Green Conversion of Microalgae into High-Performance Sponge-Like Nitrogen-Enriched Carbon

The selective conversion of biomass into high-value carbon materials has recently been attracting increasing attraction. In this study, a microalga with a high nitrogen content, namely Spirulina platensis, was used as both the carbon and nitrogen precursors in the synthesis of sponge-like nitrogen-enriched carbon materials through a one-step activation method with NaHCO3 as a green activator. The sponge-like nitrogen-enriched carbon materials obtained at different activation temperatures were systematically characterized by using SEM, N-2 adsorption-desorption, XRD, Raman, and XPS techniques. A series of tests were performed to investigate the electrochemical characteristics of the obtained carbon materials to determine their potential use as supercapacitors. The results show that sponge-like nitrogen-enriched carbon activated at 700 degrees C, which has a large BET surface area of 865 m(2)/g and a high nitrogen content of 7.5 wt%, gave the largest specific capacitance of 234.0 F/g at a current density of 1 A/g in a 6 M KOH electrolyte.