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Scheme I:
Schematic of the electrochemical sensor fabrication with the real image of the sensor.
Figure 1:
(a) SEM image of bare LIG (b) modified with MB (c) EDX analysis. EDX, energy dispersive X-ray; LIG, laser-induced graphene; MB, methylene blue; SEM, scanning electron microscopy.
Figure 2:
(a) XRD of the LIG/MB (b) XPS of the LIG/MB modification. LIG, laser-induced graphene; MB, methylene blue; XRD, X-ray diffraction; XPS, X-ray photoelectron scattering.
Figure 3:
(a) EIS of bare LIG and LIG/MB, (b) Comparative CV response of LIG and LIG/MB with the potassium ferricyanide–KCl solution for 50 mV/S, n = 4 (number of cycle). CV, cyclic voltammetry; EIS, electrochemical impedance spectroscopy; LIG, laser-induced graphene; MB, methylene blue.
Figure 4:
(a) Comparative CV of bare LIG in pH7 PBS and 1 mM Na2S at 10 mV/S for n = 4, (b) Comparative CV of LIG/MB in (pH = 7) PBS and 1 mM Na2S at 10 mV/S for n = 4. CV, cyclic voltammetry; LIG, laser-induced graphene; MB, methylene blue; PBS, phosphate buffer solution.
Figure 5:
(a) Scan rate of 0.1 M PBS (pH = 7.4) on LIG/MB electrochemical sensor, (b) Scan rate test of 1 mM Na2S on LIG/MB electrochemical sensor, (c) Scan rate calibration curve (Ipa vs. sqrt(ν)) (d) Laviron plot of the LIG/MB electrochemical sensor from the scan rate plot. LIG, laser-induced graphene; MB, methylene blue; PBS, phosphate buffer solution.
Figure 6:
(a) Concentration analysis on LIG/MB–based electrochemical sensor (b) calibration curve of the concentration analysis Ipa vs. concentration. Two linear ranges can be observed. LIG, laser-induced graphene; MB, methylene blue.
Figure 7
(a) pH analysis of PBS on the LIG/MB electrochemical sensor ranging from 3 to 11 pH (b) Ipa vs. pH (c) Epa vs. pH. LIG, laser-induced graphene; MB, methylene blue; PBS, phosphate buffer solution.
Figure 8:
Interference effect analysis (a) with the direct interfering analyte (b) with the gases.
Figure 9:
(a) Repeatability and (b) reproducibility of the fabricated electrochemical.
Figure 10:
Real Sample analysis of (a) Kapra Lake, (b) Hussain Sagar Lake, (c) Shameerpet Lake.