cr and Sb doped SrTiO₃ and TiO₂, respectively. These phenomena are in harmony with the previous reports on the photocatalysts examined with sacrificial reagents.