Multifunctional carbon materials from rugose rose for energy storage and water purification

With the advancement of social process, the resource problem is becoming more prominent, biomass materials come into being, and it is becoming more and more important to explore and prepare efficient and multifunctional biomass materials to alleviate the problems of energy storage and water pollution. In this paper, nitrogen-doped hierarchical porous carbon materials (NRRC) were produced by one-step carbonization of withered rose as raw material and melamine as nitrogen source with KOH-activated porosification. The resulting nitrogen-doped porous carbon material had the most abundant pores and the best microspherical graded pore structure, with a specific surface area of up to 1393 m²·g⁻¹, a pore volume of 0.68 cm³·g⁻¹, and a nitrogen-doped content of 5.52%. Electrochemical tests showed that the maximum specific capacitance of NRRC in the three-electrode system was 346.4 F·g⁻¹ (0.5 A·g⁻¹), which was combined with favorable capacitance retention performance and cycling stability. The NRRC//NRRC symmetric supercapacitors were further assembled, and the maximum energy density of a single device was 23.88 Wh·kg⁻¹, which still maintains excellent capacitance retention and cyclic charging/discharging stability. For example, the capacitance retention rate was always close to 96.27% with almost negligible capacitance loss after 10000 consecutive charge/discharge cycles (current density: 10 A·g⁻¹). Regardless of the three-electrode or two-electrode system, the super capacitive performance of NRRC porous carbon materials was comparable to the electrochemical performance of many reported biomass porous carbon materials, which showed better energy storage advantages and practical application potential. In addition, NRRC porous carbon materials had excellent water purification ability. The dye adsorption test confirmed that NRRC had a high adsorption capacity (491.47 mg·g⁻¹) for methylene blue. This undoubtedly also showed a potential and promising avenue for high value-added utilization of this material.