Natarajan Karikalan

Modern Approach to the Synthesis of Ni(OH)2 Decorated Sulfur Doped Carbon Nanoparticles for the Nonenzymatic Glucose Sensor

As a growing aspect of materials science, there are an enormous number of synthesis routes that have been identified to produce materials, particularly through simple methodologies. In this way, the present study focuses on the easiest way to prepare sulfur doped carbon nanoparticles (SDCNs) using a flame synthesis method and has also demonstrated a novel route to synthesize Ni(OH)2 decorated SDCNs by a simple adsorption cum precipitation method. The SDCNs are alternative candidates to prestigious carbon materials such as graphene, carbon nanotubes, and fullerenes. Moreover, SDCNs provide excellent support to the Ni(2+) ion adsorption and initiate the formation of Ni(OH)2. The formation of Ni(OH)2 on the SDCN matrix was confirmed by Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), selected area diffraction pattern (SAED), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). After these meticulous structural evaluations, we have described the mechanism for the formation of Ni(OH)2 on an SDCN matrix. The as-prepared Ni(OH)2 decorated SDCN nanocomposites were used as an electrode material for nonenzymatic glucose sensors. The fabricated glucose sensor exhibited a wide linear concentration range, 0.0001-5.22 mM and 5.22-10.22 mM, and a low-level detection limit of 28 nM. Additionally, it reveals excellent selectivity in the potentially interfering ions and also possesses a good stability. The practicality of the fabricated glucose sensor was also demonstrated toward glucose detection in biological samples.

Electrochemical preparation of activated graphene oxide for the simultaneous determination of hydroquinone and catechol

This paper describes the electrochemical preparation of highly electrochemically active and conductive activated graphene oxide (aGO). Afterwards, the electrochemical properties of aGO was studied towards the simultaneous determination of hydroquinone (HQ) and catechol (CC). This aGO is prepared by the electrochemical activation of GO by various potential treatments. The resultant aGOs are examined by various physical and electrochemical characterizations. The high potential activation (1.4 to -1.5) process results a highly active GO (aGO1), which manifest a good electrochemical behavior towards the determination of HQ and CC. This aGO1 modified screen printed carbon electrode (SPCE) was furnished the sensitive detection of HQ and CC with linear concentration range from 1 to 312μM and 1 to 350μM. The aGO1 modified SPCE shows the lowest detection limit of 0.27μM and 0.182μM for the HQ and CC, respectively. The aGO1 modified SPCE reveals an excellent selectivity towards the determination of HQ and CC in the presence of 100 fold of potential interferents. Moreover, the fabricated disposable aGO1/SPCE sensor was demonstrated the determination of HQ and CC in tap water and industrial waste water.

A voltammetric determination of caffeic acid in red wines based on the nitrogen doped carbon modified glassy carbon electrode

We reported an electrochemical determination of caffeic acid (CA) based on the nitrogen doped carbon (NDC). The described sensor material was prepared by the flame synthesis method, which gave an excellent platform for the synthesis of carbon nanomaterials with the hetero atom dopant. The synthesized material was confirmed by various physical characterizations and it was further characterized by different electrochemical experiments. The NDC modified glassy carbon electrode (NDC/GCE) shows the superior electrocatalytic performance towards the determination of CA with the wide linear concentration range from 0.01 to 350 μM. It achieves the lowest detection limit of 0.0024 μM and the limit of quantification of 0.004 μM. The NDC/GCE-CA sensor reveals the good selectivity, stability, sensitivity and reproducibility which endorsed that the NDC is promising electrode for the determination of CA. In addition, NDC modified electrode is applied to the determination of CA in red wines and acquired good results.

Electrochemical properties of the acetaminophen on the screen printed carbon electrode towards the high performance practical sensor applications

Acetaminophen is a non-steroidal anti-inflammatory drug used as an antipyretic agent for the alternative to aspirin. Conversely, the overdoses of acetaminophen can cause hepatic toxicity and kidney damage. Hence, the determination of acetaminophen receives much more attention in biological samples and also in pharmaceutical formulations. Here, we report a rapid and sensitive detection of the acetaminophen based on the bare (unmodified) screen printed carbon electrode (BSPCE) and its electrochemistry was studied in various pHs. From the observed results, the mechanism of the electro-oxidation of acetaminophen was derived for various pHs. The acetaminophen is not stable in strong acidic and strong alkaline media, which is hydrolyzed and hydroxylated. However, it is stable in intermediate pHs due to the dimerization of acetaminophen. The kinetics of the acetaminophen oxidation was briefly studied and documented in the schemes. In addition, the surface morphology and disorders of BSPCE was probed by scanning electron microscope (SEM) and Raman spectroscopy. Moreover, the BSPCE determined the acetaminophen with the linear concentration ranging from 0.05 to 190μM and the lower detection limit of 0.013μM. Besides that it reveals the good recoveries towards the pharmaceutical samples and shows the excellent selectivity, sensitivity and stability. To the best of our knowledge, this is the better performance compare to the previously reported unmodified acetaminophen sensors.

Three-Dimensional Fibrous Network of Na0.21MnO2 for Aqueous Sodium-Ion Hybrid Supercapacitors

Sodium-ion hybrid supercapacitors are potential energy-storage devices and have recently received enormous interest. However, the development of cathode materials and the use of nonaqueous electrolyte remain a great challenge. Hence, aqueous Na-ion hybrid supercapacitors based on a three-dimensional network of NaMnO2 were developed. The cathode material was synthesized by the electro-oxidation of potassium manganese hexacyanoferrate nanocubes. The oxidized compound was confirmed to be Na0.21 MnO2 by various physical characterization methods. Manganese dioxide is a well-characterized material for aqueous asymmetric pseudocapacitors, but its usage at high operating voltages is limited due to the electrochemical stability of water. Nevertheless, high-potential and high-performance aqueous supercapacitors exhibiting a cell potential of 2.7 V were developed. Further, the practical applicability of an asymmetric supercapacitor based on NaMnO2 (cathode) and reduced graphene oxide (anode) was demonstrated by powering a 2.1 V red LED.

A copper hexacyanocobaltate nanocubes based dopamine sensor in the presence of ascorbic acid

A novel copper hexacyanocobaltate based sensor was developed and its electrocatalytic behavior towards the oxidation of dopamine (DA) was demonstrated. Among the Prussian blue analogues, copper hexacyanocobaltate (CuHCC) exhibits unique electrochemical responses due to its bimetallic combination of copper and cobalt. As-prepared CuHCC shows a well-defined cubic structure with an average size of around 252 nm, which was confirmed by XRD and FE-SEM. Raman spectroscopy confirmed the coordination behavior of both the metal and ligand in CuHCC, which existed as CoIII–CN–CuII and CoII–CN–CuIII. The as-prepared CuHCC was used for the first time in DA detection and provided a better platform as a DA sensor. The electrocatalytic activity of CuHCC towards dopamine was examined by cyclic and differential pulse voltammetry. The CuHCC fabricated sensor shows a wide linear range from 0.1 to 350 μmol L−1 and low detection limit of 19 nmol L−1. The sensor reported herein displays excellent sensitivity, high stability and appreciable reproducibility for DA oxidation.

Studies on the influence of β-cyclodextrin on graphene oxide and its synergistic activity to the electrochemical detection of nitrobenzene

The impact of the β-cyclodextrin (β-CD) on the graphene oxide (GO) was considerably altered the activity of electrochemical sensors. Hence, the present study, we scrutinized the electrocatalytic determination of nitrobenzene (NB) by changing the different loading level of β-CD on GO modified electrodes. The composites were prepared by the simple ultrasonication method and characterized by UV-Visible spectroscopy, infrared spectroscopy and scanning electron microscope. Interestingly, the synergistic electrocatalytic activity was appeared for the 1.2mg β-CD loaded GO (β-CD1.2mg/GO) to the determination of NB whereas bare SPCE, GO and other β-CD loaded GO/SPCE exhibited the lower electrocatalytic activity. The β-CD1.2mg/GO composite modified SPCE was furnished the linear concentration range from 0.5-1000μM and showed the lowest detection limit of 0.184μM. Moreover, it exhibited high sensitivity, acceptable reproducibility and good stability. Besides, the proposed sensor was demonstrated its practicability in real water samples.

Rapid synthesis of ethyl cellulose supported platinum nanoparticles for the non-enzymatic determination of H2O2

Cellulose derivatives are one of the carbohydrate polymers which received a great interest in the construction of nanostructured materials. Particularly, the ethyl cellulose provides an enormous support to the metal nanoparticles. To the best of our knowledge, this is the first time report for the simple and rapid synthesis of ethyl cellulose (EC) supported platinum nanoparticles (PtNPs) for the determination of non-enzymatic hydrogen peroxide (H2O2). The PtNPs/EC composite was confirmed by various characterizations such as fourier transform infra-red spectra, energy dispersive X-ray spectra, field emission scanning electron microscope and cyclic voltammetry. Further, the PtNPs/EC composite modified glassy carbon electrode (GCE) was successfully determined the H2O2 with the linear concentration range from 0.05μM to 2.22mM and the lowest detection limit of 0.01μM. Moreover, the PtNPs/EC/GCE sensor electrode manifested an acceptable sensitivity, selectivity and reproducibility. In addition, we have determined the H2O2 in contact lens solution and human blood serum samples.

Flame synthesis of nitrogen doped carbon for the oxygen reduction reaction and non-enzymatic methyl parathion sensor

Growing concerns about the economical feasibility of materials synthesis means that simple methodologies to furnish materials are needed. Moreover, the multi-functional activity of these as-prepared materials is of great importance. Hence, here we report nitrogen-doped carbon nanoparticles from a one-step flame synthesis by directly burning pyrrole at room temperature and in an air atmosphere. The as-synthesized N-doped carbon was scrutinized as a cathode material for the oxygen reduction reaction and was also demonstrated in an electrochemical sensor. Furthermore, X-ray photoelectron spectroscopy (XPS) and Raman analysis was carried out to confirm the percentage of nitrogen content, the bonding environment and the disorder of carbon. The as-prepared N-doped carbon exhibits superior electrocatalytic activity towards the ORR compared with a commercial Pt/C catalyst. Moreover, the N-doped carbon modified glassy carbon electrode manifests a sensitive electrochemical response towards the detection of methyl parathion. A linear response was demonstrated by the fabricated sensor across two concentration ranges, from 0.0025 to 1 μM and 1 to 100 μM, with a lower detection limit of 0.068 nM. The proposed method is very simple, low cost and it can be utilized for practical applications to produce carbon materials on a large scale.

Sonochemical Synthesis of Sulfur Doped Reduced Graphene Oxide Supported CuS Nanoparticles for the Non-Enzymatic Glucose Sensor Applications

Over the present material synthesis routes, the sonochemical route is highly efficient and comfortable way to produce nanostructured materials. In this way, the copper sulfide (CuS-covellite) and sulfur doped reduced graphene oxide (S-rGO) nanocomposite was prepared by sonochemical method. Interestingly, the structure of the as-prepared S-rGO/CuS was changed from the covellite to digenite phase. Herein, the S-rGO was act as a mild oxidizer and liable for the structural transformations. These structural changes are sequentially studied by various physicochemical characterizations such as Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Transmission electron microscopy (TEM). After scrupulous structural evaluations, the transformation of CuS phase was identified and documented. This oxidized CuS has an excellent electrocatalytic activity when compare to the bulk CuS. This S-rGO/CuS was further used for the determination of glucose and acquired good electrocatalytic performances. This S-rGO/CuS was exhibited a wide linear concentration range, 0.0001–3.88 mM and 3.88–20.17 mM, and a low-level detection limit of 32 nM. Moreover, we have validated the practicability of our developed glucose sensor in real biological samples.