Abstract

ARREDONDO-FERRER, Estefanía; BUITRAGO-SIERRA, Robison  and  LOPEZ, Diana. Hierarchical carbonaceous materials derived from spent coffee grounds for application in supercapacitors. Rev. acad. colomb. cienc. exact. fis. nat. [online]. 2022, vol.46, n.178, pp.233-247.  Epub Sep 10, 2023. ISSN 0370-3908.  https://doi.org/10.18257/raccefyn.1585.

The use of spent coffee grounds residues to obtain activated carbons by hydrothermal carbonization has not been approached in a systematic way in the literature, which, added to the need for improved energy storage systems, requires systematic studies of these processes. Here we obtained activated carbons with hierarchical porosity from biomass through hydrothermal carbonization and chemical activations. We analyzed the effect of the time and temperature of the hydrothermal carbonization of spent coffee grounds to obtain a high degree of carbonization and better reaction yields. As for the porosity, we used three structural directors to obtain a hierarchical pore distribution. Regarding the development of materials, the thermogravimetric and elemental analyses confirmed that hydrothermal carbonization at 250 °C for 6 h yielded much more carbonized material while at 200 °C for 6 h, a higher reaction performance was achieved. We also characterized the activated coals by isotherms and SEM micrographs to ensure the porosity and surface area required for obtaining a hierarchical distribution of pores in all the synthesized materials. Likewise, we evaluated their behavior as electrodes for supercapacitors obtaining a better specific capacitance with the carbon obtained by activation with potassium hydroxide (KOH).

Keywords : Spent coffee grounds; Hydrothermal carbonization; Chemical activation; Supercapacitors; EDLC.

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