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Synergistic effects of nitrogen doping in waste-fruit peel-derived activated carbons for supercapacitors and water treatment
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DOI:10.1039/d6ra02137a.png)
Abstract
En 中文
Developing sustainable carbon materials from agricultural waste offers promising solutions to both energy-storage and water-treatment challenges. This study reports the synthesis of a nitrogen-doped Tondolo-derived activated carbon (N-TAC), an underexplored African wetland sedge whose fibrous morphology directs pore architecture. Rather than conventional dry mixing, K2CO3 and urea were co-dissolved and intimately blended with the finely reduced Tondolo precursor. This reagent-level homogeneity enabled a single pyrolysis at 700 degrees C in which carbonisation, chemical activation, and nitrogen doping proceeded concurrently. The N-TAC Near-surface nitrogen functionalities (pyridinic, pyrrolic, and graphitic) proved decisive in enhancing both electrochemical and adsorptive performance. Three-electrode characterization in 1 M NaNO3 revealed coexisting EDLC and pseudocapacitive mechanisms, with a low ESR of 2.05 Omega and relaxation time constant of 0.87 s confirming rapid ion diffusion kinetics. Trasatti deconvolution and Dunn's method reveal that pyridinic and pyrrolic sites selectively amplify pseudocapacitive contributions (63-71%) in the positive potential window, a window-dependent asymmetry not previously reported for neutral-electrolyte biomass carbons. The assembled symmetric device delivered 12.1 Wh kg(-1) with 94% capacitance retention after 10 000 cycles. For water remediation, N-TAC achieved 99.9% methylene blue removal at 50 ppm with an adsorption capacity of 557.6 mg g(-1), governed by chemisorption via electrostatic and pi-pi interactions, best described by pseudo-second-order kinetics (R-2 = 0.97) and the Temkin isotherm (R-2 = 0.958). These results position N-TAC as a competitive sustainable material at the water-energy nexus, with future perspectives including binder-free electrode fabrication, electrochemical degradation coupling, and regenerable architectures for long-term sustainability.
Keywords:
DOPED POROUS CARBONS
HIGH-SURFACE-AREA
PERFORMANCE
ADSORPTION
ELECTRODES
MICRO
STRATEGY
POROSITY
REMOVAL
BIOMASS
Journal
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4.6
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7.2K
Citations:
20.9W
