Te-Wei Chiu

A non-enzymatic amperometric hydrogen peroxide sensor based on iron nanoparticles decorated reduced graphene oxide nanocomposite

A simple and facile green process was used for the synthesis of iron nanoparticles (FeNPs) decorated reduced graphene oxide (rGO) nanocomposite by using Ipomoea pes-tigridis leaf extract as a reducing and stabilizing agent. The as-prepared rGO/FeNPs nanocomposite was characterized by transmission electron microscopy, X-ray spectroscopy and Fourier transform infrared spectroscopy. The nanocomposite was further modified on the glassy carbon electrode and used for non-enzymatic sensing of hydrogen peroxide (H2O2). Cyclic voltammetry results reveal that rGO/FeNPs nanocomposite has excellent electro-reduction behavior to H2O2 when compared to the response of FeNPs and rGO modified electrodes. Furthermore, the nanocomposite modified electrode shows 9 and 6 folds enhanced reduction current response to H2O2 than that of rGO and FeNPs modified electrodes. Amperometric method was further used to quantify the H2O2 using rGO/FeNPs nanocomposite, and the response was linear over the concentration ranging from 0.1μM to 2.15mM. The detection limit and sensitivity of the sensor were estimated as 0.056μM and 0.2085μAμM-1cm-2, respectively. The fabricated sensor also utilized for detection of H2O2 in the presence of potentially active interfering species, and found high selectivity towards H2O2.

One pot electrochemical synthesis of poly(melamine) entrapped gold nanoparticles composite for sensitive and low level detection of catechol

A simple and cost effective synthesis of nanomaterials with advanced physical and chemical properties have received much attention to the researchers, and is of interest to the researchers from different disciplines. In the present work, we report a simple and one pot electrochemical synthesis of poly(melamine) entrapped gold nanoparticles (PM-AuNPs) composite. The PM-AuNPs composite was prepared by a single step electrochemical method, wherein the AuNPs and PM were simultaneously fabricated on the electrode surface. The as-prepared materials were characterized by various physicochemical methods. The PM-AuNPs composite modified electrode was used as an electrocatalyst for oxidation of catechol (CC) due to its well-defined redox behavior and enhanced electro-oxidation ability towards CC than other modified electrodes. Under optimized conditions, the differential pulse voltammetry (DPV) was used for the determination of CC. The DPV response of CC was linear over the concentration ranging from 0.5 to 175.5μM with a detection limit of 0.011μM. The PM-AuNPs composite modified electrode exhibits the high selectivity in the presence of range of potentially interfering compounds including dihydroxybenzene isomers. The sensor shows excellent practicality in CC containing water samples, which reveals the potential ability of PM-AuNPs composite modified electrode towards the determination of CC in real samples.

Selective Colorimetric Detection of Nitrite in Water using Chitosan Stabilized Gold Nanoparticles Decorated Reduced Graphene oxide

Excess nitrite (NO2-) concentrations in water supplies is considered detrimental to the environment and human health, and is associated with incidence of stomach cancer. In this work, the authors describe a nitrite detection system based on the synthesis of gold nanoparticles (AuNPs) on reduced graphene oxide (rGO) using an aqueous solution of chitosan and succinic acid. The AuNPs-rGO nanocomposite was confirmed by different physicochemical characterization methods including transmission electron microscopy, elemental analysis, X-ray diffraction, UV-visible (UV-vis) and Fourier transform infrared spectroscopy. The AuNPs-rGO nanocomposite was applicable to the sensitive and selective detection of NO2− with increasing concentrations quantifiable by UV–vis spectroscopy and obvious to the naked eye. The color of the AuNPs-rGO nanocomposite changes from wine red to purple with the addition of different concertation of NO2−. Therefore, nitrite ion concentrations can be quantitatively detected using AuNPs-rGO sensor with UV-vis spectroscopy and estimated with the naked eye. The sensor is able to detect NO2− in a linear response ranging from 1 to 20 μM with a detection limit of 0.1 μM by spectrophotometric method. The as-prepared AuNPs-rGO nanocomposite shows appropriate selectivity towards NO2− in the presence of potentially interfering metal anions.

Highly selective electrochemical detection of antipsychotic drug chlorpromazine in drug and human urine samples based on peas-like strontium molybdate as an electrocatalyst

The countless use of antibiotics in veterinary and human medicine causes severe health risks to both humans and animals. In this context, monitoring of the antibiotic drug in the veterinary and human pathological system is important and provokes a universal challenge. Therefore, development of simple and sensitive inorganic materials with unique morphology is of great importance for the trace level monitoring of pharmaceutical content in the environment. Herein, we developed a novel peas-like strontium molybdate catalyst (SrMoO4; SrM) synthesized by a simple sonochemical approach and utilized as an electrochemical sensor for the detection of antipsychotic drug chlorpromazine (CPZ). The crystalline structure, surface morphology, elemental compositions and textural properties were systematically investigated by various analytical and spectroscopic techniques. As an electrochemical sensor, inorganic binary SrM modified screen printed carbon electrode (SrM/SPCE) exhibited an enhanced electrocatalytic activity towards CPZ sensing with excellent analytical performance such as wide linear response ranges and lowest detection limit of 0.1–143 and 153–1683 μM and 0.028 μM respectively. Moreover, the as-prepared SrM/SPCE showed an excellent selectivity even in the existence of co-interfering drugs, biological compounds and common metal ions. In addition, the SrM/SPCE applied to the real samples analysis in commercially available CPZ drug and human urine samples and the observed recoveries are quite satisfactory.

Hexammine cobalt(III) coordination complex grafted reduced graphene oxide composite for sensitive and selective electrochemical determination of morin in fruit samples

In this report, we have successfully prepared the hexammine cobalt(III) coordination complex [Co(NH3)6]3+ grafted onto a reduced graphene oxide (RGO) composite modified glassy carbon electrode (GCE) for the electrochemical determination of morin (MR). The RGO/[Co(NH3)6]3+ composite was prepared by a simple sonochemical technique. The as-prepared inorganic complex was characterized using suitable physical and chemical characterization techniques. The as-prepared composite was characterized by scanning electron microscopy, elemental mapping analysis and X-ray diffraction studies. In addition, the electrochemical performance of the fabricated electrode was assessed by the cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy studies. Besides, the RGO/[Co(NH3)6]3+ modified electrode had notable electrocatalytic activity towards the detection of MR. Under the optimized condition, the modified electrode showed excellent linearity ranges, acceptable limit of detection, and high sensitivity of 0.008–72.35 μM, 1.0 nM and 4.326 μA μM−1 cm−2, respectively. The fabricated electrode exhibited acceptable repeatability, reproducibility and stability. On the other hand, the proposed RGO/[Co(NH3)6]3+ modified electrodes have been applied for the detection of MR in fruit samples, and the results reveal adequate recovery.

Ecofriendly preparation of graphene sheets decorated with an ethylenediamine copper(II) complex composite modified electrode for the selective detection of hydroquinone in water

In the present work, we have prepared an ecofriendly reduced graphene oxide decorated copper(II) ethylenediamine complex ([Cu(en)2]2+) (en = ethylenediamine) modified glassy carbon electrode (GCE) for the electrochemical detection of hydroquinone (HQ). The as-prepared composite was characterized by SEM, EDX, XRD, UV and FT-IR. Moreover, the electrochemical behaviour of the modified electrode was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). In addition, the GCE/RGO/[Cu(en)2]2+ modified electrode has excellent electrocatalytic activity towards the detection of HQ. Under the optimized conditions, the proposed sensor exhibited a wide linear detection response range of 0.1 μM–104 μM with a limit of detection of 0.025 μM and a sensitivity of 5.0763 μA μM−1 cm−2. Furthermore, the fabricated electrode exhibited acceptable reproducibility, repeatability and stability. On the other hand, the GCE/RGO/[Cu(en)2]2+ modified electrodes have been applied for the real sample analysis in environmental water samples, which exhibit acceptable recovery. Hence, it is suggested that the GCE/RGO/[Cu(en)2]2+ modified electrode is a potential electrode material that can be used for the detection of HQ in different real samples.