Desenvolvimento de eletrodos para supercapacitores eletroquímicos a partir de biomassa de Saccharomyces Cerevisiae ancorada com nanopartículas metálicas biossíntetizadas

Abstract

The global increase in energy consumption and the predominance of 9léctr fuels have intensified problems related to the scarcity of natural resources, environmental pollution, and global warming. In this 9léctron, interest in renewable energy sources and 9léctron9 energy storage systems has been growing. Electrochemical supercapacitors stand out due to their high power density, long cycle life, and low environmental impact. Among the materials used for electrode fabrication, biomass-derived carbons have attracted attention because they combine electrochemical performance and sustainability. In this 9léctron, fungal biomass, particularly the yeast Saccharomyces cerevisiae, shows potential due to its rapid growth, wide availability, and ability to mediate the biosynthesis of metallic nanoparticles (MNPs). Therefore, this study aimed to perform the biosynthesis of silver nanoparticles (AgNPs), gold nanoparticles (AuNPs), and bimetallic silver/gold nanoparticles (Ag/AuNPs) using S. cerevisiae biomass, aiming to obtain carbonaceous materials with anchored MNPs for application in electrochemical supercapacitor electrodes. The proposed strategy seeks to integrate MNP biosynthesis and their incorporation into the biomass within a single approach, as an alternative to conventional methods that may require higher energy consumption and the use of potentially toxic 9léctron9. The results confirmed the formation of MNPs by UV-Vis spectroscopy, with surface plasmon resonance bands at 410 nm for AgNPs and 545 nm for AuNPs. For the material containing Ag/AuNPs, a band was observed at 554 nm, shifting to 543 nm throughout the biosynthetic process. X-ray diffraction analyses revealed peaks at 38.50°, 44.18°, 64.76°, and 77.80°, assigned to the (111), (200), (220), and (311) crystallographic planes, respectively, while energy-dispersive X-ray spectroscopy confirmed the presence of Ag and Au in the respective materials. Transmission 9léctron microscopy micrographs revealed nanoparticles ranging from 25 to 80 nm. Thermogravimetric analyses indicated final carbonaceous material yields of 5.70%, 5.80%, 12.70%, and 17.80% for the samples without NPs, with AgNPs, with AuNPs, and with Ag/AuNPs, respectively. In the electrochemical evaluation by cyclic voltammetry, the materials containing AgNPs, AuNPs, and Ag/AuNPs exhibited maximum specific capacitances of 466.00, 382.00, and 395.00 F g⁻¹, respectively, corresponding to increases of 202.06%, 134.36%, and 156.49% compared with the material without NPs. In galvanostatic chargedischarge tests, capacitance retentions after 1000 cycles were 88.94%, 83.01%, and 94.50%, respectively. These results demonstrate the potential of S. cerevisiae biomass as a sustainable platform for the biosynthesis of MNPs and the production of advanced carbonaceous materials for the development of electrochemical supercapacitor electrodes