Papers by Author: Wei Xing

Abstract: Highly porous carbons were prepared from sunflower seed shell (SSS) by chemical activation and used as electrode material for electrochemical double layer capacitor (EDLC). The surface area and pore structure of the porous carbons are characterized intensively using N₂ adsorption technique. The results show that the pore-structure of the carbons is closely related to activation temperature. Electrochemical measurements show that the carbons have excellent capacitive behavior and high capacitance retention ratio at high drain current, which is due to that there are both abundant macroscopic pores and micropore surface in the texture of the carbons. More importantly, the capacitive performances of these carbons are much better than ordered mesoporous carbons, thus highlighting the success of preparing high performance electrode material for EDLC from SSS.

Abstract: Ordered Mesoporous Silica with Uniform Pore Size Was Prepared by Using Pluronic P123 as the Structure-Directing Agent. their Characteristics Were Analysized by TEM and a N₂ Adsorption System. Ionic Liquid-Based Gel Electrolyte Was Fabricated by Using Ordered Mesoporous Silica as the Framework Materials to Solidify Ionic Liquid Electrolyte. the Diffusion Coefficient of I₃^- in Gel Electrolyte Is Higher than that in Ionic Liquid Electrolyte due to the Formation of Favorable Channel for I₃^- Diffusion. the Optimized Overall Conversion Efficiency of Dye-Sensitized Solar Cells with Ionic Liquid-Based Gel Electrolyte Was 5.22% under Irradiation of 60 MW Cm^-2.

Abstract: Hierarchical porous carbons (HPC) were synthesized by a combination of self-assembly and chemical activation method. A mesoporous carbon with large-size pore was used as raw materials. N₂ sorption measurement indicated that plenty of micropores generated within the mesopore wall in the mesoporous carbon during KOH activation. Electrochemical impedance spectroscopy measurement demonstrated a high electrocatalytic activity of HPC electrode for triiodide reduction. The overall conversion efficiency of dye-sensitized solar cells with HPC counter electrode was 6.48%, which is similar to that of the device with conventional Pt counter electrode.

Abstract: Arrays of ordered carbon nanotubes (OCNT) was synthesized successfully using aluminated mesoporous silica as hard template. XRD tests and TEM observations showed that OCNT was composed of carbon nanotube arrays in p6mm symmetry. N₂ sorption analyses demonstrated that OCNT possesses typical mesoporous structure and centralized mesopore distribution. OCNT are superior to Maxsorb, an active carbon with super high surface area, in capacitive behavior and power output due to their ordered pore-structure, which favors the fast diffusion of hydrated ions. As evidenced by cyclic voltammetry measurements, OCNT show good capacitive behaviors (exhibiting a high capacitance of 180 F/g even at very high sweep rate of 50 mV/s, as compared with much reduced capacitance of 73 F/g for Maxsorb at the same sweep rate). OCNT can provide very high power density while still maintaining good energy density, thus having potential uses in electrochemical double layer capacitor (EDLC), particularly where both high power output and energy density are required.

Abstract: Nanoporous carbons were prepared from rice husk (RH) according to a three-step procedure that includes pre-carbonization, silica removal and chemical activation. The surface area and pore structure of the nanoporous carbons are characterized intensively using N₂ adsorption technique. The as-prepared carbons have specific surface area of up to 3283 m²/g, and total pore volume of up to 1.8 cm³/g. The effect of activating agent dosage on the pore structure of carbons was investigated and elucidated clearly. As evidenced by electrochemical measurements, the as-prepared carbons have good capacitive performances and their specific capacitances are much higher than ordered mesoporous carbon, thus highlighting the success of preparing high performance electrode material for EDLC from a biomass waste, rice husk.