New Family of Hydrothermal Carbons with Super-High Surface Areas Derived from Nucleosides for Oxygen Reduction

Hydrothermal carbonization (HTC) technology shows a powerful way to transform biomass into new carbonaceous materials. However, because of weak interactions between biomass, the nucleation/polymerization process of HTC carbon follows the random polymerization mechanism, tending to form spherical particles with very few micro/mesopores and very small surface areas. Herein, we report an acid-assisted HTC strategy to fabricate a new family of hydrothermal carbons with super-high surface areas from nucleoside precursors, namely, guanosine, adenosine, and inosine. Among them, HTC carbons derived from guanosine show obviously layered graphitic characteristics potentially owing to the strong multiple hydrogen bonding and π–π interaction between guanosine, while the materials prepared from inosine and adenosine are composed of large-size spherical carbon particles. Ex-situ characterizations confirm that guanosine first decomposes into guanine and ribose under acid-assisted HTC conditions to form bulky guanine sulfate. The guanine sulfate then self-assembles to CN oligomers; meanwhile, the ribose is dehydrated to furfural. The CN oligomer finally reacts with furfural to obtain the composite composed of layered CN polymers and HTC carbon. Owing to the self-templated effect, all HTC carbons can be transformed into carbon with ultrahigh surface areas (∼1700 m2·g–1) by further pyrolysis at 1000 °C. The electrochemical test indicates that these nucleoside-derived carbon materials have excellent activity in oxygen reduction reaction, especially for the guanosine-derived carbon, exhibiting excellent electrocatalytic activity with a half-wave potential of 0.88 V and a limit current density of 5.84 mA·cm–2, which are quite close to those of a commercial Pt/C catalyst.