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Multifunctional, Self-Activating Oxygen-Rich Holey Carbon Monolith Derived from Agarose Biopolymer

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journal contribution
posted on 2017-08-29, 19:19 authored by Vikrant Sahu, Ram Bhagat Marichi, Gurmeet Singh, Raj Kishore Sharma
Agarose, a natural biopolymer, is carbonized to synthesize an economical lightweight (0.05 g cm–3) mesoporous carbon monolith with large BET surface area (625 m2 g–1). The monolith prepared at different temperatures (700, 800, 900 °C) exhibits interesting morphologies without using any activating agent. The holey pattern appearing at 900 °C, besides increasing the meso/microporosity, confirms the self-activation at higher temperature. Most interestingly, the thick sheet-like morphology obtained at 700 °C is changed to nanoporous carbon flakes as the synthesizing temperature is increased to 800 and 900 °C. This synthesis approach affords an oxygen-enriched meso/microporous carbon monolith that constitutes high pseudocapacitance in addition to electric double layer charge. Lightweight carbon monolith exhibits excellent thermal and mechanical characteristics having a weight bearing capacity of ∼5900 times compared to its weight without developing any deformity. The electrochemical performance of carbonized agarose (CAR) tested in 1 M H2SO4 exhibits superior charge storage capacity in CAR 900 (302 F g–1 at 5 mV s–1) compared to that of CAR 800 (124 F g–1) and CAR 700 (107 F g–1). The symmetric cell (1 × 1 cm2 area) fabricated using CAR 900 as electrodes exhibits excellent cell performance over 5000 charge/discharge cycles with ∼98% capacity retention. Three symmetric CAR 900 cells connected in series enable powering a red LED bulb (3 V) that indicates excellent sustainability of agarose-derived carbon in energy storage devices.