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

Abstract

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 m 2 •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.

Core–shell Mo2C@NC/Mo2C hollow microspheres as highly efficient electrocatalysts for the hydrogen evolution reaction

“…The CN oligomer finally reacts with furfural to form a composite composed of the CN polymer and hydrothermal carbon (HTC) as the shell. 22 Meanwhile, hexaammonium molybdate hydrolyzes into MoO 2 particles and disperses inside and outside of the HTC carbon composite in a high-temperature and high-pressure atmosphere. 23 The nitrogen-containing HTC would react with MoO 2 to form core–shell Mo 2 C@NC hollow microspheres embedded with Mo 2 C due to the decomposition of the CN polymer in a pyrolysis process in an H 2 environment.…”

Improving the performance of biomass-based electrocatalysts by means of hot pressing

“…[6][7][8] As various methods for the synthesis of biomassbased electrocatalysts have different effects on their resulting properties, recent reports in the literature focus on how to improve the electrocatalytic performance by optimizing preparation conditions. [9][10][11][12][13][14] Because of some natural features of biomass, the production of biomass-based electrocatalysts normally requires high temperatures and the addition of extrinsic agents which are exemplified by dopant species (metals or nonmetals) and poreforming agents to achieve high catalytic activities. [15][16][17] This treatment can be understood to a large extent by appreciating that raw biomass is indeed an electrical insulator and also by recognizing that quantities of active species that are inherent in biomass are too small to lead to an acceptable level of performance.…”

“…6–8 As various methods for the synthesis of biomass-based electrocatalysts have different effects on their resulting properties, recent reports in the literature focus on how to improve the electrocatalytic performance by optimizing preparation conditions. 9–14…”

Guanosine-assisted synthesis of a core–shell Mo2N/Mo2C/C structure for enhanced hydrogen evolution reaction

“…Furthermore, the abundant interactions present in guanosine, such as hydrogen bonding and π-π stacking, make it a favored choice for synthesizing various carbon material morphologies. [31][32][33] In this study, we utilized guanosine as a supramolecular precursor, acting as a source of both carbon and nitrogen, to induce the formation of new Mo-based structures through intrinsic selfregulating mechanisms. Through the hydrothermal carbonization method, a core-shell spherical MoO 2 /CN polymer was successfully formed.…”