Designing a proper architecture of supporting electrode materials is the most promising strategy for improving the catalytic activity and chemical stability of electrochemical sensors. Herein, we have successfully synthesized 3D hierarchical flower-like cerium vanadate (CeVO 4 ) nanostructures by a simple hydrothermal approach. A sequence of scanning electron microscopy and spectroscopic techniques is used to clearly confirm the successful construction of CeVO 4 nanostructures. The electrocatalytic activity of these CeVO 4 modified electrodes for the electrochemical detection of clioquinol (CQ) was evaluated by cyclic voltammetry and differential pulse voltammetry methods. Benefiting from its unique 3D flower-like nanostructure, both of charge transfer rate and electronic conductivity were significantly improved, resulting in a significant enhancement in the electrochemical performance along with a wide dynamic linear range 0.02−215 μM, an ultralow detection limit (0.004 μM), a low oxidation peak potential (+0.47 V), and high selectivity in the presence of potentially interfering compounds. Interestingly, the CeVO 4 modified electrode was able to show excellent recovery range for the real sample analysis and could cheer up a commercial sensor, making it a potential sensing option to be applied in marketable electrochemical devices.

Binary metal oxides with carbon nanocomposites have received extensive attention as research hotspots in the electrochemistry field owing to their tunable properties and superior stability. This work illustrates the development of a facile sonochemical strategy for the synthesis of a copper bismuthate/graphene (GR) nanocomposite-modified screen-printed carbon electrode (CBO/GR/SPCE) for the electrochemical detection of catechol (CT). The formation of an as-prepared CBO/GR nanocomposite was comprehensively characterized. The electrochemical behavior of the CBO/GR/SPCE toward CT was investigated by voltammetry and amperometry techniques. The fabricated CBO/GR/SPCE manifests an excellent electrocatalytic performance toward CT with a lower peak potential and a higher current value compared to those of CBO/SPCE, GR/SPCE, and bare SPCE. It is attributed to enhanced electro-catalytic activity, synergetic effects, and good active sites of the CBO/GR nanocomposite. Under the electrochemical condition, the CBO/GR/SPCE displayed a wide linear sensing range, trace-level detection limit, acceptable sensitivity, and excellent selectivity. Furthermore, our proposed CBO/GR electrode was employed successfully for CT detection in water samples.

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The overusage of hydroxychloroquine (HQ) amidst the outbreak of coronavirus disease has contributed to increased fatalities concerning HQ poisoning. Hence, there is an utmost requirement to develop accurate and onsite methodologies for monitoring HQ in biological samples and water bodies. Metal-oxide-decorated carbon nanomaterials present excellent electrocatalytic properties, contributing to improved sensor responses. This study introduces tungsten trioxide nanorods/nitrogen-doped carbon nanofiber (WO3/N-CNF) nanocomposite, capable of detecting HQ electrochemically. The conjunction of WO3 with N-CNF offers accelerated charge transfer kinetics with an abundance of surface-active sites that benefit the sensing mechanism. Furthermore, synergistic effects arising from the nanocomposite augment the conductivity and promote faster ion diffusion. The WO3/N-CNF-based electrochemical sensor deliver high performance in the working concentration range of 0.007–480 μM and provides a detection limit of 2.0 nM for HQ. The fabricated sensor has excellent operational stability and reproducibility and is also able to show a superb selectivity toward HQ in comparison to various interfering compounds. This indicates that the designed WO3/N-CNF nanocomposite can be used as a potential electrocatalyst for the real-time monitoring of HQ.

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An electrocatalyst with a large active site is critical for the development of a high-performance electrochemical sensor. This work demonstrates the fabrication of an iron diselenide (FeSe2)-modified screen-printed carbon electrode (SPCE) for the electrochemical determination of furaltadone (FLD). It has been prepared by the facile method and systematically characterized with various microscopic/spectroscopic approaches. Due to advantageous physiochemical properties, the FeSe2/SPCE showed a low charge-transfer resistance value of 200 Ω in 5.0 mM [Fe­(CN)6]3–/4– containing 0.1 M KCl. More importantly, the FeSe2/SPCE exhibited superior catalytic performance compared to the bare SPCE for FLD sensing based on the electrochemical response in terms of a peak potential of −0.44 V (vs Ag/AgCl (sat. KCl)) and cathodic response current of −22.8 μA. Operating at optimal conditions, the FeSe2-modified electrode showed wide linearity from 0.01 to 252.2 μM with a limit of detection of 0.002 μM and sensitivity of 1.15 μA μM–1 cm–2. The analytical performance of the FeSe2-based platform is significantly higher than many previously reported FLD electrochemical sensors. Furthermore, the FeSe2/SPCE also has a promising platform for FLD detection with high sensitivity, good selectivity, excellent stability, and robust reproducibility. Thus, the finding above shows that the FeSe2/SPCE is a highly suitable candidate for the electrochemical determination of glucose levels for real-time applications such as in human urine and river water samples.

We developed a flexible electrode based on a bismuth molybdate/graphene (BiM/GR) nanocomposite for electrochemical detection of mercury (Hg2+). The formation of the BiM/GR nanocomposite was systematically examined with suitable characterization studies. The BiM/GR-modified electrodes exhibit a high electrocatalytic performance toward Hg2+ detection comparable to other electrodes. The excellent electrocatalytic activity of the BiM/GR nanocomposite can be attributed to its good conductivity, synergistic effect, and abundant active site. Notably, the BiM/GR sensor showed good electrochemical sensing performance for Hg2+ in the wide detection range from 0.02 to 149 μM with a good sensitivity of 9.5 μA μM–1 cm2 and an ultralow detection limit of 5.0 nM, which is well below the threshold value set by the World Health Organization (30 nM) and the United States Environmental Protection Agency. More importantly, the BiM/GR nanocomposite-modified electrode was used successfully to detect Hg2+ in river water, corn, and fish samples with satisfactory recovery values.