Structural Engineering of Hollow Microflower-like CuS@C Hybrids as Versatile Electrochemical Sensing Platform for Highly Sensitive Hydrogen Peroxide and Hydrazine Detection

Designing metal sulfides with unique configurations and exploring their electrochemical activities for hydrogen peroxide (H₂O₂) and hydrazine (N₂H₄) is challenging and desirable for various fields. Herein, hollow microflower-like CuS@C hybrids were successfully assembled and further exploited as a versatile electrochemical sensing platform for H₂O₂ reduction and N₂H₄ oxidation, of which the elaborate strategies make the perfect formation of hollow architecture, providing considerable electrocatalytic sites and fast charge transfer rate, while the appropriate introduction polydopamine-derived carbon skeleton facilitates the electronic conductivity and boosts structural robustness, thus generating wide linear range (0.05-14 and 0.01-10 mM), low detection limit (0.22 μM and 0.07 μM), and a rather low overpotential (-0.15 and -0.05 V) toward H₂O₂ and N₂H₄, as well as good selectivity, excellent reproducibility, and admirable long-term stability. It should be highlighted that the operating potentials can compare favorably with those of some reported H₂O₂ and N₂H₄ sensors based on noble metals. In addition, good recoveries and acceptable relative standard deviations (RSDs) attained in serum and water samples fully verify the accuracy and anti-interference capability of our proposed sensor systems. These results not only elucidate an effective structural nanoengineering strategy for electroanalytical science but also advance the rational utilization of H₂O₂ and N₂H₄ in practicability.

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.

Ruthenium Nanoparticles Decorated Tungsten Oxide as a Bifunctional Catalyst for Electrocatalytic and Catalytic Applications

The syntheses of highly stable ruthenium nanoparticles supported on tungsten oxides (Ru-WO₃) bifunctional nanocomposites by means of a facial microwave-assisted route are reported. The physicochemical properties of these Ru-WO₃ catalysts with varied Ru contents were characterized by a variety of analytical and spectroscopic methods such as XRD, SEM/TEM, EDX, XPS, N₂ physisorption, TGA, UV-vis, and FT-IR. The Ru-WO₃ nanocomposite catalysts so prepared were utilized for electrocatalytic of hydrazine (N₂H₄) and catalytic oxidation of diphenyl sulfide (DPS). The Ru-WO₃-modified electrodes were found to show extraordinary electrochemical performances for sensitive and selective detection of N₂H₄ with a desirable wide linear range of 0.7-709.2 μM and a detection limit and sensitivity of 0.3625 μM and 4.357 μA μM^-1 cm^-2, respectively, surpassing other modified electrodes. The modified GCEs were also found to have desirable selectivity, stability, and reproducibility as N₂H₄ sensors, even for analyses of real samples. This is ascribed to the well-dispersed metallic Ru NPs on the WO₃ support, as revealed by UV-vis and photoluminescence studies. Moreover, these Ru-WO₃ bifunctional catalysts were also found to exhibit excellent catalytic activities for oxidation of DPS in the presence of H₂O₂ oxidant with desirable sulfoxide yields.

A PLA–TiO2 particle brush as a novel support for CuNPs: a catalyst for the fast sequential reduction and N-arylation of nitroarenes

One pot synthesis of diarylamines from nitro arenes by sequential reduction and N-arylation.

ZrO2 supported Nano-ZSM-5 nanocomposite material for the nanomolar electrochemical detection of metol and bisphenol A

ZrO₂ decorated Nano-ZSM-5 was synthesized by the calcination of the physical mixture of ZrO₂ and Nano-ZSM-5. Electrochemical sensor based on this material was investigated in the determination of hazardous organic water pollutants.

Cu ion-exchanged and Cu nanoparticles decorated mesoporous ZSM-5 catalysts for the activation and utilization of phenylacetylene in a sustainable chemical synthesis

Highly dispersed Cu nanoparticles supported on the large external surface of Meso-ZSM-5 exhibited excellent activity in the selective synthesis of indolizines, chalcones, and triazoles using phenylacetylene as one of the building blocks.