Bioinspired Synthesis of Melaninlike Nanoparticles for Highly N-Doped Carbons Utilized as Enhanced CO2 Adsorbents and Efficient Oxygen Reduction Catalysts

Abstract

Highly N-doped nanoporous carbons have been of great interest as a high uptake CO2 adsorbent and as an efficient metal-free oxygen reduction reaction (ORR) catalyst. Therefore, it is essential to produce porosity-tunable and highly N-doped carbons through cost-effective means. Herein, we introduce the bioinspired synthesis of a monodisperse and N-enriched melaninlike polymer (MP) resembling the sepia biopolymer (SP) from oceanic cuttlefish. These polymers were subsequently utilized for highly N-doped synthetic carbon (MC) and biomass carbon (SC) spheres. An adequate CO2 activation process fine-tunes the ultramicroporosity (˂1 nm) of N-doped MC and SC spheres, those with maximum ultramicroporosities of which show remarkable CO2 adsorption capacities. In addition, N-doped MC and SC with ultrahigh surface areas of 2677 and 2506 m(2)/g, respectively, showed excellent ORR activities with a favored four electron reduction pathway, long-term durability, and better methanol tolerance, comparable to a commercial Pt-based catalyst.