Novel nonenzymatic hydrogen peroxide sensor based on Fe3O4/PPy/Ag nanocomposites

Hydrogen Peroxide Electrochemical Sensor Based on Ag/Cu Bimetallic Nanoparticles Modified on Polypyrrole

Due to the strong oxidizing properties of H2O2, excessive discharge of H2O2 will cause great harm to the environment. Moreover, H2O2 is also an energetic material used as fuel, with specific attention given to its safety. Therefore, it is of great importance to explore and prepare good sensitive materials for the detection of H2O2 with a low detection limit and high selectivity. In this work, a kind of hydrogen peroxide electrochemical sensor has been fabricated. That is, polypyrrole (PPy) has been electropolymerized on the glass carbon electrode (GCE), and then Ag and Cu nanoparticles are modified together on the surface of polypyrrole by electrodeposition. SEM analysis shows that Cu and Ag nanoparticles are uniformly deposited on the surface of PPy. Electrochemical characterization results display that the sensor has a good response to H2O2 with two linear intervals. The first linear range is 0.1-1 mM (R2 = 0.9978, S = 265.06 μA/ (mM × cm2)), and the detection limit is 0.027 μM (S/N = 3). The second linear range is 1-35 mM (R2 = 0.9969, 445.78 μA/ (mM × cm2)), corresponding to 0.063 μM of detection limit (S/N = 3). The sensor reveals good reproducibility (σ = 2.104), repeatability (σ = 2.027), anti-interference, and stability. The recoveries of the electrode are 99.84-103.00% (for 0.1-1 mM of linear range) and 98.65-104.80% (for 1-35 mM linear range). Furthermore, the costs of the hydrogen peroxide electrochemical sensor proposed in this work are reduced largely by using non-precious metals without degradation of the sensing performance of H2O2. This study provides a facile way to develop nanocomposite electrochemical sensors.

Novel Electrochemical Sensors Based on L-Proline Assisted LDH for H2O2 Determination in Healthy and Diabetic Urine

In this paper, a novel non-enzymatic modified glassy carbon (GC) sensor, of the (GC-Ag_paste)-catalytic proline-assisted LDH type, for H₂O₂ determination was fabricated, studied, characterized and employed to determine the hydrogen peroxide content in healthy and diabetic human urine. LDH (whose composition can be schematized as [Zn^IIAl^III (OH)₂]⁺ NO₃^-·nH₂O) is glued to glassy carbon by means of silver paste, while proline, which increases the catalytic properties of LDH, is used free in solution in the phosphate buffer. A voltametric survey was first conducted to ascertain the positive effect induced by the presence of proline, i.e., the increase of sensor sensitivity. Then a deep study of the new three-electrode amperometric proline-assisted LDH sensor, whose working electrode was of the same type as the one used to perform the cyclic voltammetry, was carried out, working at first in static air, then in a nitrogen atmosphere. Possible interferences from various substances, both oxidants and antioxidants, were also investigated. Lastly, the new amperometric sensor was successfully used to determine the H₂O₂ level in human urine from both healthy and diabetic subjects. The effect of proline in enhancing the properties of the sensor system was also investigated. The limit of detection (LOD) of the new catalytic sensor was of the order of 0.15 mmol L^-1, working in air, and of 0.05 µmol L^-1, working in nitrogen atmosphere.

A facile construction of Ag/MoSe2 composite based non-enzymatic amperometric sensor for hydrogen peroxide

We report an electrochemical non-enzymatic method for hydrogen peroxide (H2O2) detection based on Ag nanoparticle-decorated MoSe2 (Ag/MoSe2-500) hybrid nanostructures. These hybrid nanocomposites are easily prepared by in-situ reduction of Ag+...

Novel Enzyme-Free Multifunctional Bentonite/Polypyrrole/Silver Nanocomposite Sensor for Hydrogen Peroxide Detection over a Wide pH Range

Precise designs of low-cost and efficient catalysts for the detection of hydrogen peroxide (H₂O₂) over wide ranges of pH are important in various environmental applications. Herein, a versatile and ecofriendly approach is presented for the rational design of ternary bentonite-silylpropyl-polypyrrole/silver nanoarchitectures (denoted as BP-PS-PPy/Ag) via the in-situ photo polymerization of pyrrole with salinized bentonite (BP-PS) in the presence of silver nitrate. The Pyrrolyl-functionalized silane (PS) is used as a coupling agent for tailoring the formation of highly exfoliated BP-PS-PPy sheet-like nanostructures ornamented with monodispersed Ag nanoparticles (NPs). Taking advantage of the combination between the unique physicochemical properties of BP-PS-PPy and the outstanding catalytic merits of Ag nanoparticles (NPs), the as-synthesized BP-PS-PPy/Ag shows a superior electrocatalytic reduction and high-detection activity towards H₂O₂ under different pH conditions (from 3 to 10). Intriguingly, the UV-light irradiation significantly enhances the electroreduction activity of H₂O₂ substantially, compared with the dark conditions, due to the high photoelectric response properties of Ag NPs. Moreover, BP-PS-PPy/Ag achived a quick current response with a detection limit at 1 μM within only 1 s. Our present approach is green, facile, scalable and renewable.

Detection of pH and Enzyme-Free H2O2 Sensing Mechanism by Using GdO x Membrane in Electrolyte-Insulator-Semiconductor Structure

A 15-nm-thick GdO x membrane in an electrolyte-insulator-semiconductor (EIS) structure shows a higher pH sensitivity of 54.2 mV/pH and enzyme-free hydrogen peroxide (H2O2) detection than those of the bare SiO2 and 3-nm-thick GdO x membranes for the first time. Polycrystalline grain and higher Gd content of the thicker GdO x films are confirmed by transmission electron microscopy (TEM) and X-ray photo-electron spectroscopy (XPS), respectively. In a thicker GdO x membrane, polycrystalline grain has lower energy gap and Gd(2+) oxidation states lead to change Gd(3+) states in the presence of H2O2, which are confirmed by electron energy loss spectroscopy (EELS). The oxidation/reduction (redox) properties of thicker GdO x membrane with higher Gd content are responsible for detecting H2O2 whereas both bare SiO2 and thinner GdO x membranes do not show sensing. A low detection limit of 1 μM is obtained due to strong catalytic activity of Gd. The reference voltage shift increases with increase of the H2O2 concentration from 1 to 200 μM owing to more generation of Gd(3+) ions, and the H2O2 sensing mechanism has been explained as well.