Template Assisted Microwave Synthesis of rGO-ZrO₂ Composites: Efficient Photocatalysts Under Visible Light

In this research, cetyltetraethyl ammonium bromide template assisted microwave procedure was utilized to synthesize reduced graphene oxide-zirconia (rGO-ZrO₂) nanocomposites by varying the rGO composition (1, 2, 5 and 10 wt%). The physico-chemical characteristics of the nanocomposites were studied using X-ray diffraction (XRD), Raman, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), diffusive reflectance ultraviolet-visible (DRUV-vis), X-ray photoelectron spectroscopy (XPS) and N2-physisorption techniques. The results from XRD, Raman and DSC studies indicate that the increase in rGO concentration resulted in the delay in ZrO₂ crystallization temperature and alteration of ZrO₂ phase from monoclinic to tetragonal due to an effective incorporation of rGO nanosheets in ZrO₂ structure. The rGO loading also have an influence in the morphology of nanocomposites, as sample with 10 wt% rGO possessed unique monolith like morphology with macro pores. All the nanocomposites were utilized as photocatalysts for degradation of crystal violet dye in visible light irradiation. The rGO-ZrO₂ nanocomposites showed high reaction rates; the nanocomposite with 5 wt% rGO showed the superior photocatalytic performance as this sample possessed low band gap energy, high surface area, pore volume and presence of surface rGO-ZrO₂ interactive species as well as the reactive -OH groups. In addition, the synthesized nanocomposites exhibited excellent recyclability for photocatalytic degradation.

Chemical Vapor Deposition Synthesis and Optical Properties of Nb2O5 Thin Films with Hybrid Functional Theoretical Insight into the Band Structure and Band Gaps

Nb₂O₅ is an important material able to exist in many polymorphs with unique optical properties and morphologies that are dependent on the synthetic route. Here we report a novel ambient-pressure chemical vapor deposition route to Nb₂O₅ via aerosol-assisted chemical vapor deposition. The amorphous as-deposited films were annealed in air to obtain the the three most stable crystal structures: orthorhombic, tetragonal, and monoclinic. The films were thoroughly characterized for their material properties, and an in-depth study into the optical properties was carried out using state-of-the-art hybrid functional theory that allowed more insight into the optical properties of the materials.

A single-source precursor approach to solution processed indium arsenide thin films

This paper reports the synthesis of the novel single-source precursor, [{(MeInAs ^t Bu)₃}₂(Me₂InAs( ^t Bu)H)₂] and the subsequent first report of aerosol-assisted chemical vapour deposition of InAs thin films. Owing to the use of the single-source precursor, highly crystalline and stoichiometric films were grown at a relatively low deposition temperature of 450 °C. Core level XPS depth profiling studies showed some partial oxidation of the film surface, however this was self-limiting and disappeared on etch profiles. Valence band XPS analysis matched well with the simulated density of state spectrum. Hall effect measurements performed on the films showed that the films were n-type with promising resistivity (3.6 × 10^-3 Ω cm) and carrier mobility (410 cm² V^-1 s^-1) values despite growth on amorphous glass substrates.

Simple and efficient protocol for synthesis of pyrido[1,2-a]pyrimidin-4-one derivatives over solid heteropolyacid catalysts

Aluminium exchnaged tungstophosphoric acid salts with Keggin structure (Al_xH_3−xPW₁₂O₄₀) were prepared and used as catalysts to synthesize pyrido[1,2-a]pyrimidines under mild reaction conditions.

Influence of crystal structure of nanosized ZrO2 on photocatalytic degradation of methyl orange

Nanosized ZrO2 powders with near pure monoclinic, tetragonal, and cubic structures synthesized by various methods were used as catalysts for photocatalytic degradation of methyl orange. The structural and textural properties of the samples were analyzed by X-ray diffraction, Raman spectroscopy, TEM, UV-vis, X-ray photoelectron spectroscopy (XPS), and N2 adsorption measurements. The performance of synthesized ZrO2 nanoparticles in the photocatalytic degradation of methyl orange under UV light irradiation was evaluated. The photocatalytic activity of the pure monoclinic ZrO2 sample is higher than that of the tetragonal and cubic ZrO2 samples under optimum identical conditions. The characterization results revealed that monoclinic ZrO2 nanoparticles possessed high crystallinity and mesopores with diameter of 100 Å. The higher activity of the monoclinic ZrO2 sample for the photocatalytic degradation of methyl orange can be attributed to the combining effects of factors including the presence of small amount of oxygen-deficient zirconium oxide phase, high crystallinity, large pores, and high density of surface hydroxyl groups.

Correction: Self-decoration of Pt metal particles on TiO2 nanotubes used for highly efficient photocatalytic H2 production

Correction for ‘Self-decoration of Pt metal particles on TiO₂ nanotubes used for highly efficient photocatalytic H₂ production’ by Sulaiman N. Basahel et al., Chem. Commun., 2014, 50, 6123–6125.

Effect of pretreatment temperature on the photocatalytic activity of microwave irradiated porous nanocrystalline ZnO

ZnO treated at 200 °C offered high photocatalytic degradation of methyl orange (99%) in a short time (90 min). The activity can be attributed to several factors including low crystallite size, high band gap energy and porosity.

Nanostructured Mg-Al hydrotalcite as catalyst for fine chemical synthesis

This paper reviews the recent research of nanostructured Mg-Al hydrotalcite (Mg-Al HT) and its application as an efficient solid base catalyst for the synthesis of fine chemicals. Mg-Al HT has many beneficial features, such as low cost, selectivity, catalytic properties, and wide range of preparation and modification methods. They hold promise for providing sought-after, environmentally friendly technologies for the 21st century. Replacement of currently used homogeneous alkaline bases for the synthesis of fine chemicals by a solid catalyst can result in catalyst re-use and waste stream reduction. We introduce briefly the structure, properties and characterization of the nanostructured Mg-Al HT. The efficacy and benign applications of Mg-Al HT as an alternative solid base to homogenous catalysts in the synthesis of fine chemicals are then reviewed. The challenges for the future applications of Mg-Al HT in the synthesis of fine chemicals in terms of green protocol processes are discussed.

Self-decoration of Pt metal particles on TiO2 nanotubes used for highly efficient photocatalytic H2 production

Pt decorated TiO₂ has, over the past decades, been a key material for photocatalytic hydrogen production.

Combinatorial atmospheric pressure chemical vapor deposition of graded TiO₂-VO₂ mixed-phase composites and their dual functional property as self-cleaning and photochromic window coatings

A combinatorial film with a phase gradient from V:TiO₂ (V: Ti ≥ 0.08), through a range of TiO₂-VO₂ composites, to a vanadium-rich composite (V: Ti = 1.81) was grown by combinatorial atmospheric pressure chemical vapor deposition (cAPCVD). The film was grown from the reaction of TiCl₄, VCl₄, ethyl acetate (EtAc), and H₂O at 550 °C on glass. The gradient in gas mixtures across the reactor induced compositional film growth, producing a single film with numerous phases and compositions at different positions. Seventeen unique positions distributed evenly along a central horizontal strip were investigated. The physical properties were characterized by wavelength dispersive X-ray (WDX) analysis, X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and UV-visible spectroscopy. The functional properties examined included the degree of photoinduced hydrophilicity (PIH), UVC-photocatalysis, and thermochromism. Superhydrophilic contact angles could be achieved at all positions, even within a highly VO₂-rich composite (V: Ti = 1.81). A maximum level of UVC photocatalysis was observed at a position bordering the solubility limit of V:TiO₂ (V: Ti ≈ 0.21) and fragmentation into a mixed-phase composite. Within the mixed-phase TiO₂: VO₂ composition region (V: Ti = 1.09 to 1.81) a decrease in the semiconductor-to-metal transition temperature of VO₂ from 68 to 51 °C was observed.