Development of MWCNT/Gd2O3/SnO2 composite fabricated GCE for voltammetric detection of L- cysteine

A highly sensitive electrochemical method for the determination of L- Cysteine (L-cys) was developed using a glassy carbon electrode (GCE) modified with the composite of bimetallic gadolinium oxide (Gd2O3) and stannous oxide (SnO2) embedded on multi-walled carbon nanotubes (MWCNT). This modified electrode shows excellent electrocatalytic activity toward the oxidation of L-cys in a phosphate buffer solution (0.1 M, pH 7). The proposed electrode showed a linear range of 0.011 μM–27.7 μM, sensitivity of 0.048 μA μM−1 cm−2 and a detection limit (LOD) of 5.993 nM. X-Ray diffraction analysis (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), and Energy-Dispersive X-ray Analysis (EDAX) was performed to characterize all the synthesized materials and the composite prior to electrode fabrication. Linear sweep voltammetry (LSV) was performed to account for the rise in the anodic peak in the potential concluding the current conductivity. Differential pulse voltammetry (DPV) was also performed to confirm the results. This work introduces a simple and easy approach to the sensitive detection of L-cys. Electrochemical impedance spectroscopy (EIS) and Cyclic voltammetry (CV) was employed to characterize the fabricated electrode and was used to investigate the redox properties of this modified electrode at various scan rates. This low-cost nanomaterial fabricated has a wide linear range with excellent stability and reproducibility. The practical applicability of the sensor was confirmed by sensing the L-cys in real samples, possessing satisfactory recoveries (95.8 % and 107.1 %).