Room Temperature Synthesis of Nanostructured ZnO: Active Visible Photocatalyst in the Degradation of Methylene Blue

Nanostructured ZnO was prepared using a facile solution-phase method at room temperature without need to calcination. Oxidation of zinc sulfate by sodium hypochlorite in the presence of polyethylene glycol (PEG) and sodium hydroxide (NaOH) gave pure nanostructured zinc oxide (ZnO-NPs). The structure and physicochemical properties of the material were determined by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (IR), Energy Dispersive X-ray Spectroscopy (EDS), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), UV–Vis diffuse reflectance and their optical Properties. ZnO particles were successfully distributed in two-dimensional sheet with a nanometric thickness and a random distribution. The activity was evaluated for photocatalytic degradation of methylene blue (MB) by a study of experimental conditions such as the effect of the mass of the catalyst, the effect of the initial concentration of the dye and the effect of the volume of the oxidizing agent. The kinetics of the reaction follow a pseudo-first order.

A Facile and Flexible Approach for Large-Scale Fabrication of ZnO Nanowire Film and Its Photocatalytic Applications

A novel strategy for large-scale synthesis of ZnO nanowire film is reported, which inherits the advantages of the solution-phase method and seeded growth process, such as low-temperature, efficient, economical, facile and flexible. It is easy to implement on various metals through room-temperature electrodeposition, followed by hydrothermal treatment at 90 °C, and suitable for industrialized production. The ZnO nanowires with an average wire diameter about 40 nm are in situ grown from and on nanocrystalline zinc coating, which forms a strong metallurgical bonding with the substrates. The p-type ZnO nanowire film has a well-preferred orientation along the (100) direction and a wurtzite structure, thereby displaying an effective photocatalytic capability for carcinogenic Cr6+ ions and CO2 greenhouse gas reduction under visible light irradiation. In addition to these features, the ZnO nanowire film is easy to recycle and, therefore, it has broad application prospects in contaminant degradation and renewable energy.

Anion Distribution, Structural Distortion, and Symmetry-Driven Optical Band Gap Bowing of Mixed Halide Cs2SnX6 Vacancy Ordered Double Perovskites

Mixed anion compounds in the Fm-3m vacancy ordered perovskite structure were synthesised and characterised experimentally and computationally with a focus on compounds where A = Cs+. Pure anion Cs₂SnX₆ compounds were formed with X = Cl, Br and I using a room temperature solution phase method. Mixed anion compounds were formed as solid solutions of Cs₂SnCl₆ and Cs₂SnBr₆ and a second series from Cs₂SnBr₆ and Cs₂SnI₆. Single phase structures formed across the entirety of both composition series, with no evidence of long range anion ordering observed by diffraction. A distortion of the cubic A2BX6 structure was identified in which the spacing of the BX6 octahedra changes to accommodate the A site cation without reduction of overall symmetry. Optical band gap values varied with anion composition between 4.89 eV in Cs₂SnCl₆to 1.35 eV in Cs₂SnI₆, but proved highly non-linear with changes in composition. In mixed halide compounds it was found that lower energy optical transitions appeared that were not present in the pure halide compounds, and this could be attributed to lowering of the local symmetry within the tin halide octahedra. The electronic structure was characterised by photoemission spectroscopy, and Raman spectroscopy revealed vibrational modes in the mixed halide compounds that could be assigned to particular mixed halide octahedra. This analysis was used to determine the distribution of octahedra types in mixed anion compounds, which was found to be consistent with a near-random distribution of halide anions throughout the structure, although some deviations from random halide distribution were noted in mixed iodide-bromide compounds, where the larger iodide anions preferentially adopted trans configurations.

Anion Distribution, Structural Distortion, and Symmetry-Driven Optical Band Gap Bowing of Mixed Halide Cs2SnX6 Vacancy Ordered Double Perovskites

Mixed anion compounds in the Fm-3m vacancy ordered perovskite structure were synthesised and characterised experimentally and computationally with a focus on compounds where A = Cs+. Pure anion Cs₂SnX₆ compounds were formed with X = Cl, Br and I using a room temperature solution phase method. Mixed anion compounds were formed as solid solutions of Cs₂SnCl₆ and Cs₂SnBr₆ and a second series from Cs₂SnBr₆ and Cs₂SnI₆. Single phase structures formed across the entirety of both composition series, with no evidence of long range anion ordering observed by diffraction. A distortion of the cubic A2BX6 structure was identified in which the spacing of the BX6 octahedra changes to accommodate the A site cation without reduction of overall symmetry. Optical band gap values varied with anion composition between 4.89 eV in Cs₂SnCl₆to 1.35 eV in Cs₂SnI₆, but proved highly non-linear with changes in composition. In mixed halide compounds it was found that lower energy optical transitions appeared that were not present in the pure halide compounds, and this could be attributed to lowering of the local symmetry within the tin halide octahedra. The electronic structure was characterised by photoemission spectroscopy, and Raman spectroscopy revealed vibrational modes in the mixed halide compounds that could be assigned to particular mixed halide octahedra. This analysis was used to determine the distribution of octahedra types in mixed anion compounds, which was found to be consistent with a near-random distribution of halide anions throughout the structure, although some deviations from random halide distribution were noted in mixed iodide-bromide compounds, where the larger iodide anions preferentially adopted trans configurations.

Ambient fast, large-scale synthesis of entropy-stabilized metal–organic framework nanosheets for electrocatalytic oxygen evolution

A high entropy metal–organic framework (HE-MOF) with five near-equimolar components was synthesized by a solution phase method and served as an electrochemical oxygen evolution catalyst.

Metal-free C 60 /CNTs/g-C 3 N 4 ternary heterostructures: synthesis and enhanced visible-light-driven photocatalytic performance

A metal-free C 60 /CNTs/g-C 3 N 4 nanoheterostructure with excellent visible-light photocatalysis for rhodamine B (Rh B) degradation has been reported. Via a convenient low-temperature solution-phase method, g-C 3 N 4 nanosheets can serve as substrate for dispersion of C 60 /CNTs. The loading of C 60 /CNTs onto g-C 3 N 4 nanosheets surfaces significantly enhanced visible-light-driven photocatalytic activity of g-C 3 N 4 catalyst, for oxidation of organic pollutant (Rh B, 100%). Excellent photocatalytic properties of C 60 /CNTs/g-C 3 N 4 can be predominantly attributed to the intimate interfacial contact among constructing compounds, increased specific surface area and enhanced light adsorption efficiency resulted from C 60 /CNTs carbon materials. Particularly, the synergistic heterostructure interaction remarkably hinders the electron–hole pairs recombination, giving rise to significantly enhanced photocatalytic performance of C 60 /CNTs/g-C 3 N 4 in comparison with other counterparts.

Ferromagnetic Cr2Te3 nanorods with ultrahigh coercivity

Ferromagnetic Cr2Te3 nanorods with ultrahigh coercivity were synthesized by a one-pot high-temperature organic-solution-phase method.

Flexible double-cross-linked cellulose-based hydrogel and aerogel membrane for supercapacitor separator

A cellulose-based flexible double-cross-linked hydrogel with hierarchical porosity (max. 80%) was obtained by a facile solution-phase method by using polydopamine (PDA) as a crosslinker between cellulose and polyacrylamide (PAM).