Desenvolvimento de eletrodos para supercapacitores eletroquímicos de alto desempenho a partir de biomassa fúngica ancorada com nanopartículas metálicas biossintetizadas

Abstract

The improvement and development of energy storage devices is a rising field which aims at enabling to make the most of the energy generated by renewable sources, intervening in the problems related to intermittent energy production. Electrochemical capacitors are among these devices, and they stand out for their high potence density and long useful life, being ideal for application in electronic devices, electric vehicles, among others. Recent studies discuss the use of biomass-derived carbon materials for the development of electrodes for electrochemical supercapacitors. The use of fungus-derived biomass for the production of carbon materials has been attracting attention due to the rapid growth of fungi and the diversity of biomass sources. In addition to that, fungal biomass is also applied to the biosynthesis of metallic nanoparticles (MNPs), allowing the reduction or elimination of potentially dangerous chemical substances, prioritizing environmental, economic and efficiency issues. Recent studies report MNPs anchorage to carbon materials with the intention of improving capacitance and conductivity when applied to the development of supercapacitors. Despite the potentialities associated with the incorporation of MNPs to carbon materials for the increase of specific capacitance, MNPs synthesis classic methods and the anchorage to carbon materials make use of potentially toxic chemical substances and demand great energy consumption. MNPs anchorage to fungal biomass simultaneously to the intracellular biosynthesis process in a single step for the further production of a carbon material for the production of electrodes for supercapacitors is a feasible and sustainable alternative. Thus, the objective of this work was to carry out MNPs intracelular biosynthesis using fungal biomass of Coprinopsis calospora (CPC), pertaining to the phylum Basidiomycota, and of Penicillium flavigenum (PCF), pertaining to phylum Ascomycota, in order to produce carbon materials with anchored MNPs and their use in the development of electrodes for high performance electrochemical supercapacitors. By means of the results gathered, it was possible to attest that NPsAu and NPsAg intracellular biosynthesis mediated by the biomass of the mycelia of fungi CPC and PCF and the production of carbon fungi (CF) were successfully carried out. The electrochemical performance assessment by cyclic voltammetry (CV) of modified glassy carbon electrodes (GCEs) elicited that GCE_CFCPC_NPsAu and GCE_CFCPC_NPsAg presented maximum specific capacitance of 179.00 F g-1 and 208.33 F g -1 , respectively, indicating a 28.4% and 24.0% increase in relation to GCE_CFCPC in the respective supporting electrolytes assessed. The electrodes made from CF of the PCF fungus did not show significant differences with the presence of MNPs. Thus, differences in electrochemical stability were found between electrodes produced using CF from the fungus CPC and PCF, significantly influencing the performance of modified electrodes used in the development of electrochemical supercapacitors. The stability throughout the analyses for the GCE_CFCPC_NPsAu and GCE_CFCPC_NPSAg were assessed by galvanostatic charge and discharge (GCD) due to the excellent electrochemical performances among the assessed electrodes, showing retention of the maximum capacitance after 1,000 cycles of 97.67% and 98.68% respectively.