Multi walled carbon nanotube and polyaniline coated pencil graphite based bio-cathode for enzymatic biofuel cell

In the present work, two types of cost-effective bio-electrodes were fabricated by immobilizing Laccase on commercially available pencil graphite leads, and their electro catalytic activity have been examined. The first type of electrode (E₁) was fabricated by electro polymerization of polyaniline on pencil graphite leads on which multi walled carbon nanotubes (MWCNT) was immobilized by covalent bonding, while the second type of electrode (E₂) was fabricated by direct coating of MWCNT on pencil graphite leads. Two types of bio-cathodes were fabricated by immobilizing Laccase on the two types of electrodes by covalent bonding. The scanning electron microscopy (SEM) revealed three dimensional porous networks providing large surface area for enzyme immobilization. The maximum open circuit potential (OCP) for E₁ and E₂ bio-cathodes were measured 0.58 V and 0.60 V respectively vs Ag/AgCl reference electrode. The maximum current density observed for E₁ and E₂ electrodes were 295.7 μAcm^-2 and 228.94 μAcm^-2 respectively. Both electrodes exhibited excellent stability, conserving more than 75% of its optimum activity during the period of measurement.