Jiangying Qu

Self-templating synthesis of nitrogen-decorated hierarchical porous carbon from shrimp shell for supercapacitors

Nitrogen-doped hierarchical porous carbon (HPC) was prepared from shrimp shell using its intrinsic mineral scaffold (CaCO3) as the self-template combined with KOH activation. The roles of the template removal and KOH activation on the hierarchical porous structure of the obtained HPC were discussed in detail. The as-made HPC with abundant micropores, mesopores and interconnected macropores exhibits high electrochemical performance when used as the supercapacitor electrode. The specific surface area of HPC can be easily controlled via changing the activation temperature, and the natural nitrogen in shrimp shell can be preserved, which favor the final electrochemical property. Attributing to the synergetic electrochemical activity of the accessible porosity and the heteroatom, the hierarchical porous carbon pyrolyzed at 700 °C displays the largest specific capacitance of 348 F g−1 in a 6 M KOH electrolyte. The hierarchical porosity of the obtained carbon provides a well-defined ion pathway and electrolyte reservoir, allowing for rapid ionic transportation. This self-templating method represents a very attractive approach for the scalable production of hierarchical porous carbons from natural biomass containing both nitrogen/carbon sources and intrinsic templates.

Tailoring of three-dimensional carbon nanotube architectures by coupling capillarity-induced assembly with multiple CVD growth

We present a general method for the construction of 3D carbon nanotube (CNT) architectures with structural integrity and stability by the combination of capillary action and catalytic vapor-phase deposition (CVD). Using this method, patterned CNTs undergo the transformation from a vertically aligned structure to a hierarchically dual porosity material in a controllable way, which can be tuned by sequential modulation of the water-wetting and the CVD re-growth. By controlling the predesign of the substrate patterns, the CNT height, and the sequence of water wetting-CVD runs, diverse shapes and hybrid structures have been fabricated. This simple and versatile method might be extendable to the organization of other filamentary nanostructures for the construction of complex architectures made of various 1D building blocks.

Green fabrication of magnetic recoverable graphene/MnFe2O4 hybrids for efficient decomposition of methylene blue and the Mn/Fe redox synergetic mechanism

Herein, we report an environmentally benign synthesis of a high-performance reduced graphene oxide/MnFe2O4 (RGO/MnFe2O4) catalyst for methylene blue (MB) decomposition in neutral solution using a GO/MnSO4 suspension from a modified Hummers method and FeSO4 as the precursors. The as-prepared RGO/MnFe2O4 catalyst shows exceptional performance towards the MB decomposition in the presence of H2O2. In particular, 10 mL of MB (50 mg L−1) can be thoroughly decolorized in 130 min and 78% mineralized with 5 mg of RGO/MnFe2O4 hybrid at room temperature. More interestingly, the catalysts can be magnetically recycled. The good catalytic performance of the RGO/MnFe2O4 hybrid is not only attributed to the synergetic effects of RGO, MnFe2O4, H2O2 and MB molecules, but also related to the redox couples of Fe/Mn ions during the reaction. We have firstly experimentally demonstrated that the catalytic performance of MnFe2O4 is dominated by Fe3+/Fe2+ in the initial stage ( 70 min), while Fe2+/Mn3+ redox in turn benefits the redox cycles of Fe3+/Fe2+ and Mn3+/Mn2+. Our results not only provide an alternative strategy for green synthesis of high-performance functional nanomaterials, but also promote a deep understanding of the mechanism of MnFe2O4 catalyst for MB decomposition.

Fabrication, magnetic properties and self-assembly of hierarchical crystalline hexapod magnetites

We report a facile and surfactant-free solvothermal approach for the shape controlled synthesis of magnetite (Fe3O4). Hierarchical branched hexapod magnetites with various secondary structures can be prepared from ferrocene by using different solvents and tailoring experimental parameters. The as-prepared hexapods were characterized by X-ray diffraction, room temperature 57Fe Mossbauer spectroscopy, and scanning and transmission electron microscopy. Compared with bulk magnetite, the obtained Fe3O4 hexapods are single crystals and exhibit different ferrimagnetic behavior with relatively high specific saturation magnetization (90–128 emu g−1) and large coercivity (223–238 Oe) values depending on their size and morphology. Self-organization of the shape-anisotropic hexapod crystals has been achieved for the first time by evaporation-mediated assembly. The well-defined hexapod Fe3O4 crystals will be attractive as promising building blocks for the bottom-up design of advanced materials and devices which may have applications in many fields.

Carbon foams produced from lignin-phenol-formaldehyde resin for oil/water separation

Abstract Carbon foams for oil/water separation were synthesized using lignin-phenol-formaldehyde (LPF) resin as the carbon source and polyurethane (PU) foam as the template. Lignin was extracted from sedge grass and was used to replace 25 wt% of the phenol to prepare a LPF resin in an alkaline medium. The carbon foams exhibit unique properties such as open macropores, low bulk density, good water repellency and efficient oil absorption. The absorption capacities of the carbon foams are 12 to 41 times their own weight for a wide range of oils and organic solvents. The foams can be recycled by directly burning the oil within their pores and absorption capacity remains above 83% after 10 absorption test cycles, indicating that the carbon foams are promising oil sorbents with a good recyclability.