Fully Assembled Membraneless Glucose Biofuel Cell With MWCNT Modified Pencil Graphite Leads as Novel Bioelectrodes.

This paper demonstrates the performance of single compartment membraneless glucose biofuel cell (GBFC) with pencil graphite leads (PGLs) as the substrate for bioanode and biocathode. Five grades of pencils, namely, B, HB, H, 3H, and 5H were rationally selected to fabricate the electrodes separately using enzyme nanobiocomposite-laccase/carboxylic functionalized multiwalled carbon nanotube (COOH-MWCNT) for biocathode and glucose oxidase/COOH-MWCNT for bioanode. GBFCs were assembled with these bioelectrodes and tested for power density, current density, and open circuit voltage (OCV) in two sets of experiments. In set-1, biocathode was fixed as 5H-grade PGL electrode, and in set-2, bioanode was fixed as B-grade PGL electrode, respectively, and the counter electrode was varied in each assembly between the selected grades. In both sets of results, the highest OCV and maximum power output with maximum current density were observed for the anode-cathode combination of B-5H. For the first time, this paper successfully establishes the potential of cost-effective readily available PGLs as promising alternatives to the carbon-based substrates for GBFCs. Furthermore, the cost- and time-efficient fabrication procedure also supports the novelty of their use. The relatively low overall output is suitably compensated by the unique advantages offered by the PGLs, thus increasing the scope of their applicability to miniaturized bioelectronic devices.