Monitoring of toxic organic pollutants in the atmosphere is mandatory. Among them, nitrophenols are considered extensive toxic organic pollutants which cause many adverse effects through their consumption in the biosphere. A highly precise and sensitive electrochemical sensor to detect 4-nitrophenol based on halloysite nanotubes (HNTs) with silver nanoparticles (AgNPs) decorated on reduced graphene oxide (rGO) is reported. The electrochemical performance of the prepared sensor was estimated through cyclic voltammetry and differential pulse voltammetry. The prepared nanomaterial was employed for the efficient detection of 4-nitrophenol. The fabricated sensor exhibited an extensive working range from 0.1 to 363.9 μM under optimized conditions with a lower detection limit of 48.6 nM for 4-nitrophenol (4-NP). The nanocomposite rGO–HNT–AgNP modified electrode showed a high sensitivity of 35.25 μA μM⁻¹ cm⁻², which is much higher than that of the bare electrodes. Furthermore, the evaluation of the developed sensor was done on the basis of practical applicability by determining the presence of 4-NP in real samples obtained from water resources with RSD ± 3.17%.

In this study, the simple sonochemical synthesis of functionalized carbon black (f-CB) anchored with tungsten carbide (WC) is used to prepare a novel electrocatalyst for the electrochemical detection of furazolidone (FU) by modifying screen-printed carbon electrodes (SPCE). X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy were utilized to investigate the crystal structure, surface morphology and elemental composition of the hybrid composite. The results confirmed the successful formation of uniformly distributed flake-like WC on the surface of f-CB. Due to its peculiar and outstanding morphological structure, an f-CB/WC/SPCE electrode has an enriched electroactive surface area of 0.4105 cm². The electrocatalytic efficiency of furazolidone was studied using cyclic voltammetry and amperometric techniques. The f-CB/WC composite displayed an outstanding synergic effect in detecting the ultra-level presence of FU, with a limit of detection of around 0.6 nM and an ultra-dynamic range of 0.001–1150 μM, which outshone other reported FU sensors. Therefore, it is evident that the preparation method can be successfully applied to bovine albumin serum and pharmaceutical tablets with acceptable recovery.

The current study reports a facile simple, low-cost electrochemical sensor in the detection of nitrofurantoin (NFT) by using NiFe/f-MWCNT hybrid composite as a promising electrocatalyst. NFT is an antibiotic drug that is extensively using in pharmaceuticals and also in animal food production which causes a severe threat for both human and animal environments. Extending the residues of NFT are left into rivers, soils, lakes, and groundwaters either found or discharged leading health issues. To this NiFe/f-MWCNT composite was synthesized using a hydrothermal mechanism and then ultrasonicated to form a hybrid composite for catalytic evaluation and electrochemical detection of NFT for the very first time. Furthermore, the physicochemical properties of NiFe nanospheres conjugated on f-MWCNT are scrutinized using various analytical and spectroscopical techniques. Resulting transmission electron microscopy (TEM) displays a chain like NiFe nanospheres anchored on f-MWCNT with a well-defined spherical shape, without any comprehensive agglomeration. The NiFe/f-MWCNT screen printed carbon paste electrode (SPCE) displayed an excellent electrocatalytic activity for NFT with a LOD of 0.03 µM and a sensitivity of 11.45 µA µM⁻¹ cm⁻². establishing a new selectivity and with the existence of co-interfering compounds. To enhance the practical abilities analysis were performed in Human serum and urine samples which resulted in satisfactory recoveries with high precision and linear accuracy illustrated in Scheme 1.