Synergistic Effect of Palm Kernel Shell-Derived Carbon Dots and ZnO Nanorods Towards Enhanced Graphene Electrode for Sensitive Electrochemical Detection

This study presents a sustainable strategy for enhancing electrochemical sensors by developing a hybrid nanocomposite of zinc oxide nanorods (ZnO NRs) and carbon dots (C-dots) synthesized from palm kernel shell biomass via a facile microwave-assisted method. Comprehensive characterization confirmed the successful formation of C-dots@ZnO nano¬composites with an average particle size of 84.0 nm and the presence of functional groups critical for electrocatalytic activity. When employed as a modifier for a graphene-based electrode, the nanocomposite demonstrated exceptional elec¬trochemical performance in the Fe(CN)63−/4− redox system. The optimal formulation (0.03 g C-dots@ZnO NRs / 0.7 g graphene) yielded a significant enhancement, with peak currents of 225.2 μA (Ipa) and − 227.3 μA (Ipc) at a scan rate of 0.020 V/s, and an electroactive surface area of 0.023 cm2, representing a 2.2-fold improvement over the unmodified electrode. The kinetics were governed by a diffusion-controlled process. The enhancement is attributed to the synergistic effect between the conductive C-dots, semiconducting ZnO, and graphene support. This work underscores the potential of biomass-derived nanocomposites for designing efficient, environmentally sustainable platforms for electrochemical sensing applications.