Abstract
In this study, ultrahigh electrochemical performance for interconnected meso/macro-porous 2D C@α-Fe2O3 synthesized via sucrose-assisted microwave combustion is demonstrated. Hematite (α-Fe2O3) synthesized via the same approach gave an encouraging electrochemical performance close to its theoretical value, justifying its consideration as a potential supercapacitor electrode material; nonetheless, its specific capacitance was still low. The pore size distribution as well as the specific surface of bare α-Fe2O3 improved from 145 m2 g−1 to 297.3 m2 g−1 after it was coated with sucrose, which was endowed with ordered symmetric single-layer graphene (2D graphene). Accordingly, the optimized hematite material (2D C@α-Fe2O3) showed a specific capacitance of 1876.7 F g−1 at a current density of 1 A g−1 and capacity retention of 95.9% after 4000 cycles. Moreover, the material exhibited an ultrahigh energy density of 93.8 W h kg−1 at a power density of 150 W kg−1. The synergistic effect created by carbon-coating α-Fe2O3 resulted in modest electrochemical performance owing to extremely low charge transfer resistance at the electrode–electrolyte interface with many active sites for ionic reactions and efficient diffusion process. This 2D C@α-Fe2O3 electrode material has the capacity to develop into a cost-effective and stable electrode for future high-energy-capacity supercapacitors.
Highlights
With the exponential growth of technology and increase in energy crises in the 21st century with respect to the numerous energy generation approaches, insistence for green and effective energy production has become a global concern
It could be observed that the peaks of bare hexagonal a-Fe2O3 are at the same position but more crystalline than those of 2D C@aFe2O3, and this is due to the presence of the carbon in sucrose, and it portrays itself with a very weak hump in the 2 theta range of 43.7 to 43.8 and 22.7 to 22.8 with planes of (101) and (002) respectively
The disordered D band arises as a result of hybridized vibrational modes associated with graphitic edges in the form of defects in the sample, while the G band is ascribed to the C–C bond stretching vibration in graphitic materials, which is commonly associated with sp[2] hybridized carbon systems.[42]
Summary
With the exponential growth of technology and increase in energy crises in the 21st century with respect to the numerous energy generation approaches, insistence for green and effective energy production has become a global concern. Carbon derived from sucrose can attain a high speci c surface area of 1941 m2 gÀ1 and relatively high speci c capacitance.[32] Microporous, macroporous and mesoporous carbon structures have been widely studied for various energy storage systems including supercapacitors.[33,34] Porous carbon structures endowed with hierarchical macro–meso–micro porosities promote fast ion transport that minimizes the diffusion distance between the electrode and electrolytes and reduces the volume change during the charge/discharge cycling, which primarily improves supercapacitor performance.[35,36,37] a cost effective and green method to synthesize porous carbon materials with tunable pore sizes still poses an enormous challenge.[38] There have been several reports on sucrose being employed to composites or to enhance the performance of supercapacitor electrode materials, but to the best of our knowledge, no report has been published in light of this 2D C@a-Fe2O3 electrode material's synthesis scheme and electrochemical performance. This exceptional morphology gave an ultrahigh speci c capacitance and energy density comparatively with very good mechanical stability a er a reasonable cycle runtime
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