Porous tal palm carbon nanosheets were prepared, characterized and utilized for DA and UA sensing.

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A novel electrochemical sensor was fabricated by simply screen printing reduced graphene oxide (rGO) paste on F-doped tin oxide (FTO) (rGO-SP-FTO) followed by sintering at 450 • C in Argon and employed for detecting dopamine (DA) and uric acid (UA) simultaneously. The rGO film was characterized by using Raman spectroscopy, field emission scanning electron microscope (FE-SEM), and Fourier transform infrared spectroscopy (FTIR). The surface sensing features of rGO-SP-FTO were studied with electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The rGO-SP-FTO electrode exhibited foremost sensitivity in simultaneous detection of DA and UA without any interference from ascorbic acid (AA). The rGO-SP-FTO electrode showed a good linear response in the range of 0.5-50.0 μM and 5.0-300 μM with detection limits (S/N = 3) of 0.07 μM and 0.39 μM for DA and UA, respectively. The interactions between screen printed rGO with FTO electrode and their influence on how rGO-SP-FTO electrode interacted with UA, DA, and AA were analyzed from experimental observations. The rGO-SP-FTO electrode was able to detect DA in dopamine hydrochloride injection (DAI) and UA in urine sample effectively. Moreover, the designed electrochemical sensor exhibited excellent stability and reproducibility.

Here, we report the synthesis of a bimetallic supramolecular polymer (SMP) for fabricating an electrochemical nitrite sensor and study the reaction mechanism of the selective oxidation of nitrite by cyclic voltammetry (CV) simulation through the kinetic parameters evaluation. Symmetrical ligand-bearing terpyridine moieties [4′,4⁗-(1,4-Phenylene)­bis­(2,2′:6′,2″-terpyridine)] were complexed with Ni­(II) and Co­(II) salts (Co:Ni:Ligand-0.5:0.5:1) (polyNiCo) to synthesize a heterometallo-SMP. The polyNiCo was characterized by using UV/vis spectrophotometric titration, SEM, EDS, FT-IR, EIS, and CV techniques. The molecular weight of the polymer was determined from the intrinsic viscosity measurement using the Mark–Houwink–Sakurada equation. While the spectroscopic data revealed the structural morphologies and properties of the polyNiCo, electroanalytical characterization studies confirmed the high electrochemical activity and suitability of the polyNiCo heterometallo-SMP as an electrochemical sensor. A glassy carbon electrode (GCE) was used as the base for fabricating ployNiCo_GCE and also for detecting the nitrite analyte through the oxidation process. The kinetics for the irreversible oxidation mechanism were studied using scan-rate and pH-variation methods. The electroactive surface area, electron transfer coefficient, heterogeneous electron transfer rate constant, etc. parameters were studied using the Butler–Volmer equations. We simulated the CV for the nitrite oxidation process at the polyNiCo_GCE based on the analysis of the kinetic parameters obtained from the electroanalytical experiments. An exceptional agreement between the experimental and the simulated CV was found, which confirmed the validity of the calculated kinetic parameters. Using CV and amperometry techniques, we studied the effectiveness of the polyNiCo_GCE for detecting the nitrite analyte at different concentrations. The amperometry technique showed a wide linear range of 2.5 μM–1.73 mM and a limit of detection (LOD) of 0.45 μM. The sensor was also tested for interference, stability, and reproducibility. Real sample analysis was performed using both CV and amperometry techniques, and the obtained results were compared with the results obtained by using standard solutions.

In this study, the cost of working electrode was reduced greatly by replacing glassy carbon electrode (GCE) with 2B pencil. The pencil lead was modified with carbon nanotubes (CNTs) for simultaneous and quantitative detection of hydroquinone (HQ) and catechol (CT). The surface morphology of CNT-modified pencil electrode (PE-CNT) was studied by scanning electron microscopy (SEM) whereas electron transfer properties were evaluated through electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). This electrode evinced an enhanced redox reversibility and superior electrocatalytic performance concerning HQ and CT. Consecutive concentration variation studies exhibited linearity in oxidation peak responses up to 300 μM for each of the analytes with a detection limit (S/N = 3) as low as 1.5 and 0.7 μM for HQ and CT, respectively. We proposed a possible mechanism for their sensitive detection. The developed sensor was successfully examined for real sample analysis with tap water and it exhibited a stable and reliable recovery data with high reproducibility. The cost of the 2B pencil is 1000 times lower than that of GCE. Thus, the 2B pencil can be a good alternative to GCE in electrochemical sensor fabrication due to its economic advantage.