Doubling Micropore of Carbon Skeleton via Regulating Molecular Structure of Carbohydrate for Oxygen Reduction Reaction

Abstract Functional carbon materials prepared from biomass-derived carbohydrates have attracted extensive interest due to their low cost and high catalytic potential for oxygen reduction reaction (ORR). In this work, the pyranose ring, which is the basic repeating unit in lignocellulosic biomass, can be easily converted into micropore-riched carbon skeleton via regulating the side chain C-containing group. In striking contrast to glucopyranose, the simple pyranose ring (xylopyranose) exhibits outstanding nitrogen fixation ability. But higher N content in the carbon skeleton can lead to a decrease in C content, which is detrimental to the graphitization and pore-forming of carbon product. Benefiting from abundant micropore structures (volume increases from 0.22 to 0.50 cm3 g−1), the electrochemical surface area of Glu-SSC-950 is much larger than that of Xyl-SSC-950 and the double layer capacitance of Glu-SSC-950 (14.9 mF cm−2) is more than twice that of Xyl-SSC-950 (6.4 mF cm−2). Furthermore, the Glu-SSC-950 displays a more positive half-wave potential (0.84 V) and higher peak power density of Al-air battery (467.8 mW cm−2) compared with Xyl-SSC-950 (0.76 V and 373.6 mW cm−2). In general, it compensates for the shortcomings of the screening of carbohydrate precursors for preparing ORR carbonaceous electrocatalysts.