New laccase-based catalysts to improve oxygen reduction reactions (ORR) are described, and enzymatic biofuel cells (EBCs) adopting these catalysts were developed. These new catalysts are synthesized by combining laccase, poly(ethylenimine) and carbon nanotubes, with attachment of selected elements using the crosslinker, glutaraldehyde (GA). Several characterization approaches are implemented to evaluate catalytic electron transfer in both the absence and presence of mediators and their effects on glucose/O2 biofuel cell performance. [CNT/Lac/PEI/Lac]/GA shows that the best electron transfer rate constants (ks) achieved, in the presence as well as the absence of a mediator, are 8.6 and 1.8s-1. Additionally, [CNT/Lac/PEI/Lac]/GA results in high performance of Maximum Power Density with a value of 0.2mWcm-2. Its relative stability can be maintained up to 83.76% with relative efficiency up to 84.73%, while CNT/Lac gives the lowest performance levels. This indicates that GA induces an improvement in catalytic activity by (i) increasing the amount of immobilized laccase and (ii) strengthening interaction between laccase and PEI. Therefore, it induces excellent redox reactivity, promoting the ORR, and glucose/O2 biofuel cell performance. The effect of pH on catalytic activity is also measured, with pH 5 being optimal.
Keywords: Glucose/O(2) biofuel cells; Glutaraldehyde; Laccase; Oxygen reduction reaction; Poly(ethylenimine).
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