High-value activated carbons preparation from Enteromorpha prolifera and their electrochemical assessment

The excessive proliferation of Enteromorpha prolifera (EN) has adverse effects on marine ecological balance and the economic development of coastal regions. As an organic-rich biomass, the resource utilisation of EN is widely recommended. To convert the excess EN into high-value products, activated carbons were prepared via pyrolysis using H3PO4, ZnCl2, and KOH as activating agents in this study, and their application potentials for supercapacitors were also systematically investigated. The detailed activation mechanisms were provided based on the thermogravimetric-infrared analysis. Structure characterisation and chemical functional groups of the activated carbons were further explored to illustrate the effects of different activators and temperatures, and the results demonstrate that the optimal activation temperatures for H3PO4, ZnCl2, and KOH were around 600 °C, 500 °C, and 800 °C, respectively. During the electrochemical assessment of these activated carbons, the KOH-activated carbon (KEN-800) exhibited remarkable electrochemical performance. At a current density of 1 A/g, KEN-800 achieved a specific capacitance of 256 F/g, and its supercapacitor maintained a power density of 249.75 W/kg at an energy density of 6.87 Wh/kg. These findings provide valuable insights into the high-value conversion of EN and the effective application of EN-derived activated carbon, offering a novel approach for the management of EN waste.