S.A. Al-Sayari

Ease synthesis of mesoporous WO3-TiO2 nanocomposites with enhanced photocatalytic performance for photodegradation of herbicide imazapyr under visible light and UV illumination.

Herein, we report the ease synthesis of mesoporous WO3-TiO2 nanocomposites at different WO3 contents (0-5wt%) together with their photocatalytic performance for the degradation of the imazapyr herbicide under visible light and UV illumination. XRD and Raman spectra indicated that the highly crystalline anatase TiO2 phase and monoclinic and triclinic of WO3 were formed. The mesoporous TiO2 exhibits large pore volumes of 0.267cm(3)g-1 and high surface areas of 180m(2)g(-1) but they become reduced to 0.221cm(3)g(-1) and 113m(2)g(-1), respectively upon WO3 incorporation, with tunable mesopore diameter in the range of 5-6.5nm. TEM images show WO3-TiO2 nanocomposites are quite uniform with 10-15nm of TiO2 and 5-10nm of WO3 sizes. Under UV illumination, the overall photocatalytic efficiency of the 3% WO3-TiO2 nanocomposite is 3.5 and 6.6 times higher than that of mesoporous TiO2 and commercial UV-100 photocatalyst, respectively. The 3% WO3-TiO2 nanocomposite is considered to be the optimum photocatalyst which is able to degrade completely (100% conversion) of imazapyr herbicide along 120min with high photonic efficiency ∼8%. While under visible light illumination, the 0.5% WO3-TiO2 nanocomposite is the optimum photocatalyst which achieves 46% photocatalytic efficiency.

Sensitive and fast response ethanol chemical sensor based on as-grown Gd2O3 nanostructures

Abstract Well crystalline gadolinium oxide (Gd 2 O 3 ) nanostructures were grown by annealing the hydrothermally as-prepared nanostructures without using any template. Microscopic studies of Gd 2 O 3 nanostructures were recorded along the [111] direction due to the clearly resolved interplanar distance d (222) ∼0.31 nm of the cubic crystal structure Gd 2 O 3 . Sensing mechanism of Gd 2 O 3 as efficient electron mediator for the detection of ethanol was explored. As-fabricated sensor demonstrated the high-sensitivity of ∼0.266 μAm/M/cm 2 with low detection limit (∼52.2 μmol/L) and correlation coefficient ( r 2 , 0.618). To the best of our knowledge, this was the first report for the detection of ethanol using as-grown (at 1000 °C) Gd 2 O 3 nanostructures by simple and reliable I-V technique and rapid assessment of the reaction kinetics (in the order of seconds). The low cost of the starting reagents and the simplicity of the synthetic route made it a promising chemical sensor for the detection of various toxic analytes, which are not environmentally safe.

Renewable Syngas Production via Dry Reforming of Methane

Biogas produced by the anaerobic digestion of biomass can be exploited directly as a fuel for small-to-medium-scale combined heat and power production, or as a renewable carbon source for the production of synthesis gas and/or hydrogen for industrial syntheses or energetic purposes. Since biogas contains CH4 and CO2 as two main components, it could be processed to a syngas according to a well-reported technological process called CO2 reforming of methane (dry reforming). We highlight the dry reforming of biogas as one area of activity where catalysts are already a significant focus of worldwide research efforts. Nickel catalysts are highly active for reforming reactions, and their cost is much lower compared with noble metals, which makes them suitable for a cost-effective commercial reforming process. For this reason, Ni-based catalysts are extensively studied, with emphasis on the effect of catalyst composition, preparation method, and pre-treatment. Unfortunately, nickel is more prone to carbon deposition. Improvement in the performance of Ni-based catalysts by incorporation of a second metal to catalyst composition and use of different Ni catalyst precursors is discussed in some detail. The challenges for catalysts applied to the dry reforming of biogas (activity, sulfur poisoning, carbon formation, and sintering) are also examined in order to reveal the specific needs and responses for the reforming process. A brief account of strategies and approaches adopted in the search for catalysts that respond to the above challenges is given here.

Highly selective colorimetric detection and preconcentration of Bi(III) ions by dithizone complexes anchored onto mesoporous TiO2

We successfully developed a single-step detection and removal unit for Bi(III) ions based on dithizone (DZ) anchored on mesoporous TiO2 with rapid colorometric response and high selectivity for the first time. [(DZ)3-Bi] complex is easily separated and collected by mesoporous TiO2 as adsorbent and preconcentrator without any color change of the produced complex onto the surface of mesoporous TiO2 (TiO2-[(DZ)3-Bi]) at different Bi(III) concentrations. This is because highly potent mesoporous TiO2 architecture provides proficient channeling or movement of Bi(III) ions for efficient binding of metal ion, and the simultaneous excellent adsorbing nature of mesoporous TiO2 provides an extra plane for the removal of metal ions.

Green material: ecological importance of imperative and sensitive chemi-sensor based on Ag/Ag2O3/ZnO composite nanorods

In this report, we illustrate a simple, easy, and low-temperature growth of Ag/Ag2O3/ZnO composite nanorods with high purity and crystallinity. The composite nanorods were structurally characterized by field emission scanning electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy which confirmed that synthesized product have rod-like morphology having an average cross section of approximately 300 nm. Nanorods are made of silver, silver oxide, and zinc oxide and are optically active having absorption band at 375 nm. The composite nanorods exhibited high sensitivity (1.5823 μA.cm−2.mM−1) and lower limit of detection (0.5 μM) when applied for the recognition of phenyl hydrazine utilizing I-V technique. Thus, Ag/Ag2O3/ZnO composite nanorods can be utilized as a redox mediator for the development of highly proficient phenyl hydrazine sensor.

Electrostatically-induced trajectory switching system on a multi-inlet-multi-outlet superhydrophobic droplet guiding track

A multi-inlet-multi-outlet (MIMO) superhydrophobic droplet guiding track was demonstrated for water droplet manipulation using an electrostatic force-induced trajectory switching system. Without applying an external electrostatic field, the water droplet rolled along the superhydrophobic guiding track due to its extreme water repellent properties and gravitational force. By applying a DC bias to a capacitor above the guiding track, the trajectory of the water droplet can be easily controlled by the electrostatic attraction. Electrostatically-induced trajectory switching was successfully achieved when the electrostatic and gravitational forces exerted on the water droplet were properly balanced. On a MIMO superhydrophobic droplet guiding track with three inlets and four outlets, the water droplet was guided along the intended trajectory.

Utilization of CuO Layered Hexagonal Disks for Room‐Temperature Aqueous Ammonia Sensing Application

In this paper, CuO layered hexagonal disks based ammonium hydroxide chemical sensor has been fabricated which demonstrated good sensitivity and detection limit. The CuO layered hexagonal disks were synthesized in large quantity via facile hydrothermal process at low‐temperature of 130 °C and characterized in detail in terms of their structural and optical properties [1]. The detailed structural and optical properties of as‐synthesized CuO layered hexagonal disks confirmed the good crystallinity with monoclinic structure and good optical properties for synthesized products [1]. The fabricated ammonium hydroxide chemical sensor based on CuO layered hexagonal disks demonstrate a good sensitivity of 0.07166 μA cm−2  mM−1, detection limit = 1.333 μM, response time less than 10 s, linear dynamic range (LDR) from 5.0 μM to 5.0 mM. This study reveals that simply synthesized CuO materials can be efficiently as an electron mediator to fabricate efficient chemical sensors.

Growth of branched In‐doped ZnO nanowires: Structural and Optical Properties

Well‐crystallized branched Indium (In)‐doped ZnO nanowires were grown on silicon substrate via simple thermal evaporation process by using metallic zinc and indium powders in the presence of oxygen. The as‐grown branched nanowires were examined in terms of their morphological, structural and optical properties using field emission scanning electron microscopy (FESEM) attached with energy dispersive spectroscopy (EDS), X‐ray diffraction and room‐temperature photoluminescence (PL) spectroscopy. The morphological and structural characterizations confirmed that the as‐grown products are branched nanowires, grown in high‐density and possessing well‐crystalline structures. The room‐temperature photoluminescence (PL) spectrum exhibited a very small UV emission and a broad band in the visible region indicating the presence of structural defects due to insertion of In‐atoms in the lattices of as‐grown nanowires. The presence of a strong green emission in the room‐temperature PL spectrum demonstrates that these str...