Hydroquinone is a widely used derivative of phenol which has a negative influence on human beings and the environment. The determination of the accurate amount of hydroquinone is of great importance. Recently, the fabrication of an electrochemical sensing device has received enormous attention. In this study, we reported on the facile synthesis of cerium dioxide (CeO₂) nanoparticles (NPs). The CeO₂ NPs were synthesized using cerium nitrate hexahydrate as a precursor. For determining the physicochemical properties of synthesized CeO₂ NPs, various advanced techniques, viz., powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS), were studied. Further, these synthesized CeO₂ NPs were used for the modification of a glassy carbon electrode (CeO₂/GCE), which was utilized for the sensing of hydroquinone (HQ). A decent detection limit of 0.9 µM with a sensitivity of 0.41 µA/µM cm² was exhibited by the modified electrode (CeO₂/GCE). The CeO₂/GCE also exhibited good stability, selectivity, and repeatability towards the determination of HQ.

In the past few years, the design and fabrication of highly sensitive and selective electrochemical sensors have received enormous attention from electrochemists. Acetaminophen is an important drug that is used as an antipyretic and analgesic drug throughout the world. It is important to monitor the accurate amount of acetaminophen. Herein, we have prepared sulfur-doped reduced graphene oxide (S@rGO) using simple strategies. The morphological feature of the S@rGO was characterized by using scanning electron microscopy whereas phase purity and formation of S@rGO were authenticated by X-ray diffraction. Further, the glassy carbon electrode was modified using S@rGO as an electrode modifier and employed as an acetaminophen sensor (S@rGO/GCE). This modified sensor (S@rGO/GCE) demonstrates a reasonable detection limit of 0.07 µM and a sensitivity of 0.957 µA/µMcm².

Recently, the electrochemical sensing approach has attracted materials/electrochemical scientists to design and develop electrode materials for the construction of electrochemical sensors for the detection of para-nitrophenol (4-NP). In the present study, we have prepared a hybrid composite of MnO₂ and rGO (MnO₂/rGO) using a hydrothermal approach. The morphological features of the prepared MnO₂/rGO composite were studied by scanning electron microscopy, whereas the phase purity and formation of the MnO₂/rGO composite were authenticated via the powder X-ray diffraction method. Energy-dispersive X-ray spectroscopy was also employed to analyze the elemental composition of the prepared MnO₂/rGO composite. In further studies, a glassy carbon electrode (GCE) was modified with MnO₂/rGO composite (MnO₂/rGO/GCE) and explored as 4-nitrophenol (4-NP) sensor. The fabricated MnO₂/rGO/GCE exhibited a reasonably good limit of detection of 0.09 µM with a sensitivity of 0.657 µA/µMcm². The MnO₂/rGO/GCE also demonstrates good selectivity, stability and repeatability in 50 cycles.

Serotonin is a very important monoamine neurotransmitter, which takes part in biological and psychological processes. In the present scenario, design and fabrication of a serotonin electrochemical sensor is of great significance. In this study, we have synthesized α-MnO₂ via a hydrothermal synthesis method using potassium permanganate as a precursor. The physiochemical properties, such as structural and phase-purity of the prepared α-MnO₂, were investigated by various characterization techniques and methods (powder X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy). Furthermore, the serotonin sensor was fabricated using α-MnO₂ as an electrode modifier or electro-catalyst. The bare glassy carbon electrode (GCE) was adopted as a working substrate, and its active carbon surface was modified with the synthesized α-MnO₂. This modified GCE (α-MnO₂/GCE = MGCE) was explored as a serotonin sensor. The electrochemical investigations showed that the MGCE has excellent electro-catalytic properties towards determination of serotonin. The MGCE exhibits an excellent detection limit (DL) of 0.14 µM, along with good sensitivity of 2.41 µAµM⁻¹ cm⁻². The MGCE also demonstrated excellent selectivity for determination of serotonin in the presence of various electro-active/interfering molecules. The MGCE also exhibits good cyclic repeatability, stability, and storage stability.