Ultralight and compressible mussel-inspired dopamine-conjugated poly(aspartic acid)/Fe3+-multifunctionalized graphene aerogel
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The reduced graphene oxide (rGO) aerogels are particularly attractive owing to their ultralight-weight, high surface area and interconnected macroporosity for energy storage applications. However, pure rGO aerogels are generally weak and brittle to limit their practical applications. To overcome this drawback, a small amount of synthetic dopamine-conjugated poly(aspartic acid) was mixed with graphene oxide to fabricate ultralight rGO aerogels with high porosity and mechanical integrity via hydrothermal reactions at 80 °C and freeze-drying process. In addition, the Fe3+ ionic species was chosen for an additional cross-linker to further strengthen the ultralight poly(aspartic acid/dopamine) functionalized rGO aerogel, abbreviation for PAAD/rGO, through the coordination bonding between Fe3+ and carboxylic acid or catechol groups of both polymer and rGO sheets at pH 9 (PAAD/rGO-Fe❾). The hybrid electrodes of PAAD/rGO-Fe❾ showed the reversible transformation of the Fe3+ tris-catecholate complexes into mono-catecholate promoting Quinone (Q)-hydroquinone (QH2) in 1.0 mol L−1 H2SO4 electrolyte, thus delivering a high specific capacitance of 276.4 F g−1 at 0.5 A g−1 and capacitance retention of 88.2% after 5000 cycles. Moreover, this compressible aerogel provided high strength with 150 kPa without noticeable structural fracture after 80% compression and repeated deformation processes suggesting applications in energy storage and absorption.
This work was supported by the Basic Science Research Program through the National Research Foundation (NRF) of Korea, funded by the Ministry of Education, Science and Technology (NRF-2016R1D1A1A09918727).
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