Nitrogen-doped Graphene Electrochemical Sensor for Selenium (IV) in Water

Abstract

In this study, the electrochemical detection of Se(IV) on a glassy carbon electrode (GCE) modified with nitrogen-doped graphene (NG) is reported. NG was synthesized from graphene oxide (GO) by thermal annealing of GO in ammonia. Structural and morphological studies of the synthesized NG were conducted using field emission scanning electron microscopy (FESEM), Raman spectroscopy, high resolution-transmission electron microscopy (HR-TEM), Fourier Transform -infrared spectroscopy (FT-IR) and a CHNS analyzer. Electrochemical characterization of the unmodified GCE and the NG modified GCE (GCE-NG) was conducted using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The newly developed GCE-NG sensor demonstrated improved electrochemical properties when compared to the bare GCE. Square wave anodic stripping voltammetry (SWASV) was employed to optimize the proposed sensors' detection parameters: 0.1 M HClO4 supporting electrolyte, -0.8 V deposition potential and 50 s deposition. The calibration graph of Se(IV) concentrations and current response demonstrated linearity during the calibration of the sensor in the concentration range 1 -120 ppb, with a limit of detection (LOD) of 0.092 ppb. The proposed electrochemical sensor was applied in the analysis of real water samples and inductively coupled plasmaoptical emission spectroscopy (ICP-OES) was used to validate the results.

Flexible Polyester Screen‐printed Electrode Modified with Carbon Nanofibers for the Electrochemical Aptasensing of Cadmium (II)

“…This information corroborated the high oxygen content observed in the oxidized CNFs obtained in the CHNS elemental study. Other notable peaks were C=O (1583 cm −1 ), C=C (1645 cm −1 ), CO 2 (2370 cm −1 ), and CH (2854 and 2925 cm −1 ) [11].…”

“…These confirm reversible and diffusion controlled electron processes on the ferri/ferrocyanide and CNFsÀ SPE interface. The electroactive surface area of CNFsÀ SPE was estimated using the Randles-Sevcik equation: I pa = 2.69 × 10 5 n 3/ 2 A eff D 1/2 υ 1/2 C 0 [11] and the slope of I pa vs υ 1/2 and was found to be 0.092 cm 2 (larger than the electroeffective area of the bare SPE at 0.039 cm 2 ), and thus explains the reduced ΔE of the CNFsÀ SPE obtained using CV.…”

“…However, the proximity in deposition potentials/stripping potentials among some metals and the inhibition of signals by hydrogen evolution reactions are challenges that cannot be ignored in anodic stripping voltammetry. [10][11][12][13]. To overcome these drawbacks, biorecognition elements are incorporated into the electrochemical sensors to improve specificity.…”

Electrochemical Detection of Arsenite Using a Silica Nanoparticles-Modified Screen-Printed Carbon Electrode

“…The dependence of the anodic peak current concerning the applied deposition potential was analyzed from −1.0 to −0.2 V. As can be seen in Figure 6 c, the intense stripping peak current appeared at −0.5 V during the detection of As(III). From the observation, the peak current increased significantly in the range of −0.1 to −0.5 V. However, as the deposition potential becomes more negative, the peak current leveled off due to the increasingly competitive H 2 production which brought about the hydrogen evolution reaction occurring at the electrode surface at a more negative potential, which resulted in decreasing the current signals [ 37 ]. Hence, −0.5 V was adopted as the optimal deposition potential.…”

Detection of Selenium and Nickel Metal Ion in Water Using Mn3O4-Cn-Modified Electrode

“…where R is the correlation coefficient and ʋ is the scan rate [21,22]. Evidently, peak currents of Mn 3 O 4 -Cn electrode are higher than Mn 3 O 4 , due to more active surface area and, hence, increased conductivity after adding Cn [21].…”