Electrochemical and sensing properties of 2D-MoS2 nanosheets produced via liquid cascade centrifugation

In this paper, layered molybdenum disulfide (2D-MoS2) nanosheets of different size and number of layers were prepared via liquid cascade centrifugation (LCC) and their microstructural, morphological and electrochemical characteristics for the detection of dopamine (DA) and riboflavin (RF) were investigated. The microstructural and morphological characteristics of 2D-MoS2 nanosheets obtained at different centrifugation rates were eval-uated by UV-Vis, Raman spectroscopy, and SEM analysis. The 2D-MoS2 nanosheets obtained showed a monotonic decrease of average lateral sheet size < L > and number of layers < N > with the increase of the centrifugation speed. Screen printed carbon electrodes (SPCE) were modified by drop casting on their surfaces 2D-MoS2 nanosheets from aqueous dispersions. The electrochemical properties of the modified 2D-MoS2/SPCE were assessed by electrical impedance spectroscopy and cyclic voltammetry in [Fe (CN)6]3-/4-redox probe. DA and RF were tested to investigate the role of < N > and < L > of MoS2 nanosheets in the electrochemical sensing of these two biomolecules. Results have shown no significant variations in the electrochemical parameters for DA sensing using the different modified electrodes. In contrast, the electro-oxidation of RF was found to be largely promoted on the 2D-MoS2-based electrode with smaller lateral size and minor number of layers, demonstrating the feasibility of tuning the electrochemical properties of 2D-MoS2 nanosheets by modifying their geometric features. The study proposes LCC as an alternative promising technique for preparing nanomaterials with enhanced performances for developing electrochemical sensors for biomolecules.