Nitrogen configuration modulation of porous graphitic carbon nanosheets for superior capacitive energy storage

• Published in: Journal of power sources Vol. 614; p. 235027
• Main Authors: Sun, Yangkai, He, Zijian, Fan, Huiyang, Wang, Shurong
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.09.2024
• Subjects: Carbon nanosheets; DFT calculations; Nitrogen configuration modulation; Porous graphitic structure; Supercapacitor; Supercapacitor; Carbon nanosheets; Porous graphitic structure; Nitrogen configuration modulation; DFT calculations
• ISSN: 0378-7753
• DOI: 10.1016/j.jpowsour.2024.235027

Carbon nanosheets with layer-stacked porous structures and surface functionalized groups are beneficial for efficient ion storage in supercapacitor electrode materials, but achieving high cost-effectiveness and controllable surface groups remains a significant challenge. Herein, the biomass-derived chitosan and sodium alginate are selected as raw materials for self-assembly reaction with phytic acid as a cross-linking agent. The protonated chitosan and sodium alginate form a cross-linked network structure through hydrogen bonding and electrostatic adsorption, which is subsequently carbonized and activated to synthesize porous graphitic carbon nanosheets (PNPCN-X). PNPCN-X realizes an efficient distribution of porous and graphitic structures. It's noteworthy that phytic acid facilitates the fixation of N atoms, and various N configurations can be adjusted by altering the content of phytic acid. Optimized PNPCN-1.5 exhibits a high content of structurally stable pyridinic-N and graphitic-N configurations, which are confirmed to serve as active sites substantially augmenting the ion adsorption capacity through Density Functional Theory (DFT) calculations. Benefiting from its exceptional physicochemical properties, PNPCN-1.5 achieves 322 F g−1 as electrode materials in the three-electrode system, while the symmetrical supercapacitor assembled with EMIMBF4 electrolyte attains 56.29 W h kg−1. Furthermore, various kinetic analyses extensively elucidate its capacitance distribution characteristics and ion diffusion rates. [Display omitted] •Synthesizing porous graphitic carbon nanosheets by self-assembly of biomass derivatives.•Phytic acid induces precise modulation of N configurations.•High pyridinic-N and graphitic-N promote high specific capacitance and electrochemical stability.•DFT calculations and kinetic analysis reveal the electrochemical reaction mechanism.