Pencil Graphite Electrodes Enhanced with Green Synthesized Nano Particles as Efficient Electrocatalysts for Application in Bio-Fuel Cells

Over the past decade, the integration of nanomaterials into electrode surfaces has gained significant attention due to their unique properties and enhanced performance in various applications. Copper and silver nanoparticles prepared through green synthesis using plant extracts have shown great potential in enzymatic biofuel cells when coated with pencil graphite electrodes (PGEs). This work investigates the performance of cost-effective, green-synthesized copper and silver nanomaterials (from Rosa centifolia) when integrated with pencil graphite electrodes. A suitable grade pencil lead is coated with the obtained copper and silver nanoparticles to obtain modified electrodes. Electrochemical and morphological characterizations are carried out using cyclic voltammetry (CV), Electrochemical impedance spectroscopy (EIS), open circuit potential (OCP), scanning electron microscope (SEM), X-ray diffraction spectrophotometry (XRD), and nuclear magnetic resonance spectroscopy (NMR). In a half-cell electrode assembly, AgNP/ PGE (silver nanoparticles coated electrode) anode with 2B grade resulted in a higher current density of 2450 μA cm⁻², followed by a CuNP/ PGE (copper nanoparticles coated electrode) anode with 2B grade with a current density of 1090 μA cm⁻² when compared to bare PGE with 2B grade with a current density 764 μA cm⁻². EIS measurements showed lower R_ct values for AgNP/PGE (0.7 mm) 2B (930 Ω) and CuNP/PGE (0.7 mm) 2B (1529.1 Ω) compared to bare/PGE (0.7 mm) 2B (3755.7 Ω). The EIS data indicates improved electron transfer through the redox couple due to Ag and Cu nanoparticles on the electrode surface. Therefore, 2B grade AgNP/PGE exhibits better electron transfer kinetics with improved surface area, resulting in high-performing electrodes, providing scope for future renewable energy production.