Carbon Nanocubes Research Articles

Multi-chambered micro/mesoporous carbon nanocubes as new polysulfides reserviors for lithium–sulfur batteries with long cycle life

Achieving rechargeable batteries with high-energy density, long cycle life and excellent rate capability is of significant importance for a vast energy-consuming society. Lithium sulfur (Li–S) batteries, attracting extensive attentions, are regarded as one of the most promising energy storage system. However, Li–S batteries are facing big challenges, owing to the fast capacity degradation, low Coulombic efficiency and poor rate capabilities. By adopting a dual confinement strategy, we successfully synthesized homogenous poly(3,4-ethylenedioxythiophene) (PEDOT) coated multi-chambered micro/mesoporous carbon nanocube encapsulated sulfur (P@CNC-S) composites. Sulfur is impregnated in individual interconnected multi-chambered micro/mesoporous carbon nanocubes, which act as the physical confinement and multilayered reservoirs for soluble lithium polysulfides. The PEDOT conductive polymer provides chemical bondings to soluble lithium polysulfides. When applied as cathodes in Li–S batteries, the P@CNC-S composites exhibited superior performances, including high specific capacities, long cycle life and outstanding high rate capabilities. Ex-situ TEM analysis confirmed the successful confinement of the dissolution of lithium polysulfides and volume expansion of the discharged product (Li2S), which could contribute to the high Coulombic efficiency and excellent cyclabilities.

Mesoporous Carbon Nanocube Architecture for High‐Performance Lithium–Oxygen Batteries

One of the major challenges to develop high‐performance lithium–oxygen (Li–O2) battery is to find effective cathode catalysts and design porous architecture for the promotion of both oxygen reduction reactions and oxygen evolution reactions. Herein, the synthesis of mesoporous carbon nanocubes as a new cathode nanoarchitecture for Li–O2 batteries is reported. The oxygen electrodes made of mesoporous carbon nanocubes contain numerously hierarchical mesopores and macropores, which can facilitate oxygen diffusion and electrolyte impregnation throughout the electrode, and provide sufficient spaces to accommodate insoluble discharge products. When they are applied as cathode catalysts, the Li–O2 cells deliver discharge capacities of 26 100 mA h g−1 at 200 mA g−1, which is much higher than that of commercial carbon black catalysts. Furthermore, the mesoporous nanocube architecture can also serve as a conductive host structure for other highly efficient catalysts. For instance, the Ru functionalized mesoporous carbon nanocubes show excellent catalytic activities toward oxygen evolution reactions. Li–O2 batteries with Ru functionalized mesoporous carbon nanocube catalysts demonstrate a high charge/discharge electrical energy efficiency of 86.2% at 200 mA g−1 under voltage limitation and a good cycling performance up to 120 cycles at 400 mA g−1 with the curtaining capacity of 1000 mA h g−1.

(Fe,Co)@nitrogen-doped graphitic carbon nanocubes derived from polydopamine-encapsulated metal-organic frameworks as a highly stable and selective non-precious oxygen reduction electrocatalyst.

A facile approach is reported to synthesize (Fe,Co)@nitrogen-doped graphitic carbon (NGC) nanocubes (NCs) via the pyrolysis of polydopamine-encapsulated Fe3[Co(CN)6]2 NCs at 700 °C. Besides the comparable catalytic activity for oxygen reduction reaction (ORR) to the Pt/C catalyst, it showed much more outstanding catalytic selectivity and superior durability.

Carbon Nanocubes and Nanobricks from Pyrolysis of Rice

Carbon nanocubes and nanobricks were synthesized by pyrolyzing rice powder at 600 degrees C under nitrogen atmosphere. Purification with concentrated nitric acid introduced approximately 0.1 mol/g of carboxylic acid groups as found by acid-base titrimetric analysis. XRD pattern showed the 0.15 mol/g basic graphitic structure of these nano carbon materials. Their SEM and TEM images revealed cube or brick shaped nano crystals. These nanocrystals are further characterized by FT-IR, Raman, and EDAX analysis. High density wrapping of carboxylated acid groups introduces surface passivation of these nano carbon cubes and nano carbon bricks exhibiting photoluminescence. Solid state electronic spectrum showed several bands in the ultraviolet and visible region and excitation at 336 and 474 nm generates photoluminescence respectively in the ultraviolet and visible region.