A sensitive non-enzymatic glucose sensor based on MgO entangled nanosheets decorated with CdS nanoparticles: Experimental and DFT study

Abstract

MgO entangled nanosheets (MgOENS) with unique vertically-oriented morphology were produced via anodization and functionalized with CdS nanoparticles (NPs). Structural and morphological analyses confirmed the successful functionalization of CdS NPs on the surface of MgOENS. The pristine (MgOENS) and hybrid (CdS@MgO) nanostructures were employed as a non-enzymatic glucose sensor. The MgOENS showed a sensitivity of -12363 lA cm-2 mM-1, fast response time of 4 s, detection limit of 0.5 lM and linear range of detection was 0.0025 mM to 0.035 mM, respectively. The hybrid electrode exhibited the highest sensitivity of -28,570 lA cm-2 mM-1 with a low detection limit (0.020 lM), wide linear range of 1.25 lM to 15 mM and fast response time (2 s) toward glucose compared to the pristine electrode. This is attributed to the lower band gap energy of the electrode material, formation of heterojunction points, and creation of additional active surface sites due to CdS NPs decoration which enhanced the electron transfer rate. Density functional theory simulations confirmed that MgOENS can greatly enhance the sensing behavior toward glucose due to the negative adsorption energy (-1.67 eV) and larger reduction in energy gap (0.599 eV). The real-time analysis of glucose in human blood serum reflects the high accuracy of the fabricated electrode. The proposed biosensor showed ultra-high sensitivity and excellent selectivity making MgOENS decorated with CdS NPs can be potential active material for biosensing. (c) 2022 Elsevier B.V. All rights reserved.