Two-dimensional VSe2 nanoflakes as a promising sensing electrocatalyst for nitrobenzene determination in water samples

Vanadium diselenide (VSe2) is an unprecedented transition metal dichalcogenide (TMD) with unusual characteristics in low dimensionality. Although theoretical studies suggest promising sensing features, its sensing applicability is yet unexplored. Herein, we propose the implementation of two-dimensional (2D) VSe2 nanoflakes for the voltammetric determination of nitrobenzene (NB); a highly toxic and hazardous compound that contaminates water sources due to increased industrial activity. Few-nanometers-thick VSe2 flakes were obtained through a simple and facile ultrasonication process followed by a centrifugation-based size selection step. Structural and morphological insights into the exfoliated material were obtained through various characterization techniques, including XRD, Raman, TGA, SEM-EDS, AFM, and XPS. The 2D-VSe2 modified glassy carbon electrode (VSe2/GCE) exhibits excellent electrocatalytic activity towards NB reduction, with a three-fold higher response compared to the unmodified electrode. The mechanism underlying the NB electrochemical reduction on the VSe2/GCE interface and the optimal sensing conditions are explored by voltammetric measurements. Under selected conditions, VSe2/GCE displays a linear relationship with the concentration of NB (R2=0.9993) over the range of 0.1-4 μM, with a limit of detection (S/N 3) as low as 0.03 μM. The sensor was successfully applied for the determination of nitrobenzene in untreated spiked water samples, with the recovery ranging from 93-96%.