Haiou Song,Yifan Wu,Shupeng Zhang,Wentao Li,Baijun Wang,Changming Wang,Juanjuan Gao,Aimin Li
Capacitive deionization (CDI) is an emerging technology that supplies deionized water to resolve the fresh water shortage. CDI electrodes are mainly made up of carbon materials, of which the deionization performance is closely related to their physical properties and structures. Hence, a rational design of electrode material structure is essentially significant. Functionalized graphene (fG) in particular has recently been regarded as characteristic CDI electrode material. However, preparation of fG based on graphene oxide usually results in serious secondary pollution due to usage of highly poisonous chemicals, and thus still cannot meet the demand of practical application. It is feasible that environmentally-friendly activated carbon (AC) and small amounts of fGs can be combined rationally, and used as CDI electrodes. Here, sono-assembled AC/m-phenylenediamine (mPEA) or p-phenylenediaminefG inter-connected network architecture has been constructed for the first time successfully. The specific capacitances of the AC/fG composites were found to be significantly higher than that of the AC electrode owing to mesoporous generation. Also, among all the samples, the AC composite with 5 wt % mPEA-fG exhibited an ultrahigh electrosorption capacity of 12.58 mg/g (or 0.22 mmol/g) in NaCl solution. These observations indicate that fG can serve as an efficient conductive bridge to decrease the aggregation of AC particles, and improve the electron transfer with the composite electrode. This work provides an effective strategy for the environmental and economical electrode architectures for general applications in CDI and energy storage.
Graphical Dissolution-recrystallization strategy benefits both the porosity and Lewis acidity in Zr- β zeolite, which promotes catalytic conversion of ethanol-acetaldehyde. Zr based metallosilicalites, especially Zr- ß , is promising catalyst for the conversion of ethanol to 1,3-butadiene, which is considered to be a sustainable alternative to petroleum steam cracking. However it is suffering from deactivation derived from coking and unsatisfied catalytic activity derived from deficient Lewis acidity. For these issues, a dissolution-recrystallization process through tetraethyl ammonium hydroxide treatment (TEAOH) for enhancing porosity and Lewis acidity of Zr- ß zeolite was developed in this study. A balance of dissolution and recrystallization existed in this process, which was produced by OH − etching and templating of TEA + ions, creating additional mesoporosity. Zirconium active sites maintained tetrahedral coordination, while the Lewis acidity was enhanced by creating higher proportion open sites in framework. The recrystallized Zr- ß exhibited higher catalytic activity and stability in the conversion of ethanol-acetaldehyde to butadiene due to the compromise of microporosity and mesoporosity, as well as the appropriate enhancement of Lewis acidity.
Shoutian Qiu,Zhuo Li,Xiangyue Ye,Xiang Ying,Jiemei Zhou,Yong Wang
Block copolymers (BCPs) containing poly(dimethylsiloxane) (PDMS) blocks have been extensively used as precursors to prepare nanoporous materials with a diversity of compositions and morphologies. However, it remains desirable to facilely and efficiently transform the precursors into porous structures under mild conditions. Herein, we investigate the swelling behaviors of thin films of polystyrene-block-poly(dimethylsiloxane)-block-polystyrene (PS-b-PDMS-b-PS, SDS) in linear alkanes and produce well-defined nanoporosities in the SDS films following the mechanism of selective swelling-induced pore generation. Alkanes strongly swell PDMS blocks while slightly swell PS blocks, triggering the cavitation of the PDMS minority phases. The pore sizes as well as the porosities are determined by the interaction between the alkanes and the constituent blocks. Alkanes with lower carbon numbers exhibit a stronger affinity to the copolymer, leading to larger pores. Interestingly, we find that n-hexane is able to produce a porosity >30% at room temperature within a duration as short as 1 min. We demonstrate that PDMS, which has a lower surface energy, is enriched on the film surface, thus rendering a strong hydrophobicity to the produced porous SDS films. Ethanol permeation tests demonstrate the interconnected and accessible porosities and tunable flux as well as excellent pressure resistance of the porous SDS films, implying their potential applications as selective membranes in the filtration of organic solvents and oil/water separation.
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