Screening various pencil leads coated with MWCNT and PANI as enzymatic biofuel cell biocathode

Research in Enzymatic Biofuel cells (EBFCs) has evolved during the last decade. However, challenges, such as cost and endurance are the bottlenecks in harnessing their commercialization potential. To overcome these challenges, low cost, readily available pencil leads of various grades modified with polyaniline (PANI) and multi walled carbon nano tubes (MWCNT) have been examined as EBFC biocathode. Total four pencils of various grades (B, H, 3H, and 5H) were used to fabricate biocathode by covalently immobilizing Laccase(Lac) enzyme on to MWCNT coated (BC₁) and electrodeposited polyaniline and MWCNT coated (BC₂) on the surface of pencil graphite electrodes (PGEs). The fabricated biocathodes were characterized by scanning electron microscopy (SEM), BET surface area and conductivity measurements and electrochemical analysis was performed by the Open circuit potential (OCP) and Cyclic voltammetry (CV). Among the pencils tested in this work, the 5H pencil coated with PANI/MWCNT/Lacexhibited highest current density of 1209.23 μA/cm² with OCP of 0.528 V. Moreover, the PANI/MWCNT/Lac modified PGEs showed significant enhancement (80%) in electrochemical behavior when compared with unmodified (bare) and MWCNT/Lac coated PGE. Both types of Bioelectrodes (PGE/MWCNT/Lac,PGE/PANI/MWCNT/Lac) showed good stability and maximum conservation of its activity during the experiments.