A nanomaterial composed of cobalt nanoparticles, poly(3,4-ethylenedioxythiophene) and graphene with high electrocatalytic activity for nitrite oxidation

Recent Developments in Polymer Nanocomposite-Based Electrochemical Sensors for Detecting Environmental Pollutants

The human population is generally subjected to diverse pollutants and contaminants in the environment like those in the air, soil, foodstuffs, and drinking water. Therefore, the development of novel purification techniques and efficient detection devices for pollutants is an important challenge. To date, experts in the field have designed distinctive analytical procedures for the detection of pollutants including gas chromatography/mass spectrometry and atomic absorption spectroscopy. While the mentioned procedures enjoy high sensitivity, they suffer from being laborious, expensive, require advanced skills for operation, and are inconvenient to deploy as a result of their massive size. Therefore, in response to the above-mentioned limitations, electrochemical sensors are being developed that enjoy robustness, selectivity, sensitivity, and real-time measurements. Considerable advancements in nanomaterials-based electrochemical sensor platforms have helped to generate new technologies to ensure environmental and human safety. Recently, investigators have expanded considerable effort to utilize polymer nanocomposites for building the electrochemical sensors in view of their promising features such as very good electrocatalytic activities, higher electrical conductivity, and effective surface area in comparison to the traditional polymers. Herein, the first section of this review briefly discusses the most important methods for polymer nanocomposites synthesis, such as in situ polymerization, direct mixing of polymer and nanofillers (melt-mixing and solution-mixing), sol-gel, and electrochemical methods. It then summarizes the current utilization of polymer nanocomposites for the preparation of electrochemical sensors as a novel approach for monitoring and detecting environmental pollutants which include heavy metal ions, pesticides, phenolic compounds, nitroaromatic compounds, nitrite, and hydrazine in different mediums. Finally, the current challenges and future directions for the polymer nanocomposites-based electrochemical sensing of environmental pollutants are outlined.

Application of Graphene-Based Materials for Detection of Nitrate and Nitrite in Water-A Review

Nitrite and nitrate are widely found in various water environments but the potential toxicity of nitrite and nitrate poses a great threat to human health. Recently, many methods have been developed to detect nitrate and nitrite in water. One of them is to use graphene-based materials. Graphene is a two-dimensional carbon nano-material with sp² hybrid orbital, which has a large surface area and excellent conductivity and electron transfer ability. It is widely used for modifying electrodes for electrochemical sensors. Graphene based electrochemical sensors have the advantages of being low cost, effective and efficient for nitrite and nitrate detection. This paper reviews the application of graphene-based nanomaterials for electrochemical detection of nitrate and nitrite in water. The properties and advantages of the electrodes were modified by graphene, graphene oxide and reduced graphene oxide nanocomposite in the development of nitrite sensors are discussed in detail. Based on the review, the paper summarizes the working conditions and performance of different sensors, including working potential, pH, detection range, detection limit, sensitivity, reproducibility, repeatability and long-term stability. Furthermore, the challenges and suggestions for future research on the application of graphene-based nanocomposite electrochemical sensors for nitrite detection are also highlighted.

Printed Combinatorial Sensors for Simultaneous Detection of Ascorbic Acid, Uric Acid, Dopamine, and Nitrite

In this study, an effective and simple direct printing method was developed to create sensing devices on screen-printed carbon electrodes (SPCEs) to detect multiple species simultaneously. Two sensing materials, graphene oxide nanoribbons (GONRs) and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), were printed on one SPCE for detection of multiple biochemical substances. Printed layers of the GONRs and PEDOT:PSS mixture (GONRs & PEDOT:PSS) on SPCE showed embedment of GONRs in the PEDOT:PSS layer and diminished the electrochemical activity of GONRs. In contrast, by printing the GONRs and PEDOT:PSS at separate locations (GONRs + PEDOT:PSS) on the same SPCE, the electrochemical activities of both GONRs and PEDOT:PSS can be preserved. Thus, without synthesizing new materials, the modified electrode is able to simultaneously detect ascorbic acid (AA), uric acid (UA), dopamine (DA), and nitrite (NO₂^-), with high anodic oxidation currents and well-separated voltammetric peaks, in differential pulse voltammetry measurements. The detection limits for the four analytes are 41 nM (AA), 30 nM (DA), 11 nM (UA), and 18 nM (NO₂^-), respectively. The electrode can either detect single species separately or simultaneously determine specific concentrations of the four species in aqueous mixtures, and this can be further extended for many other electrochemical sensing applications.

Electrochemical detection of nitrite based on glassy carbon electrode modified with gold–polyaniline–graphene nanocomposites

This study reports possible interferences for the detection of NO₂⁻ on a Au–G–PANI/GCE.

Polythiophenes and polythiophene-based composites in amperometric sensing

This overview of polythiophene-based materials provides a critical examination of meaningful examples of applications of similar electrode materials in electroanalysis. The advantages arising from the use of polythiophene derivatives in such an applicative context is discussed by considering the organic conductive material as such, and as one of the components of hybrid materials. The rationale at the basis of the combination of two or even more individual components into a hybrid material is discussed with reference to the active electrode processes and the consequent possible improvements of the electroanalytical performance. In this respect, study cases are presented considering different analytes chosen among those that are most frequently reported within the classes of organics and inorganics. The use of a polythiophene matrix to stably fix biological elements at the electrode surface for the development of catalytic biosensors and genosensors is also discussed. Finally, a few possible lines along which the next research in the field could be fruitfully pursued are outlined. Furthermore, the work still to be done to exploit the possibilities offered by novel products of organic synthesis, even along paths already traced in other fields of electrochemistry, is discussed.