Direct electron transfer from glucose oxidase immobilized on a nano-porous glassy carbon electrode

► A direct electron transfer reaction of glucose oxidase was observed on the surface of a nano-porous glassy carbon electrode. ► A pair of well-defined and reversible redox peaks was observed at the formal potential of approximately −0.439 V. ► The apparent electron transfer rate constant was measured to be 5.27 s−1. ► A mechanism for the observed direct electron transfer reaction was proposed, which consists of a two-electron and a two-proton transfer.