Effect of Fluorination on the Activated Biocarbons Synthesized From Gracilaria edulis Biomass Employing Various Activating Agents for Supercapacitor Applications
Dhileepan Priyadharshini, Singaravelu VivekanandhanABSTRACT
Fluorination of the activated biocarbons synthesized from Gracilaria edulis (GE) biomass employing various chemical activating agents (FeCl 2 , NiCl 2 , and ZnCl 2 ) was performed effectively using hydrofluoric (HF) acid. The fluorine impregnation into activated biocarbon was confirmed through XPS analysis, which is found to be 2.3%, 1.0%, and 2.1%, respectively, for the GE‐FAC‐Fe, GE‐FAC‐Ni, and GE‐FAC‐Zn biocarbons. XRD and Raman analyses reveal the turbostratic structure of fluorinated activated biocarbons. Further, the synthesized biocarbon materials exhibited various functional groups (─OH, ─CH, C═O, C─O, and ─CF 2 ), which effectively promoted the electrolyte wettability. The fluorinated activated biocarbon materials showed the specific surface areas of 374, 307, and 324 m 2 /g, respectively, for the GE‐FAC‐Fe, GE‐FAC‐Ni, and GE‐FAC‐Zn biocarbon. The synthesized fluorinated biocarbon materials were effectively used as the electrode material for supercapacitor fabrication, in which GE‐FAC‐Fe biocarbon showed a superior specific capacitance of 137.77 F/g at 1 A/g employing 1 M KOH as electrolyte. Further, it showed a specific energy density of 4.59 Wh kg −1 at a specific power density of 551.6 W kg −1 . However, it exhibits only 63% capacity retention over 5000 cycles, which may be due to the fluorine loss.