Ahmed A. Ibrahim

Growth and properties of Ag-doped ZnO nanoflowers for highly sensitive phenyl hydrazine chemical sensor application

We report here the fabrication of a robust, highly sensitive, reliable and reproducible phenyl hydrazine chemical sensor using Ag-doped ZnO nanoflowers as efficient electron mediators. The Ag-doped ZnO nanoflowers were synthesized by facile hydrothermal process at low-temperature and characterized in detail in terms of their morphological, structural, compositional and optical properties. The detailed morphological and structural characterizations revealed that the synthesized nanostructures were flower-shaped, grown in very high-density, and possessed well-crystalline structure. The chemical composition confirmed the presence of Ag into the lattices of Ag-doped ZnO nanoflowers. High sensitivity of ≈ 557.108 ± 0.012 mAcm(-2)(mol L(-1))(-1) and detection limit of ≈ 5 × 10(-9) mol L(-1) with correlation coefficient (R) of 0.97712 and short response time (10.0 s) were observed for the fabricated chemical sensor towards the detection of phenyl hydrazine by using a simple current-voltage (I-V) technique. Due to high sensitivity and low-detection limit, it can be concluded that Ag-doped ZnO nanoflowers could be an effective candidate for the fabrication of phenyl hydrazine chemical sensors.

Two-dimensional ytterbium oxide nanodisks based biosensor for selective detection of urea

Herein, we demonstrate synthesis and application of two-dimensional (2D) rectangular ytterbium oxide (Yb2O3) nanodisks via a facile hydrothermal method. The structural, morphological, compositional, crystallinity, and phase properties of as-synthesized nanodisks were carried out using several analytical techniques that showed well defined 2D rectangular nanodisks/sheet like morphologies. The average thickness and edge length of the nanosheet structures were 20 ± 5nm and 600 ± 50nm, respectively. To develop urea biosensor, glassy carbon electrodes (GCE) were modified with Yb2O3 nanodisks, followed by urease immobilization and Nafion membrane covering (GCE/Yb2O3/Urease/Nafion). The fabricated biosensor showed sensitivity of 124.84μAmM-1cm-2, wide linear range of 0.05-19mM, detection limit down to ~ 2μM, and fast response time of ~ 3s. The developed biosensor was also used for the urea detection in water samples through spike-recovery experiments, which illustrates satisfactory recoveries. In addition, the obtained desirable selectivity towards specific interfering species, long-term stability, reproducibility, and repeatability further confirm the potency of as-fabricated urea biosensor.

Fabrication and Characterization of Highly Sensitive Acetone Chemical Sensor Based on ZnO Nanoballs

Highly sensitive acetone chemical sensor was fabricated using ZnO nanoballs modified silver electrode. A low temperature, facile, template-free hydrothermal technique was adopted to synthesize the ZnO nanoballs with an average diameter of 80 ± 10 nm. The XRD and UV-Vis. studies confirmed the excellent crystallinity and optical properties of the synthesized ZnO nanoballs. The electrochemical sensing performance of the ZnO nanoballs modified AgE towards the detection of acetone was executed by simple current–voltage (I–V) characteristics. The sensitivity value of ∼472.33 μA·mM−1·cm−2 and linear dynamic range (LDR) of 0.5 mM–3.0 mM with a correlation coefficient (R2) of 0.97064 were obtained from the calibration graph. Experimental limit of detection (LOD) for ZnO nanoballs modified AgE was found to be 0.5 mM.

A Highly-Sensitive Picric Acid Chemical Sensor Based on ZnO Nanopeanuts

Herein, we report a facile synthesis, characterization, and electrochemical sensing application of ZnO nanopeanuts synthesized by a simple aqueous solution process and characterized by various techniques in order to confirm the compositional, morphological, structural, crystalline phase, and optical properties of the synthesized material. The detailed characterizations revealed that the synthesized material possesses a peanut-shaped morphology, dense growth, and a wurtzite hexagonal phase along with good crystal and optical properties. Further, to ascertain the useful properties of the synthesized ZnO nanopeanut as an excellent electron mediator, electrochemical sensors were fabricated based on the form of a screen printed electrode (SPE). Electrochemical and current-voltage characteristics were studied for the determination of picric acid sensing characteristics. The electrochemical sensor fabricated based on the SPE technique exhibited a reproducible and reliable sensitivity of ~1.2 μA/mM (9.23 μA·mM−1·cm−2), a lower limit of detection at 7.8 µM, a regression coefficient (R2) of 0.94, and good linearity over the 0.0078 mM to 10.0 mM concentration range. In addition, the sensor response was also tested using simple I-V techniques, wherein a sensitivity of 493.64 μA·mM−1·cm−2, an experimental Limit of detection (LOD) of 0.125 mM, and a linear dynamic range (LDR) of 1.0 mM–5.0 mM were observed for the fabricated picric acid sensor.

Highly sensitive and selective non-enzymatic monosaccharide and disaccharide sugar sensing based on carbon paste electrodes modified with perforated NiO nanosheets

Herein, we report the fabrication and detailed characterization of a new electrochemical enzyme-free sensor for the direct sensing of monosaccharide and disaccharide sugars based on perforated NiO nanosheets (NSs). The NiO nanosheets were synthesized by a facile hydrothermal process followed by annealing and they were characterized in terms of their morphological, structural, compositional and optical properties. Detailed characterization confirmed the large-scale synthesis, good crystallinity and high purity of the synthesized perforated NiO nanosheets. To fabricate sugar sensors, sensor electrodes were prepared by modifying carbon paste with the perforated NiO nanosheets. Cyclic voltammetry and amperometry techniques were used to investigate the effect of the NiO nanosheets on the electrocatalytic oxidation of monosaccharide and disaccharide sugars. The electrodes exhibit a high sensitivity to glucose (724 μA mM−1 cm−2), with a low detection limit (10 μM), and respond over a wide linear range (from 50 μM to 3 mM). The analytical performance of the developed sensors, in addition to their ease of fabrication, qualifies them to be a good platform for enzyme-free sugar sensing.

In-Doped ZnO Hexagonal Stepped Nanorods and Nanodisks as Potential Scaffold for Highly-Sensitive Phenyl Hydrazine Chemical Sensors

Herein, we report the growth of In-doped ZnO (IZO) nanomaterials, i.e., stepped hexagonal nanorods and nanodisks by the thermal evaporation process using metallic zinc and indium powders in the presence of oxygen. The as-grown IZO nanomaterials were investigated by several techniques in order to examine their morphological, structural, compositional and optical properties. The detailed investigations confirmed that the grown nanomaterials, i.e., nanorods and nanodisks possess well-crystallinity with wurtzite hexagonal phase and grown in high density. The room-temperature PL spectra exhibited a suppressed UV emissions with strong green emissions for both In-doped ZnO nanomaterials, i.e., nanorods and nanodisks. From an application point of view, the grown IZO nanomaterials were used as a potential scaffold to fabricate sensitive phenyl hydrazine chemical sensors based on the I–V technique. The observed sensitivities of the fabricated sensors based on IZO nanorods and nanodisks were 70.43 μA·mM−1·cm−2 and 130.18 μA·mM−1·cm−2, respectively. For both the fabricated sensors, the experimental detection limit was 0.5 μM, while the linear range was 0.5 μM–5.0 mM. The observed results revealed that the simply grown IZO nanomaterials could efficiently be used to fabricate highly sensitive chemical sensors.

Fabrication and Characterization of Dye-Sensitized Solar Cells Based on Flower Shaped ZnO Nanostructures

Herein, we report a facile synthesis, characterization and dye sensitized solar cell (DSSC) application of flower-shaped ZnO nanostructures. The flower-shaped ZnO nanostructures were synthesized by low-temperature hydrothermal process and characterized in detail by several techniques. The detailed morphological studies confirmed that the flower-shaped structures are formed by the accumulation of several nanoneedles which are axially arranged through their bases in a special fashion that they made flower-like morphologies. The compositional, structural and optical characterizations revealed that the synthesized flowers possess high purity, well-crystallinity with the wurtzite hexagonal phase and good optical properties. The synthesized flower-shaped ZnO nanostructures were used as photoanode to fabricate DSSC which attained a reasonable solar to electrical conversion efficiency of ~1.1%, open-circuit current (VOC) of 0.611 V, short circuit current (JSC) of 3.53 mA/cm2 and fill factor (FF) of 0.51.