Flower‐like Ni(II)‐based Metal‐organic Framework‐decorated Ag Nanoparticles: Fabrication,Characterization and Electrochemical Detection of Glucose

Glucose concentration monitoring is important for the prevention, diagnosis and treatment of diabetes. In this work, a composite material of AgNPs/MOF‐74(Ni) was prepared for electrochemical determination of glucose. AgNPs/MOF‐74(Ni) was characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X‐ray photoelectron spectroscopy (XPS). The electrochemical properties of the glassy carbon electrodes modified with the AgNPs/MOF‐74(Ni) composites were characterized by cyclic voltammetry (CV) and current‐time curve (I‐t curve) with three electrode system. The determination of glucose with the electrode modified by AgNPs/MOF‐74(Ni) has a linear range of 0.01～4 mM with the correlation coefficient (R²) of 0.994. The detection limit is 4.7 μM (S/N=3) and the sensitivity is 1.29 mA ? mM^?1 ? cm^?2. In addition, this sensing system possesses reasonable reproducibility and stability. The good performance of electrochemical determination for glucose is attributed to the concerted effect of silver nanoparticles and MOF‐74(Ni) on the promotion of glucose oxidation     

A Novel Enzymatic Glucose Biosensor and Nonenzymatic Hydrogen Peroxide Sensor Based on (3‐Aminopropyl) Triethoxysilane Functionalized Reduced Graphene Oxide

In the present study, a novel enzymatic glucose biosensor using glucose oxidase (GOx) immobilized into (3‐aminopropyl) triethoxysilane (APTES) functionalized reduced graphene oxide (rGO‐APTES) and hydrogen peroxide sensor based on rGO‐APTES modified glassy carbon (GC) electrode were fabricated. Nafion (Nf) was used as a protective membrane. For the characterization of the composites, Fourier transform infrared spectroscopy (FTIR), X‐ray powder diffractometer (XRD), and transmission electron microscopy (TEM) were used. The electrochemical properties of the modified electrodes were investigated using electrochemical impedance spectroscopy, cyclic voltammetry, and amperometry. The resulting Nf/rGO‐APTES/GOx/GC and Nf/rGO‐APTES/GC composites showed good electrocatalytical activity toward glucose and H₂O₂, respectively. The Nf/rGO‐APTES/GC electrode exhibited a linear range of H₂O₂ concentration from 0.05 to 15.25 mM with a detection limit (LOD) of 0.017 mM and sensitivity of 124.87 μA mM⁻¹ cm⁻². The Nf/rGO‐APTES/GOx/GC electrode showed a linear range of glucose from 0.02 to 4.340 mM with a LOD of 9 μM and sensitivity of 75.26 μA mM⁻¹ cm⁻². Also, the sensor and biosensor had notable selectivity, repeatability, reproducibility, and storage stability.     

A Novel Electrochemical Sensor Based on Copper‐based Metal‐Organic Framework for the Determination of Dopamine

A glassy carbon electrode (GCE) modified with a copper‐based metal‐organic framework (MOF) [HKUST‐1, HKUST‐1 = Cu₃(BTC)₂ (BTC = 1,3,5‐benzenetricarboxylicacid)] was developed as a highly sensitive and simple electrochemical sensor for the determination of dopamine (DA). The MOF was prepared by a hydrothermal process, and the morphology and crystal phase of the MOF were characterized by scanning electron microscopy (SEM) and X‐ray diffraction (XRD), respectively. Meanwhile, the electrochemical performance was investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). Under optimized conditions, the modified electrode showed excellent electrocatalytic activity and high selectivity toward DA. The linear response range was from 5.0 × 10⁻⁷ to 1.0 × 10⁻⁴ M and the detection limit was as low as 1.5 × 10⁻⁷ M. Moreover, the electrochemical sensor was used to detect DA in real samples with excellent results. MOF‐based sensors hold great promise for routine sensing applications in the field of electrochemical sensing.     

Fabrication of Hierarchically Structured MOF‐Co3O4 on Well‐aligned CuO Nanowire with an Enhanced Electrocatalytic Property

Engineering appropriate shape and size of three‐dimensional inorganic nanostructures materials is of one the main critical problems in pursuing high‐performance electrode materials. Herein, we fabricate a metal‐organic framework derived cobalt oxide (Co₃O₄) are grown on copper oxide nanowire (CuO NWs) supported on the surface of 3D copper foam substrate. The highly aligned CuO NWs were prepared by using electrochemical anodization of copper foam in ambient temperature and followed by MOF Co₃O₄ was grown via a simple in situ solution deposition then consequent calcination process. The obtained binder‐free 3D CuO NWs@Co₃O₄ nanostructures were further characterized by using X‐ray diffraction, X‐ray photoelectron spectroscopy, field‐emission scanning electron microscopy, and transmission electron microscopy. Furthermore, electrochemical sensing of glucose was studied by using Cyclic Voltammetry, and chronoamperometry techniques. Interestingly, 3D CuO NWs@Co₃O₄ electrode exhibits excellent performance for the oxidation of glucose compared with individual entities. The proposed sensor shows wide linear ranges from 0.5 μM to 0.1 mM with the sensitivity of 6082 μA/μM and the lowest detection limit (LOD) of 0.23 μM was observed with the signal to noise ratio, (S/N) of 3. The superior catalytic oxidation of glucose mainly is endorsed by the excellent electrical conductivity and synergistic effect of the Co₃O₄ and CuO NWs.     

Electrochemical Investigation of Glucose on a Highly Sensitive Nickel‐Copper Modified Pencil Graphite Electrode

Novel nickel‐copper modified pencil graphite electrode (Ni?Cu/PGE) was fabricated and used as non‐enzymatic sensor for glucose determination. Ni and copper were electrodeposited on PGE using cyclic voltammetry. Morphology and composition of the modified PGE electrode were characterized by field‐emission gun scanning electron microscopy (FEG‐SEM), energy‐dispersive X‐ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FT‐IR). Electrochemical oxidation of glucose was evaluated by cyclic voltammetry as well as by amperometry. Electrochemical measurements indicate that the Ni?Cu/PGE exhibits a high sensitivity of 2951 μA mM^?1 cm^?2, and a low detection limit of 0.99 μM which are, respectively, three times higher and twice lower than that on Ni/PGE prepared in the same conditions. Moreover, Ni?Cu/PGE exhibits a wider linear range from 1 to 10000 μM with a rapid response time within 2 s. Moreover, Ni?Cu/PGE showed a remarkable stability. The electrode was successfully applied for determination of glucose concentration in human blood without significant interference from potential endogenic interferents. The good applicability of the elaborated sensor made Ni?Cu/PGE promising for the development of effective and inexpensive non‐enzymatic glucose sensor.     

Glucose Electro‐oxidation on Graphite Electrode Modified with Nickel/Chromium Nanoparticles

In this study, an available and inexpensive graphite substrate, was easily modified with Ni/Cr nanoparticles via electrodeposition technique in a very short time (3 min) and used as an electrocatalyst for glucose oxidation in alkaline solution. Graphite electrode modified with Ni/Cr nanoparticles demonstrated an outstanding electrocatalytic performance to glucose oxidation in comparison to examined Ni‐based electrodes or even different materials in other reports. It is noteworthy to mention that adding a little Cr led to a synergistic effect with Ni; accordingly, the presence of Cr not only resulted in a greater adsorption of glucose molecules by chromium oxide but also boosted conductivity of the nickel oxide because of the enhancement of Ni(III) amount. The electrochemical studies were performed by cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The morphology and structure of catalyst layer was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD) and energy dispersive x‐ray spectroscopy (EDS). The linear range of the electrode by cyclic voltammetry was between 2–31 mM with a high sensitivity of 2094 μA cm^?2 mM^?1. The repeatability and reproducibility of the proposed electrode was examined in glucose solution which were 0.3 % and 4.7 %, respectively. According to the low cost, ease and fast preparation, good repeatability and high sensitivity, this electrode can be a good candidate for nonenzymatic glucose oxidation.     

Cobalt nanoparticles anchored to porous silicon as a novel modifier for the construction of enzyme‐free hydrogen peroxide screen‐printed sensor

In this work, a screen‐printed carbon electrode (SPCE) was modified with a cobalt/porous silicon (Co@PSi) nanocomposite powder to develop a nonenzymatic sensor for the detection of hydrogen peroxide. The Co@PSi nanocomposite was synthesized through the chemical reaction between silicon powder in a HF/HNO₃ solution and cobalt cations. In this process, cobalt nanoparticles were anchored on the porous silicon. The structure and morphology of the synthesized nanocomposite were investigated by X‐ray diffraction, Fourier transform infrared spectroscopy, X‐ray photoemission spectroscopy, energy dispersive X‐ray spectroscopy, and field‐emission scanning electron microscopy. The constructed nonenzymatic, screen‐printed sensors based on the Co@PSi nanocomposite showed perfect electrocatalytic oxidation response to hydrogen peroxide over the range 1–170 and 170–3,770 μmol/L with the limit of detection of 0.8 μmol/L. In addition, the Co@PSi‐SPCE sensor exhibited good selectivity for the determination of H₂O₂ in the presence of common interfering species including glucose, ascorbic acid, uric acid, dopamine, nitrate, and nitrite ions. The constructed electrochemical sensor was successfully used for the determination of H₂O₂ in real samples.     

Dispersed Nickel Nanoparticles on Flower‐like Layered Nickel‐Cobalt Double Hydroxides for Non‐enzymic Amperometric Sensing of Glucose

The article describes the preparation of supported nickel nanoparticles (NiNPs) by partial reduction of Ni,Co‐layered double hydroxide (NiCo‐LDH). The nanocomposites were characterized by X‐ray diffraction and their morphology and composition were characterized by scanning electron microscopy and transmission electron microscopy. The electrochemical properties of the nanocomposite were explored by cyclic voltammetry and amperometry, which revealed significant electrocatalytic behavior towards the oxidation of glucose. The resulted non‐enzymatic glucose sensor has a linear response to glucose in the 5.0 μM to 14.8 mM concentration range, a low detection limit of 1.6 μM, high sensitivity, and excellent selectivity.     

Nickel Hydroxide and Intercalated Graphene with Ionic Liquid Nanocomposite‐modified Electrode for Sensing of Glucose

A novel non‐enzymatic glucose sensor based on nickel hydroxide and intercalated graphene with ionic liquid (G‐IL) nanocomposite modified glass carbon electrode was fabricated. Scanning electron microscope, Fourier transform infrared spectra and energy dispersive X‐ray spectroscopy of the nanocomposite confirmed the morphology and ingredient of Ni(OH)₂ as well as G‐IL. Moreover, experimental results of cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry indicated the sensing properties of Ni(OH)₂ at Ni(OH)₂/G‐IL modified electrode towards the typical electrocatalytic oxidation process of glucose at 0.43 V in 0.10 M NaOH. The current response was linearly related to glucose concentration in a range from 0.5 to 500 μM with a detection limit of 0.2 μM (S/N = 3) and sensitivity of 647.8 μA mM^?1 cm^?2. The response time of the sensor to glucose was less than 2 s. This work may be expected to develop an excellent electrochemical sensing platform of G‐IL as a catalysis carrier.     

MWCNTs/Ionic Liquid/Graphene Quantum Dots Nanocomposite Coated with Nickel‐Cobalt Bimetallic Catalyst as a Highly Selective Non‐enzymatic Sensor for Determination of Glucose

In this work, a glassy carbon electrode (GCE) was modified with multiwall carbon nanotubes/ionic liquid/graphene quantum dots (MWCNTs/IL/GQDs) nanocomposite. Then, the nanocomposite was decorated with nickel‐cobalt nanoparticles (Ni?Co NPs), and it was used as a non‐enzymatic glucose sensor. Field emission scanning electron microscopy, X‐ray diffraction spectroscopy, and energy dispersive spectroscopy were employed to prove the electrodeposition of the Ni?Co NPs on the surface of MWCNTs/IL/GQDs/GCE. Also, cyclic voltammetric and amperometric methods were utilized for the investigation of the electrochemical behaviour of the Ni?Co NPs/MWCNTs/IL/GQDs/GCE for glucose oxidation. The novel amperometric sensor displayed two linear ranges from 1.0 to 190.0 μmol L^?1 and 190.0 to 4910 μmol L^?1 with a low detection limit of 0.3 μmol L^?1 as well as fast response time (2 s) and high stability. Also, the sensor showed good selectivity for glucose determination in the presence of ascorbic acid, citric acid, dopamine, uric acid, fructose, and sucrose, as potential interference species. Finally, the performance of the proposed sensor was investigated for the glucose determination in real samples. Ni?Co NPs/MWCNTs/IL/GQDs/GCE showed good sensitivity and excellent selectivity.     

A Novel Electrochemical Method for the Analysis of Hydrogen Peroxide with the Use of a Glassy Carbon Electrode Modified by a Prussian Blue/Copper‐Gold Bimetallic Nanoparticles Hybrid Film

A novel Prussian blue/copper‐gold bimetallic nanoparticles hybrid film modified electrode was prepared by electrochemical deposition on a glassy carbon electrode (PB/Cu‐AuNPs/GCE). Morphology and electrochemistry of this electrode were studied by UV‐vis spectroscopy, scanning electron microscopy, X‐ray diffraction, cyclic voltammetry and electrochemical impedance spectroscopy. The sensor showed significantly better electrocatalytic activity for the reduction of hydrogen peroxide in comparison with the single PB/GCE and PB/AuNPs/GCE. This was attributed to the synergistic effect of PB and Cu‐Au bimetallic nanoparticles. Also, the sensor demonstrated an overall high level of performance for the analysis of H₂O₂ in the concentration range from 0.002 to 0.84 mM.     

Preparation and Characterization of a Tin Pentacyanonitrosylferrate‐Modified Carbon Ceramic Electrode: Application to Electrocatalytic Oxidation and Amperometric Detection of L‐Cysteine

The sol‐gel technique was used to construct tin pentacyanonitrosylferrate (SnPCNF) modified composite carbon ceramic electrode (CCE). This involves two steps: construction of CCE containing metallic Sn powder and then electrochemical creating of SnPCNF on the surface of CCE. The SnPCNF modified CCE (SnPCNFlCCE) was characterized by energy‐dispersive X‐ray (EDX), FTIR and cyclic voltammetry (CV) techniques. The SnPCNF film showed electrocatalytic activity toward the oxidation of L ‐cysteine. A linear calibration plot was obtained over the L ‐cysteine concentration range 1–51 μM using chronoamperometry. L ‐cysteine was determined amperometrically at the surface of this modified electrode. The detection limit (for a signal to noise of 3) and sensitivity were found to be 0.62 μM and 126 μA/mM, respectively.     

Ni3S2 Supported on Porous Ball‐milled Silicon,a Highly Selective Electrochemical Sensor for Glucose Determination

In this work, an electrochemical sensor based on Ni₃S₂ nanoparticles supported on porous ball‐milled silicon was fabricated for measuring glucose. At first, the glassy carbon electrode (GCE) surface was modified by Ni₃S₂ nanoparticles supported on a porous ball‐milled silicon substrate. To characterize the modified electrode, N₂ adsorption‐desorption isotherms and BHJ, transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDX), elemental mapping and X‐ray diffraction (XRD) were used. In the following, the effective parameters on the sensor response such as pH, NaOH concentration, catalyst concentration, applied potential, and rotational speed of the electrode were optimized using cyclic voltammetric (CV) and hydrodynamic amperometric methods. Under the optimal conditions, the calibration curve was plotted using the hydrodynamic amperometric method. Three linear regions were obtained from 0.5–134, 134–1246, and 1246–3546 μM, with a detection limit of 0.2 μM for glucose. Finally, the proposed method was used for measuring glucose levels in human blood serums.     

An enhanced Nonenzymatic Electrochemical Glucose Sensor Based on Copper‐Palladium Nanoparticles Modified Glassy Carbon Electrodes

Novel copper‐palladium nanoparticles modified glassy carbon electrodes (Cu−Pd/GC) with enhanced nonenzymatic sensing for glucose were facilely prepared by one‐step electrodeposition. The structure and composition of the prepared nanoparticles were characterized by XRD, SEM, TEM and EDS, respectively. The electrode modified process was characterized by electrochemical impedance spectroscopy. Cyclic voltammetry and chronoamperometric experiments were used to evaluate the electrocatalytic activities of the electrodes toward glucose. The surface morphology and the electrocatalytic activities of Cu−Pd/GC was compared to Pd and Cu nanoparticles modified glassy carbon electrodes (Pd/GC and Cu/GC), respectively. Thanks to homogeneous distribution of Cu−Pd nanoparticles and the synergistic effect of Cu and Pd atoms, Cu−Pd/GC exhibited the highest sensitivity (298 μA mM⁻¹ cm⁻²) and the widest linear amperometric response (0.01 mM to 9.6 mM, R²=0.996) toward glucose compared to Pd/GC and Cu/GC. The detection limit of Cu−Pd/GC was 0.32 μM (S/N=3). In addition, the as‐prepared Cu−Pd/GC glucose sensor also exhibited exceptional capabilities of anti‐interference, reproducibility and long‐term stability. The as‐prepared sensor was also evaluated for determination of glucose concentration in human blood serum samples, which exhibited high reliability and accuracy, having great potential in clinical application.     

Engineering a Cu‐MOF Nano‐Catalyst by using Post‐Synthetic Modification for the Preparation of 5‐Substituted 1H‐Tetrazoles

A new nano scale Cu‐MOF has been obtained via post‐synthetic metalation by immersing a Zn‐MOF as a template in DMF solutions of copper(II) salts. The Cu‐MOF serves as recyclable nano‐catalyst for the preparation of 5‐substituted 1H‐tetrazoles via [3 + 2] cycloaddition reaction of various nitriles and sodium azide in a green medium (PEG). The post‐synthetic metalated MOF were characterized by FT‐IR spectroscopy, powder X‐ray diffraction (PXRD), atomic absorption spectroscopy (AAS), and energy dispersive X‐ray spectroscopy (EDX) techniques. The morphology and size of the nano‐catalyst were determined by field emission scanning electron microscopy (FE‐SEM).     

Highly Sensitive Hydrazine Sensor Based on Co(OH)2 Nanoflakes Electrochemically Deposited on MWCNTs

We delineate the electrochemical preparation of cobalt hydroxide nanoflakes Co(OH)₂ NFs on multi‐walled carbon nanotubes (MWCNTs) by potentiostatic methods. The preparation was done on the surface of glassy carbon electrode (GCE). The prepared nanocomposite was characterized by field emission scanning electron microscopy (FESEM), X‐ray diffraction spectroscopy (XRD) and X‐ray photo electron spectroscopy (XPS). The resulting f‐ MWCNTs/Co(OH)₂ NFs modified GCE exhibits a good electrocatalytic activity for the oxidation of hydrazine in terms of decreasing over potential and increasing peak current. The modified electrode holds good in the linear range from 0.5 to 15.5 μM with limit of detection as 87.5 nM. The sensitivity of our modified electrode is calculated to be 5733 μA/mM cm‐2. Remarkably, the obtained LOD value of our sensor is very lower compared to the recommended concentration of hydrazine in water by World health organization (WHO) and Environmental protective agency (EPA). The modified electrode detects hydrazine selectively even in the presence of common interferants. Various water samples were chosen to study the practical feasibility of our sensor. The sensor also exhibited an appreciable stability, repeatability and reproducibility.     

Electroanalytical Determination of Paracetamol Using Pd Nanoparticles Deposited on Carboxylated Graphene Oxide Modified Glassy Carbon Electrode

The study presents a novel paracetamol (PA) sensor based on Pd nanoparticles (PdNPs) deposited on carboxylated graphene oxide (GO?COOH) and nafion (Nf) modified glassy carbon electrode (GCE). The morphologies of the as prepared composites were characterized using high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and fourier transform infrared spectroscopy (FTIR). The experimental results demonstrated that Nf/GO?COOPd displayed excellent electrocatalytic response to the oxidation PA. The linear range was 0.04–800 μM for PA with limit of detection of 0.012 μM and excellent sensitivity of 232.89 μA mM^?1 cm^?2. By considering the excellent performance of Nf/GO?COOPd composite such as wider linear range, lower detection, better selectivity, repeatability, reproducibility, and storage stability, the prepared composite, especially GO?COOH support, with satisfactory electrocatalytic properties was a promising material for the modification of electrode material in electrochemical sensor and biosensor field.     

Facile Synthesis of Leaf‐Like CuO Nanoparticles and Their Application on Glucose Biosensor

An efficient amperometric biosensor based on well‐crystallized leaf‐like CuO nanoparticles for detecting glucose has been proposed. The leaf‐like CuO nanoparticles, synthesized by a simple one‐step hydrothermal method, were characterized by X‐ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM) for the morphology study. Under the optimal condition, the electrochemical behaviour of the leaf‐like CuO nanoparticles modified electrode for detection of glucose exhibited high sensitivity of 246 µA/mM/cm², short response time (within 5 s), linear dynamic range from 1.0 to 170 µM (R²=0.9995), and low limit of detection (LOD) (S/N=3) of 0.91 µM. The high sensitivity, good reproducibility, stability, and fast amperometric sensing towards oxidation of glucose, make this biosensor promising for future application.     

High Performance Non‐enzymatic Glucose Sensor Based on One‐Step Electrodeposited Nickel Sulfide

Nanostructured NiS thin film was prepared by a one‐step electrodeposition method and the structural, morphological characteristics of the as‐prepared films were analyzed by X‐ray diffractometry (XRD), field emission scanning electron microscopy (FESEM) and energy dispersive X‐ray analysis (EDAX). The electrocatalytic activity of NiS thin film towards glucose oxidation was investigated by fabricating a non‐enzymatic glucose sensor and the sensor performance was studied by cyclic voltammetry (CV) and amperometry. The fabricated sensor showed excellent sensitivity and low detection limit with values of 7.43 μA μM ^?1 cm^?2 and 0.32 μM , respectively, and a response time of <8 s.     

A New Amperometric Hydrazine Sensor Based on Prussian Blue/Single‐walled Carbon Nanotube Nanocomposites

A slow reaction process has been successfully used to synthesize Prussian blue/single‐walled carbon nanotubes (PB/SWNTs) nanocomposites. Electrochemical and surface characterization by cyclic voltammetry (CV), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV‐vis absorption spectroscopy, Fourier transform infrared (FTIR) spectroscopy and X‐ray diffraction (XRD) confirmed the presence of PB nanocrystallites on SWNTs. PB/SWNTs modified glassy carbon electrode (GCE) exhibits efficient electron transfer ability and high electrochemical response towards hydrazine. The fabricated hydrazine sensor showed a wide linear range of 2.0×10^?6–6.0×10^?3 M with a response time less than 4 s and a detection limit of 0.5 μM. PB/SWNTs modified electrochemical sensors are promising candidates for cost‐effective in the hydrazine assays.