Synthesis of benzylidenemalononitrile by Knoevenagel condensation through monodisperse carbon nanotube-based NiCu nanohybrids.

Monodisperse nickel/copper nanohybrids (NiCu@MWCNT) based on multi-walled carbon nanotubes (MWCNT) were prepared for the Knoevenagel condensation of aryl and aliphatic aldehydes. The synthesis of these nanohybrids was carried out by the ultrasonic hydroxide assisted reduction method. NiCu@MWCNT nanohybrids were characterized by analytical techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), and Raman spectroscopy. According to characterization results, NiCu@MWCNT showed that these nanohybrids form highly uniform, crystalline, monodisperse, colloidally stable NiCu@MWCNT nanohybrids were successfully synthesized. Thereafter, a model reaction was carried out to obtain benzylidenemalononitrile derivatives using NiCu@MWCNT as a catalyst, and showed high catalytic performance under mild conditions over 10-180 min.

Use of silica-based homogeneously distributed gold nickel nanohybrid as a stable nanocatalyst for the hydrogen production from the dimethylamine borane.

In this study, the effects of silica-based gold-nickel (AuNi@SiO2) nanohybrid to the production of hydrogen from dimethylamine borane (DMAB) were investigated. AuNi@SiO2 nanohybrid constructs were prepared as nanocatalysts for the dimethylamine borane dehydrogenation. The prepared nanohybrid structures were exhibited high catalytic activity and a stable form. The resulting nanohybrid, AuNi@SiO2 as a nanocatalyst, was tested in the hydrogen evolution from DMAB at room temperature. The synthesized nanohybrids were characterized using some analytical techniques. According to the results of the characterization, it was observed that the catalyst was in nanoscale and the gold-nickel alloys showed a homogenous distribution on the SiO2 surface. After characterization, the turn over frequency (TOF) of nanohybrid prepared for the production of hydrogen from dimethylamine was calculated (546.9 h-1). Also, the prepared nanohybrid can be used non-observed a significant decrease in activity even after the fifth use, in the same reaction. In addition, the activation energy (Ea) of the reaction of DMAB catalyzed AuNi@SiO2 nanohybrid was found to be 16.653 ± 1 kJmol-1 that facilitated the catalytic reaction. Furthermore, DFT-B3LYP calculations were used on the AuNi@SiO2 cluster to investigate catalyst activity. Computational results based on DFT obtained in the theoretical part of the study support the experimental data.

Palladium supported on polypyrrole/reduced graphene oxide nanoparticles for simultaneous biosensing application of ascorbic acid, dopamine, and uric acid.

In this study, we report a facile and effective production process of palladium nanoparticles supported on polypyrrole/reduced graphene oxide (rGO/Pd@PPy NPs). A novel electrochemical sensor was fabricated by incorporation of the prepared NPs onto glassy carbon electrode (GCE) for the simultaneous detection of ascorbic acid (AA), dopamine (DA) and uric acid (UA). The electrodes modified with rGO/Pd@PPy NPs were well decorated on the GCE and exhibited superior catalytic activity and conductivity for the detection of these molecules with higher current and oxidation peak intensities. Simultaneous detection of these molecules was achieved due to the high selectivity and sensitivity of rGO/Pd@PPy NPs. For each biomolecule, well-separated voltammetric peaks were obtained at the modified electrode in cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements. Additionally, the detection of these molecules was performed in blood serum samples with satisfying results. The detection limits and calibration curves for AA, DA, and UA were found to be 4.9 × 10-8, 5.6 × 10-8, 4.7 × 10-8 M (S/N = 3) and ranging from 1 × 10-3 to 1.5 × 10-2 M (in 0.1 M PBS, pH 3.0), respectively. Hereby, the fabricated rGO/Pd@PPy NPs can be used with high reproducibility, selectivity, and catalytic activity for the development of electrochemical applications for the simultaneous detection of these biomolecules.

Highly monodisperse Pd-Ni nanoparticles supported on rGO as a rapid, sensitive, reusable and selective enzyme-free glucose sensor.

In this work, highly monodispersed palladium-nickel (Pd-Ni) nanoparticles supported on reduced graphene oxide (rGO) were synthesized by the microwave-assisted methodology. The synthesized nanoparticles were used for modification of a glassy carbon electrode (GCE) to produce our final product as PdNi@rGO/GCE, which were utilized for non-enzymatic detecting of glucose. In the present study, electrochemical impedance spectroscopy (EIS), chronoamperometry (CA) and, cyclic voltammetry (CV) methods were implemented to investigate the sensing performance of the developed glucose electrode. The modified electrode, PdNi@rGO/GCE, exhibited very noticeable results with a linear working range of 0.05-1.1 mM. Moreover, an ultralow detection limit of 0.15 µM was achieved. According to the results of amperometric signals of the electrodes, no significant change was observed, even after 250 h of operation period. In addition, the highly monodisperse PdNi@rGO/GCE was utilized to electrochemical detection of glucose in real serum samples. In light of the results, PdNi@rGO/GCE has shown an excellent sensing performance and can be used successfully in serum samples for glucose detection and it is suitable for practical and clinical applications.

Composites of Platinum-Iridium Alloy Nanoparticles and Graphene Oxide for the Dimethyl Amine Borane (DMAB) dehydrogenation at ambient conditions: An Experimental and Density Functional Theory Study.

In this paper, we present the synthesis, characterization, catalytic and computational studies of Composites of Platinum-Iridium Alloy Nanoparticles and Graphene Oxide (PtIr@GO) for dimethylamine borane (DMAB) dehydrogenation. The prepared PtIr@GO nanocatalysts were synthesized using an ethanol super-hydride method, and the characterization procedures for PtIr@GO alloy nanoparticles were carried out by various advanced spectroscopic methods like X-ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Transmission Electron Microscopy(TEM) and high-resolution transmission electron microscopy (HRTEM). Additionally, catalytic activity, reusability, substrate concentration, and catalyst concentration experiments were performed for DMAB dehydrogenation catalyzed by PtIr@GO alloy nanomaterials. According to the results obtained in this study, PtIr@GO NPs catalyst was found to be active and reusable for the DMAB even at ambient conditions. Besides, DFT-B3LYP calculations have been utilized on PtIr@GO cluster to reveal the prepared catalyst activity. The calculated findings based on DFT was found to be a good agreement with experimental results.

Composites of Bimetallic Platinum-Cobalt Alloy Nanoparticles and Reduced Graphene Oxide for Electrochemical Determination of Ascorbic Acid, Dopamine, and Uric Acid.

The ultimate aim of this study is to produce a composite of bimetallic platinum-cobalt nanoparticles and reduced graphene oxide (Pt-Co@rGO) based biosensor for the detection of ascorbic acid (AA), dopamine (DA) and uric acid (UA). Those are biologically important molecules with the key functions for the human body. Pt-Co@rGO was synthesized using a microwave-assisted technique and utilized for the production of a highly sensitive and stable electrochemical biosensor. Detailed spectral XPS and Raman analysis, XRD, and TEM/HR-TEM characterization were also studied. Due to the superior activity and excellent conductivity of rGO, well-separated oxidation peaks of these biomolecules is proven by DPV (differential pulse voltammetry) and CV (cyclic voltammetry) measurements. The prepared Pt-Co@rGO-based biosensor showed high electrochemical activity, a broad linear response, high sensitivity, and acceptable limit of detection values for individual and simultaneous determination of AA, DA, and UA, under optimized conditions. The linear range of Pt-Co@rGO was found to be 170-200; 35-1500 and 5-800 µM for AA, DA, and UA, respectively. Moreover, the detection limit of the prepared composite was calculated as 0.345; 0.051; 0.172 µM for AA, DA, and UA, respectively. In the field of electrochemical biosensors, Pt-Co@rGO based sensor is highly promising due to its superior sensitivity and good selectivity properties.

Multiwalled carbon nanotube-based nanosensor for ultrasensitive detection of uric acid, dopamine, and ascorbic acid.

A novel multiwalled carbon nanotube (MWCNT) based sensor was fabricated as a highly precise and stable electrochemical sensor. The synthesized sensor which consists of ZnNi bimetallic nanoalloy called the ZnNi NPs@f-MWCNT sensor, have been used for the simultaneous detection of uric acid (UA), dopamine (DA) and ascorbic acid (AA). The ZnNi NPs@f-MWCNT sensor obtained based on the microwave irradiation process, and its characterization was performed by using several physical techniques such as XRD, XPS, TEM, Raman, etc. The characterization showed that this sensor has excellent properties such as rich pore channels, excellent structural durability, and large surface area. These properties facilitated mass transfer and electron conductions. It was observed that the obtained sensor gave high electrochemical activity and wide linear responses (0.3-1.1 mM AA, 0.2-1.2 mM DA, 0.2-1.1 mM UA) in the detection of uric acid (UA), dopamine (DA) and ascorbic acid (AA). In addition to these properties, it has been found that the sensor has excellent anti-interferents properties towards AlCl3, KCl3, glucose, etc. and ZnNi NPs@f-MWCNT sensor was further applied to determine uric acid (UA), dopamine (DA) and ascorbic acid (AA) in real samples.

Use of the monodisperse Pt/Ni@rGO nanocomposite synthesized by ultrasonic hydroxide assisted reduction method in electrochemical nonenzymatic glucose detection.

An electrochemical non-enzymatic sensor was developed for the detection of glucose based on an electrode modified with monodisperse platinum-nickel nanocomposites-decorated on reduced graphene oxide (Pt/Ni@rGO) which was synthesized using a new ultrasonic hydroxide assisted reduction method. Because the nanocomposites prepared by using NaOH (OH- ligands) are much smaller nanocomposites on the supports compared to the ones without OH- ligands. Such a monodisperse Pt/Ni@rGO nanocomposites-based electrode exhibited a high electrochemical activity for electrocatalytic oxidation of glucose in alkaline solution. Amperometric analysis showed a glucose sensitivity of 171.92 µA/mM cm2 of, the detection limit of 6.3 µM and a linear range of 0.02-5.0 mM glucose concentration. Fabricated sensor platform demonstrated long-term stability and good reproducibility, in addition to high selectivity.

Highly efficient polymer supported monodisperse ruthenium-nickel nanocomposites for dehydrocoupling of dimethylamine borane.

In the present study, highly effective and reusable monodisperse ruthenium-nickel (Ru-Ni) nanomaterials supported on poly(N-vinyl-2-pyrrolidone) (Ru-Ni@PVP) were synthesized (3.51 ±â€¯0.38 nm) by a facile sodium-hydroxide-assisted reduction method; Ru and Ni reduction in PVP solution was accomplished. The prepared nanocomposites were characterized by TEM, HRTEM, XRD, and XPS and performed as a catalyst for dehydrocoupling of dimethylamine-borane (DMAB). It was found that Ru-Ni nanomaterials are one of the most active catalysts at low concentrations and temperature for dehydrocoupling of DMAB. This catalyst with its turnover frequency of 458.57 h-1 exhibits one of the best results among all the catalysts prepared in the literature for dehydrocoupling of DMAB. Significantly low Ea value (36.52 ±â€¯3 kJ mol-1) was also found for dehydrocoupling of DMAB.

Highly efficient monodisperse Pt nanoparticles confined in the carbon black hybrid material for hydrogen liberation.

Dimethylamine borane (DMAB) has been considered as one of the important hydrogen sources with a simple process by the help of the efficient catalyst. For this purpose, herein, platinum nanoparticles (Pt NPs), placed inside carbon black hybrid (Pt NPs@CBH), activated carbon (Pt NPs@AC) and Vulcan carbon (Pt NPs@VC), have been prepared as highly monodisperse catalysts for dehydrogenation reactions of DMAB at room temperature. The morphological and physical structure of the monodisperse catalysts have been identified by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) etc. The typical face-centered cubic (fcc) structure of the all prepared catalysts was verified from X-ray diffractogram. All prepared catalytic materials were measured as high-performance catalysts for dehyrocoupling of DMAB; but, Pt NPs@CBH catalyst indicated the better catalytic activity compared to the other prepared ones. Easy utilization at very small concentrations and temperature, monodisperse Pt NPs@CBH perform an eye-catching catalytic activity with providing one of the best TOF (70.28 h-1) and Ea (93.56 ±â€¯2 kJ/mol) for dehydrocoupling of DMAB.

Highly sensitive glucose sensor based on monodisperse palladium nickel/activated carbon nanocomposites.

Glucose enzyme biosensors have been used for a variety of applications such as medical diagnosis, bioprocess engineering, beverage industry and environmental scanning etc. and there is still a growing interest in glucose sensors. For this purpose, addressed herein, as a novel glucose sensor, highly sensitive activated carbon (AC) decorated monodisperse nickel and palladium alloy nanocomposites modified glassy carbon electrode (Ni-Pd@AC/GCE NCs) have been synthesized by in-situ reduction technique. Raman Spectroscopy (RS), X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), cyclic voltammetry (CV) and chronoamperometry (CA) were used for the characterization of the prepared non-enzymatic glucose sensor. The characteristic sensor properties of the Ni-Pd@AC/GCE electrode were compared with Ni-Pd NCs/GCE, Ni@AC/GCE and Pd@AC/GCE and the results demonstrate that the AC is very effective in the enhancement of the electrocatalytic properties of sensor. In addition, the Ni-Pd@AC/GCE nanocomposites showed a very low detection limit of 0.014 µM, a wide linear range of 0.01 mM-1 mM and a very high sensitivity of 90 mA mM-1 cm-2. Furthermore, the recommended sensor offer the various advantageous such as facile preparation, fast response time, high selectivity and sensitivity. Lastly, monodisperse Ni-Pd@AC/GCE was utilized to detect glucose in real sample species.

A hydrogen peroxide sensor based on TNM functionalized reduced graphene oxide grafted with highly monodisperse Pd nanoparticles.

Addressed herein, we report the synthesis and characterization of a tert-nonyl mercaptan (TNM) functionalized reduced graphene oxide (rGO) supported palladium (Pd) nanoparticles (NPs) (Pd/TNM@rGO) as electrochemical sensor. The highly monodisperse Pd/TNM@rGO nanocomposite was applied for electrochemical determination of hydrogen peroxide (H2O2) at a potential range of -0.6 to +0.8 V. The Pd/TNM@rGO sensor demonstrated very high activity, sensitivity, reusability and durability toward H2O2 sensing. The well dispersed Pd/TNM@rGO nanocomposite has been characterized by using several analytical techniques such as, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS) and electrochemical impedance spectroscopy (EIS). The catalytic performance of prepared biosensor was also characterized by using cyclic voltammetry (CV) and chronoamperometry (CA) methods. The proposed H2O2 biosensor showed a broad linear range up to 12 mM, and a very low detection limit of 0.0025 µM, with a quick response time of less than 10 s. Additionally, the biosensor exhibited great capability, reproducibility and durability for the examination of H2O2.

Rapid, sensitive, and reusable detection of glucose by highly monodisperse nickel nanoparticles decorated functionalized multi-walled carbon nanotubes.

Addressed herein, functionalized multi-walled carbon nanotube (MWCNT) supported highly monodisperse nickel nanoparticles modified on glassy carbon electrode (Ni@f-MWCNT/GCE) were synthesized through microwave assisted method and examined for non-enzymatic glucose sensing in ionic liquids by cyclic voltammetry and chronoamperometry. The results of Ni@f-MWCNT/GCE electrode were compared with Ni NPs/GCE electrode and the results revealed that f-MWCNTs increased the electrocatalytic properties of Ni nanoparticles regarding glucose oxidation. They also demonstrated a good linear span of 0.05-12.0mM and a detection boundary of 0.021µM. Specifically, in the amperometric signal of the electrodes after 200th cycles, no major change was observed. This non-enzymatic glucose sensor presents one of the record electrocatalytic activity, stability and response towards glucose under the optimized situations. As a result, prepared novel Ni@f-MWCNT/GCE was utilized to detect glucose in real serum species.