Preparation of Close-Packed Silver Nanoparticles on Graphene to Improve the Enzyme Immobilization and Electron Transfer at Electrode in Glucose/O₂ Biofuel Cell

In this study, chemical reduced graphene-silver nanoparticles hybrid (AgNPs@CR-GO) with close-packed AgNPs structure was used as a conductive matrix to adsorb enzyme and facilitate the electron transfer between immobilized enzyme and electrode. A facile route to prepare AgNPs@CR-GO was designed involving in β-cyclodextrin (β-CD) as reducing and stabilizing agent. The morphologies of AgNPs were regulated and controlled by various experimental factors. To fabricate the bioelectrode, AgNPs@CR-GO was modified on glassy carbon electrode followed by immobilization of glucose oxidase (GOx) or laccase. It was demonstrated by electrochemical testing that the electrode with close-packed AgNPs provided high GOx loading (Γ=4.80 × 10⁻¹⁰ mol•cm⁻²) and fast electron transfer rate (k_s=5.76 s⁻¹). By employing GOx based-electrode as anode and laccase based-electrode as cathode, the assembled enzymatic biofuel cell exhibited a maximum power density of 77.437 μW•cm⁻² and an open-circuit voltage of 0.705 V.