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Super-hierarchical carbons with a unique carbonaceous hybrid nanotube-interconnected porous network were fabricated by utilizing well-defined carbon nanotube@polystyrene bottlebrushes as building blocks., Advances in the performances of many modern materials fundamentally depend upon the exploitation of new micro/nanostructures. Therefore, ingenious design of hierarchical structures through the mimicking of natural systems is of increasing importance. Currently, there is an urgent need for creation of multidimensional carbonaceous structures by integrating a customized hierarchical pore architecture and hybrid carbon framework. Here we report the pioneering fabrication of novel super-hierarchical carbons with a unique carbonaceous hybrid nanotube-interconnected porous network structure by utilizing well-defined carbon nanotube@polystyrene bottlebrushes as building blocks. Hypercrosslinking of such heterogeneous core–shell structured building blocks not only allows for constructing amorphous microporous carbon shells on the surface of graphitic carbon nanotube cores, but also leads to formation of covalently interconnected nanoscale networks. Benefiting from such a well-orchestrated structure, these super-hierarchical carbons exhibit good electrochemical performances. Our findings may open up a new avenue for fabrication of unique and unusual functional carbon materials which possess well-orchestrated structural hierarchy and thus generate valuable breakthroughs in many applications including energy, adsorption, separation, catalysis and medicine.

Powdery carbon aerogels (PCAs) for use as electrode materials in high-voltage aqueous supercapacitors were prepared from nanospheres of 1,2-divinylbenzene-styrene copolymer after carbonyl crosslinking. The effect of the size and carbonyl crosslinking conditions of the nanospheres on the microstructure and electrochemical properties of the PCAs were investigated. Results indicated that the size of the nanospheres, the crosslinking temperature and time played important roles in tailoring the nanostructures and electrochemical performance of the PCAs. All the PCAs had a well-defined 3D network and a hierarchical pore structure with a high porosity. The network units were between 25 and 100 nm in size, and the Brunauer-Emmett-Teller (BET) specific surface areas were from 392 to 767 m2g-1. The PCA with a BET surface area of 657 m2g-1 had a high electrochemical active surface area, a large capacitance and high capacitance retention rates at high current densities when used as electrodes in a 1.8 V aqueous supercapacitor using a Na2SO4 aqueous electrolyte. The use of a high-voltage aqueous electrolyte significantly increased the energy density of the supercapacitors.

In this paper, the mechanism of the reaction of activated carbon fibers (ACFs) with oxidants was studied by means of elemental analysis, surface groups analysis, X-ray photoelectron spectroscopy, gas chromatography, pH determination, and other techniques. The experimental results indicated that the reduction ability of ACF is mainly associated with the edges rather than the surface of the microcrystal carbon. The oxygen-containing functions can contribute only a small part of the reduction capacities of ACF. When ACF is oxidized by oxidants, the oxygen content and the amounts of hydroxyl, carbonyl, and carboxyl groups of ACF increase. The oxidation of ACF involves at least two processes, which are the formations of hydroxyl (or phenolic) groups and of carbonyl (or carboxyl) groups. Furthermore, the oxidation of ACF produces carbon dioxide and H + ion. The reduction capacity was larger than the amount of carbon dioxide released but approximately equal to the H + produced.

The redox characteristics of different ACFs were studied by use of X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and other analytic methods. The experimental results indicated that reducing properties are characteristic for ACF. All ACFs have reduction ability and can reduce ions of higher standard potentials to elemental metals or lower-valence compounds or ions. The reduction capacity of ACF is closely related to the standard potential of the oxidant used. The factors that are advantageous to the increase of standard potential of oxidants or decrease of potential of the ACF will be advantageous to the increase of reduction capacity. In bicomponent systems, ACF reacts primarily with the oxidant of higher potential.