Guoxu Wang

Hierarchical porous nitrogen-doped partial graphitized carbon monoliths for supercapacitor

AbstractPorous carbon monoliths have attracted great interest in many fields due to their easy availability, large specific surface area, desirable electronic conductivity, and tunable pore structure. In this work, hierarchical porous nitrogen-doped partial graphitized carbon monoliths (N–MC–Fe) with ordered mesoporous have been successfully synthesized by using resorcinol-formaldehyde as precursors, iron salts as catalyst, and mixed triblock copolymers as templates via a one-step hydrothermal method. In the reactant system, hexamethylenetetramine (HMT) is used as nitrogen source and one of the carbon precursors under hydrothermal conditions instead of using toxic formaldehyde. The N–MC–Fe show hierarchically porous structures, with interconnected macroporous and ordered hexagonally arranged mesoporous. Nitrogen element is in situ doped into carbon through decomposition of HMT. Iron catalyst is helpful to improve the graphitization degree and pore volume of N–MC–Fe. The synthesis strategy is user-friendly, cost-effective, and can be easily scaled up for production. As supercapacitors, the N–MC–Fe show good capacity with high specific capacitance and good electrochemical stability. Graphical abstractHierarchical porous nitrogen-doped partial graphitized carbon monoliths with ordered mesoporous have been successfully synthesized by using resorcinol-formaldehyde as precursors, iron as catalyst, and mixed triblock copolymers as templates via a one-step hydrothermal method.

Controllable synthesis of nitrogen-doped hollow carbon nanospheres with dopamine as precursor for CO2 capture

Nitrogen-doped hollow carbon nanospheres (N-HCSs) have been synthesized by self-polymerization of dopamine on silica spheres using the modified Stober method. The fabrication process uses dopamine as carbon and nitrogen source and tetraethyl orthosilicate as a structure-assisting agent. The particle sizes and shell thicknesses of the N-HCSs can be easily tuned in the range of 270–700 nm and 30–55 nm, respectively, by simply modifying the ethanol/water volume ratios. The surface areas of N-HCSs are in the range of 345–463 m2 g−1, and the total pore volumes are in the range of 0.34–0.52 cm3 g−1. The obtained N-HCSs have uniform mesoporous size of ∼4.0 nm, and high nitrogen loading content of 7.2 at%. Besides, the N-HCSs exhibit a considerable performance for CO2 capture with a capacity of 3.09 mmol g−1 at 25 °C and 1.0 bar and a good cycling stability.

Porous carbon derived from waste polystyrene foam for supercapacitor

Polystyrene, one of the classical plastic, has caused serious environmental problems due to overuse and inability to recycle effectively. Transforming it into functional carbon materials is one of the effective ways to recycle polystyrene and other waste plastics, which has drawn the attention. In this study, we have developed a facile and efficient method for the preparation of three-dimensional (3D) network structure porous carbon (PC) via the Friedel–Crafts reaction with waste polystyrene serves as carbon source. Notably, the constructed carbonyl (–CO–) cross-linking bridges between the linear polystyrenes provide the resulting hierarchical porous polystyrene with a high cross-linking density and amounts of oxygen atoms to achieve the carbonizability of cross-linking polystyrene framework. Moreover, silica particles created more porous structure for carbon material. The prepared PC showed large specific surface area and 3D porous structure and exhibited good capacitance and electrochemical stability as electrode materials for supercapacitor.

Synthesis of N-doped Carbon Spheres Using Extended Stöber Method for SO2 Adsorption

SO2 is one of the major pollutants in the atmosphere. N-doped microporous carbon spheres (NCS) have been demonstrated to be effective for SO2 adsorption. Here we report the synthesis of monodispersed NCS by the extended Stober method with urea resorcinol-formaldehyde resins as carbon source, urea as nitrogen source and ammonia as catalyst in an ethanol-water mixed solvent. The obtained carbon spheres show a uniform diameter of around 550nm, specific surface area of 476m2g−1, micropores pore volume of 0.20cm3g−1 and nitrogen doping. The NCS manifest special performance for SO2 capture with capability of 75.34mgg−1 and good cycling stability, due to the large surface area, abundant micropores and nitrogen functionality.

Biomass derived 5-hydroxymethylfurfural as carbon precursor to form hollow carbon nanospheres for CO2 capture

ABSTRACT We prepare the hollow carbon nanospheres (HCNs) by employing SiO2 nanospheres as hard template, 5-Hydroxymethylfurfural (HMF) as carbon precursor under hydrothermal conditions. The HCNs show uniform spherical morphology copied from SiO2 nanospheres and exhibit large cavity, thin shell structure with the surface area of 790 m2 g−1 and pore volume of 2.23 cm3 g−1. Owing to their large internal voids and high surface area, the HCNs exhibit a promising prospect for CO2 capture with the capacity of 3.04 mmol g−1 at 1.0 bar and 298 K, as well as good recyclability for CO2 after ten adsorption-desorption cycles.