Synthesis of Carbon Quantum Dots from Corn Husk Waste for Enhanced Nonenzymatic Glucose Sensing

Agricultural waste burning contributes significantly to PM2.5 pollution, emphasizing the need for sustainable waste valorization strategies. Here, we report a cost-effective hydrothermal strategy to convert agricultural residues into high-value carbon quantum dots (CQDs). Using NaOH, mixed-structure CQDs down to 5 nm were obtained, while H2SO4 catalysis produced highly crystalline graphene quantum dots (GQDs) as small as 3 nm, both in the presence of a CTAB surfactant. These quantum dots were incorporated into copper oxide nanocomposites via electrodeposition onto screen-printed carbon electrodes to fabricate a nonenzymatic glucose sensor. The resulting sensor exhibited excellent electrochemical performance with a sensitivity of 0.0048 μA·mm–2 ·μM–1 and a detection limit of 6.85 μM. This study highlights the dual benefit of transforming agricultural waste into advanced functional materials while enabling environmentally conscious sensor development, offering a promising pathway for sustainable nanotechnology applications.