Murugan Velmurugan

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.

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.

Synthesis and Characterization of Porous MnCo 2 O 4 for Electrochemical Determination of Cadmium ions in Water Samples

To utilize the maximum activity of nanomaterials, it was specifically synthesized by appropriate physicochemical properties. In that aspect, we have described the synthesis of porous MnCo2O4 by simple chemical route and applied for the selective detection of cadmium (Cd (II)). The as-prepared porous MnCo2O4 was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) adsorption isotherm, X-ray diffraction pattern analysis (XRD), Fourier transform infra-red spectroscopy (FT-IR), energy dispersive X-ray (EDX) and electrochemical techniques. The porous MnCo2O4 exhibited an excellent electrochemical behaviour and good analytical response towards the determination of Cd (II). Those analytical factors such as pH, deposition potential and deposition time are optimized by using differential pulse anodic stripping voltammetry (DPASV). A wide linear concentration range from 2.3 to 120 µg L−1, limit of detection (LOD) of 0.72 µg L−1 and the limit of quantification (LOQ) of 0.91 µg L−1 were achieved for determination of Cd (II). The selectivity of the developed sensor was explored in the presence of co-interfering ions. Also our sensor exhibits a good stability, reproducibility and repeatability. In addition, the practicability of proposed sensor was evaluated for the detection of Cd (II) in real water samples.

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.

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.

Synthesis and characterizations of biscuit-like copper oxide for the non-enzymatic glucose sensor applications

We described the synthesis of biscuit-like copper oxide (CuO) by the precipitation cum thermal annealing process. The biscuit-like CuO microstructures were successfully obtained by template free synthesis process. Thereby, the oxalic acid was used as the shape forming agent. Herein, the role of the sonic wave was quite important to controlling the shape. The CuO microstructures were characterized by the X-ray diffraction pattern, scanning electron microscope and energy dispersive X-ray analysis. The as-prepared CuO was used to fabricate the disposable sensor electrode using screen printed carbon electrode (SPCE). The CuO modified SPCE was successfully determined the glucose with the linear concentration ranging from 0.0005 to 4.03mM and the lowest detection limit of 0.1μM. The biscuit-like CuO microstructures based glucose sensor displayed appreciable analytical performance than the other CuO nanostructures. Moreover, the disposable CuO/SPCE was applied to determine the glucose in human blood serum, saliva and urine samples. The developed glucose sensor attained good recoveries in real sample analysis, hence, it is applicable for the commercial applications.

Development of electrochemical sensor for the determination of palladium ions (Pd(2+)) using flexible screen printed un-modified carbon electrode.

To date, the development of different modified electrodes have received much attention in electrochemistry. The modified electrodes have some drawbacks such as high cost, difficult to handle and not eco friendly. Hence, we report an electrochemical sensor for the determination of palladium ions (Pd2+) using an un-modified screen printed carbon electrode has been developed for the first time, which are characterized and studied via scanning electron microscope and cyclic voltammetry. Prior to determination of Pd2+ ions, the operational conditions of un-modified SPCE was optimized using cyclic voltammetry and showed excellent electro-analytical behavior towards the determination of Pd2+ ions. Electrochemical determination of Pd2+ ions reveal that the un-modified electrode showed lower detection limit of 1.32μM with a linear ranging from 3 to 133.35μM towards the Pd2+ ions concentration via differential pulse voltammetry. The developed sensor also applied to the successfully determination of trace level Pd2+ ions in spiked water samples. In addition, the advantage of this type of electrode is simple, disposable and cost effective in electrochemical sensors.