One-step potentiostatic electrodeposition of NiS-NiS₂ on sludge-based biochar and its application for a non-enzymatic glucose sensor

Conventional nanomaterials are available in electrochemical glucose nonenzymatic sensing, but their broad applications are limited due to their high cost and complicated preparation procedures. In this study, NiS-NiS2/sludge-based biochar/GCE was fabricated by one-step potentiostatic electrodeposition on biochar and used as an interface material for non-enzymatic sensing of glucose in 0.1 M NaOH. With an electrodeposition time of 300 s, the as-prepared sensors delivered the best electrochemical performance toward glucose due to the synergistic effects of NiS-NiS2 and sludge-based biochar. The as prepared NiS-NiS2/sludge-based biochar surface morphology, surface composition, and electrochemical properties were characterized by SEM elemental mapping, XPS and cyclic voltammetry. Under optimized conditions, the linearity between the current response and the glucose concentration has been obtained in the range of 5-1500 mu M with a detection limit of 1.5 mu M. More importantly, the fabricated sensor was successfully utilized to measure glucose in serum of sweetened beverages and human blood. Accordingly, NiS-NiS2/sludge-based biochar/GCE can hopefully be applied as a normal enzyme-free glucose sensor with excellent properties of sensitivity, reproducibility, stability, as well as sustainability.