An Enzymatic Biosensor Based on MgO Nanoparticles Grafted on Reduced Graphene Oxide Nanoflakes for the Ultrasensitive Detection of Phenolic Compounds from Wastewater

Abstract In the present work, an enzymatic biosensor has been fabricated using reduced graphene‐magnesium oxide nanoflakes (rGO‐MgONf). For the fabrication of the bioelectrode, the synthesized rGO‐MgONf were electrophoretically deposited onto indium tin oxide (ITO) coated glass substrate, followed by the covalent immobilization of the Laccase (lac) enzyme. Electrochemical studies show an enhanced diffusion coefficient (10.29×10 −12 cm 2 s −1 ), and exchange current per geometric unit area (3.66 μA cm −2 ) on using the rGO‐MgONf/ITO electrode compared to the GO/ITO and MgO/ITO electrode. Further, the fabricated biosensor (lac/rGO‐MgONf/ITO) displayed excellent performance towards hydroquinone (Hq) detection, with a low limit of detection (0.15 μM), wide linear range (1.0–100.0 μM), and high sensitivity (10.0 μA μM −1 cm −2 ). The selectivity study suggests that the fabricated biosensor efficiently detects Hq in wastewater. Additionally, the fabricated biosensor shows good stability and reproducibility for detecting Hq in tap and river water with an excellent recovery rate.