Investigation of bandgap energies of a single phase Zn(₁₋ₓ)CuₓO nanoparticles / Suraya Ahmad Kamil … [et al.]

ZnO nanostructures are extensively studied due to their attractive characteristics and behaviour with wide band gap (3.4 eV) and large exciton binding energy (60 meV) Recently, there have been a lot of interests in studying modified ZnO nanostructures. The prospect of magnetically controlled operation of semiconductor devices has provoked intensive research to develop transition metal doped wide-band-gap semiconductors,i.e. diluted magnetic semiconductors (DMS) with room temperature ferromagnetism. Among transition metals, Cu is an especially interesting dopant because that Cu-related compounds are not strongly ferromagnetic. Transition metal-doped ZnO offers the potential for realizing room temperature operation of active spintronic devices as well as rich and fascinating fundamental physics

Catalytic supercritical water gasification of oil palm frond biomass using nanosized MgO doped Zn catalysts

In this work, nanosized MgO doped Zn catalysts (Mg1-x Znx O; x = 0.05, 0.10, 0.15, 0.20) were catalyzed the supercritical water gasification (SCWG) of oil palm frond (OPF) biomass for hydrogen production. Increased the amount of Zn in the catalyst enlarged the crystallite size, thus, reduced the surface area. Interestingly, all the synthesized catalysts have crystallite sizes of less than 50 nm. In-depth Rietveld refinement analysis revealed that the enlargement of the crystallite size is due to the phenomenon of cell expansion when the smaller Mg2+ ions being replaced by the larger Zn2+ ions during the doping process. Increased the Zn content also improved the basicity properties. Among the synthesized catalysts, the Mg0.80 Zn0.20 O exhibited the highest total gas volume of 213.5 ml g-1 of the biomass with 438.1% of increment in terms of H2 yield. The metal oxide doped materials serve as a new catalyst structure system for the SCWG technology

Structural and catalytic studies of Mg1-xNixO nanomaterials for gasification of biomass in supercritical water for H2-rich syngas production

Nowadays, catalytic supercritical water gasification (SCWG) is undoubtedly used for production of H2-rich syngas from biomass. The present study reported the synthesis and characterisation of Mg1-xNixO (x ¼ 0.05, 0.10, 0.15, 0.20) nanomaterials that were obtained via self-propagating combustion (SPC) method, and catalysed the SCWG for the first time. It had found that increased the nickel (Ni) content in the catalyst reduced the crystallite size, thus, increased the specific surface area, which influenced the catalytic activity. The specific surface area followed the order of Mg0.95Ni0.05O (36.2 m2 g1 ) < Mg0.90Ni0.10O (58.9 m2 g1 ) < Mg0.85Ni0.15O (63.6 m2 g1 ) < Mg0.80Ni0.20O (67.9 m2 g1 ). From the Rietveld refinement, the Ni that was successfully partial substituted in the cubic crystal structure of MgO resulting in a cell contraction which ascribed the reduction of crystallite size. Increased the amount of Ni also narrowed the pore size distribution ranging between 4.17 nm and 6.23 nm, as well as increased the basicity active site up to 5741.0 mmol g1 at medium basic strength. All the synthesised nanocatalysts were catalysed the SCWG of OPF (oil palm frond) biomass. Among them, the mesoporous Mg0.80Ni0.20O nanocatalyst exhibited the highest total gas volume of 193.5 mL g1 with 361.7% increment of H2 yield than that of the non-catalytic reaction

Fabrication, functionalization, and application of carbon nanotube-reinforced polymer composite: an overview

A novel class of carbon nanotube (CNT)-based nanomaterials has been surging since 1991 due to their noticeable mechanical and electrical properties, as well as their good electron transport properties. This is evidence that the development of CNT-reinforced polymer composites could contribute in expanding many areas of use, from energy-related devices to structural components. As a promising material with a wide range of applications, their poor solubility in aqueous and organic solvents has hindered the utilizations of CNTs. The current state of research in CNTs—both single-wall carbon nanotubes (SWCNT) and multiwalled carbon nanotube (MWCNT)-reinforced polymer composites—was reviewed in the context of the presently employed covalent and non-covalent functionalization. As such, this overview intends to provide a critical assessment of a surging class of composite materials and unveil the successful development associated with CNT-incorporated polymer composites. The mechanisms related to the mechanical, thermal, and electrical performance of CNT-reinforced polymer composites is also discussed. It is vital to understand how the addition of CNTs in a polymer composite alters the microstructure at the micro- and nano-scale, as well as how these modifications influence overall structural behavior, not only in its as fabricated form but also its functionalization techniques. The technological superiority gained with CNT addition to polymer composites may be advantageous, but scientific values are here to be critically explored for reliable, sustainable, and structural reliability in different industrial needs

Effects of Cationic Surfactant in Sol-gel Synthesis of Nano Sized Magnesium Oxide

AbstractIn this study, sol-gel method was used to synthesize nano sized of magnesium oxide (MgO). Magnesium acetate tetrahydrate and tartaric acid have been dissolved in ethanol and formed a precursor before calcined at 600 ¡C for 6h to produce MgO nanoparticles. A cationic surfactant (cetyltrimethylammonium bromide, CTAB) had used in the sol-gel reaction to reduce agglomeration of the nanoparticles. Two samples (MgO and MgO-CTAB) were characterized using simultaneous thermogravimetric analyzer (STA), X-ray diffractometer (XRD), field emission scanning electron microscope (FESEM) and nitrogen adsorption-desorption measurement. Formation of the samples via a sol-gel route is discussed and confirmed using the STA results. The precursor formed was identified as magnesium tartrate and decomposed to MgO and MgO-CTAB after the calcinations, and gave a single phase of samples as shown by the XRD patterns. The used of CTAB in this sol-gel method gives the MgO nanoparticles with less agglomeration. This was proved by the FESEM micrographs, the MgO-CTAB has spherical shape and the agglomeration seems to be less than the MgO. It suggests that the cationic surfactant controls the morphology of the samples

Mechanism of the formation of novel Al2-xHfxO3 materials via a combustion synthesis method

In this paper, the synthesis mechanism of novel hafnium-doped alumina, Al2-xHfxO3 (x ?= ?0.001, 0.002 and 0.003) materials have been successfully formed via a self-propagating combustion (SPC) method. In-depth study of the materials through characterization by simultaneous thermogravimetric analysis (STA), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and energy dispersive X-ray (EDX) were systematically done. STA technique were used to characterize the thermal profile of the precursors. From the analysis, the synthesis mechanism of the materials was proposed. XRD results reveal that hafnium doped materials correspond to the hexagonal crystal structure of Al2O3 that shows a success of the substitutional doping. The FESEM micrographs shown that the morphology of the materials was not significantly affected by the dopant concentrations. However, the presence of Hf4+ ions in Al2O3 were confirmed where the synthesized stoichiometry of all materials were perfectly identical to the obtained stoichiometry from EDX

Fabrication, functionalization, and application of carbon nanotube-reinforced polymer composite: An overview

A novel class of carbon nanotube (CNT)-based nanomaterials has been surging since 1991 due to their noticeable mechanical and electrical properties, as well as their good electron transport properties. This is evidence that the development of CNT-reinforced polymer composites could contribute in expanding many areas of use, from energy-related devices to structural components. As a promising material with a wide range of applications, their poor solubility in aqueous and organic solvents has hindered the utilizations of CNTs. The current state of research in CNTs-both singlewall carbon nanotubes (SWCNT) and multiwalled carbon nanotube (MWCNT)-reinforced polymer composites-was reviewed in the context of the presently employed covalent and non-covalent functionalization. As such, this overview intends to provide a critical assessment of a surging class of composite materials and unveil the successful development associated with CNT-incorporated polymer composites. The mechanisms related to the mechanical, thermal, and electrical performance of CNT-reinforced polymer composites is also discussed. It is vital to understand how the addition of CNTs in a polymer composite alters the microstructure at the micro- and nano-scale, as well as how these modifications influence overall structural behavior, not only in its as fabricated form but also its functionalization techniques. The technological superiority gained with CNT addition to polymer composites may be advantageous, but scientific values are here to be critically explored for reliable, sustainable, and structural reliability in different industrial needs