Constructing Thinner Micropore-Riched Carbon Skeleton Through Molecular Configuration Transformation of Hexose Isomers to Boost Oxygen Reduction Reaction

Oxygen reduction reaction (ORR) is the core process of metal-air battery. Functional carbon-based materials are promising electrocatalysts for ORR. In this work, the molecular configuration transformation between pyranose (glucose) and furanose (fructose) is selected as an entry point to construct thinner micropore-riched carbon skeleton with high amount of active sites. The molecular configuration transformation from furanose to pyranose increases the activation barrier associated with the molecular conversion, self-assembly, and aromatization reaction. The higher activation barrier slows the dynamic pyrolysis process, which favors the pore-forming and graphitization of precursors. The Glu-SSC-950-1 (derived from pyranose) exhibits the larger electrochemical active surface area (ECSA) and faster electron transfer, concretely, double-layer capacitance increases from 7.4 to 14.9 mF cm−2. And the Glu-SSC-950-1 exhibits a higher half-wave potential (0.847 V) and kinetic current density at half-wave potential (3.91 mA cm−2) than Fru-SSC-950-1 (derived from furanose, 0.801 V, 2.92 mA cm−2). In practical application, the Al-air battery with Glu-SSC-950-1 exhibits a superior peak power density (467.8 mW cm−2) than Fru-SSC-950-1 (400.7 mW cm−2). In general, we present a novel prejudging approach on the porosity of the carbonization products, which is useful for screening the organic precursors for the preparation of highly active ORR carbon-based materials