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Your search keyword '"Lei Wu"' showing total 2 results
2 results on '"Lei Wu"'

1. Deposition and transport of graphene oxide in saturated and unsaturated porous media

Author

Bin Gao, Lei Wu, Liuyan Yang, Verónica L. Morales, Lin Liu, Hao Wang, and Zuhao Zhou

Subjects
Work (thermodynamics), Chromatography, Materials science, Graphene, General Chemical Engineering, Oxide, General Chemistry, Interaction energy, Industrial and Manufacturing Engineering, law.invention, chemistry.chemical_compound, Chemical engineering, chemistry, law, Ionic strength, Environmental Chemistry, Deposition (phase transition), Porous medium, Water content
Abstract

In this work, sand and bubble column experiments were conducted to explore the deposition mechanisms of graphene oxide (GO) particles in porous media with various combinations of moisture content and ionic strength. Sand column experimental results indicated that retention and transport of GO in porous media were strongly dependent on solution ionic strength. Particularly, GO showed high mobility under low ionic strength conditions in both saturated and unsaturated porous media. Increasing ionic strength dramatically increased the retention of GO particles in porous media, mainly through secondary-minimum deposition as indicated in the XDLVO interaction energy profiles. Recovery rates of GO in unsaturated sand columns were lower than that in saturated columns under the same ionic strength conditions, suggesting moisture content also played an important role in the retention of GO in porous media. Findings from the bubble column experiments showed that the GO did not attach to the air–water interface, which is consistent with the XDLVO predictions. Additional retention mechanisms, such as film straining, thus could be responsible to the reduced mobility of GO in unsaturated porous media. The experimental data of GO transport through saturated and unsaturated porous media could be accurately simulated by an advection–dispersion-reaction model.

Published
2013

2. Polyaniline-assisted growth of MnO2 ultrathin nanosheets on graphene and porous graphene for asymmetric supercapacitor with enhanced energy density.

Author

Wang, Liang, Ouyang, Yu, Jiao, Xinyan, Xia, Xifeng, Lei, Wu, and Hao, Qingli

Subjects
*ANILINE derivatives, *MAGNESIUM oxide, *GRAPHENE, *THIN films, *ENERGY density, *SUPERCAPACITORS
Abstract

To enhance the energy density of supercapacitors, an asymmetric supercapacitor was prepared by well-matched graphene@MnO 2 nanosheets (G@MnO 2 ) as cathode material and porous graphene as anode material. The hierarchical MnO 2 ultrathin nanosheets uniformly decorating on graphene sheets were prepared by polyaniline-assisted growth method. The obtained G@MnO 2 composite can provide fast electron transfer rate and efficient space to decrease the length of ion diffusion during energy storage. Therefore, the G@MnO 2 electrode exhibits a high specific capacitance reaching 245.0 F g −1 at 0.5 A g −1 , 74.5% of retention ratio at 20 A g −1 . Meanwhile the assembled asymmetric supercapacitor delivers a high energy density of 30.6 W h kg −1 , and a remarkable energy density of 7.9 W h kg −1 at ultrahigh power density of 11,804 W kg −1 due to the well-assembly of G@MnO 2 and porous graphene with the similar capacitance and rate performance. Moreover, the asymmetric supercapacitor also shows an excellent cycle life with 8.5% loss of the initial specific capacitance after 10,000 cycles. The excellent electrochemical performance of the asymmetric supercapacitor of G@MnO 2 //porous graphene makes it an attractive candidate for high power and energy storage systems. [ABSTRACT FROM AUTHOR]

Published
2018
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