Nitrogen-doped (N-doped) nanoporous carbonaceous materials have recently shown a significant impact on the research areas of energy storage and conversion including electrodes for fuel cell and CO2 adsorbents and so on. Herein, we report a highly N-doped nanoporous carbon spheres synthesized from melanin-like polymer (MP) and sepia from squid in the seawater, and utilization of such carbon samples as CO2 adsorbents and metal free Oxygen Reduction Reaction (ORR) catalysts. First, monodisperse MP with size of 100-500 nm was synthesized using a dopamine precursor. As prepared MP was carefully characterized by FT-IR, UV-vis spectrometer, SEM, EA (elemental analysis), 13C solid state NMR, and it turned out that the chemical and structural features resembled sepia from squid in the seawater: The sepia is a natural melanin and it shows spherical shape with 100-200 nm in size. Nitrogen-enriched MP and sepia polymer (SP) from squid were then carbonized to provide highly N-doped and monodisperse carbons of which nitrogen content was as high as 12 wt%. Highly N-doped melanin-like carbon (MC) and sepia carbon (SC) were then activated to increase specific surface area and pore volume as well as control the pore size distribution (PSD) by hot CO2 treatment: for example, surface area of 2677 m2/g and pore volume of 1.72 cm3/g for MC, and surface area of 2506 m2/g and pore volume of 1.47 cm3/g for SC. Highly N-doped and largely developed ultramicropore (&lt; 1 nm) for activated MC and SC samples, which have been known for key factors for enhancing CO2 adsorption, were then utilized as CO2 adsorbents, and one of which shows outstanding CO2 adsorption capacities of 7.8 mmolg-1 at 273K and 4.8 mmolg-1 at 298K (1bar). In addition, as a metal free ORR catalyst, highly N-doped MC and SC with large surface areas of 2677 m2/g and 2506 m2/g, respectively, show excellent activity for ORR, which is comparable ORR performance to commercial Pt-based catalyst. It is noted that largely developed surface areas with mesoporosity and numerously created active catalytic nitrogen sites of MC and SC samples favored four-electron reduction pathway, which is important factor for a promising Pt-free ORR catalyst.

Bioinispired preparation of melanin-like nanoparticles used for highly nitrogen-doped porous carbon spheres: Enhanced CO2 capacities and efficient oxygen reduction catalyst

253rd National Meeting (2017)

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