Membrane
capacitive deionization (MCDI) has emerged as a promising
electric-field-driven technology for brackish water desalination and
specific salt or charged ion separation. The use of carbon-based or
pseudocapacitive materials alone for MCDI usually suffers from the
drawbacks of low desalination capacity and poor cycling stability
due to their limited accessible adsorption sites and obstructed charge-carrier
diffusion pathways. Therefore, developing a hybrid electrode material
with multiple charge storage mechanisms and continuous electron/ion
transport pathways that can synergistically improve its specific capacitance
and cycling durability has currently become one of the most critical
technical demands. Herein, we developed a novel hierarchically architectured
hybrid electrode by first spinning MXene into polyacrylonitrile (PAN)-based
carbon nanofibers (MCNFs) to obtain a highly conductive carbon nanocomposite
framework. The excellent spatial support structure can effectively
prevent the dense packing of Cl–- and DBS–-doped polypyrrole (PPy) molecular chains during the following electrodeposition
process, which not only ensures the efficient transport of electrons
in the continuous hybrid carbon nanofibrous skeleton but also provides
abundant accessible sites for ion adsorption and insertion. The obtained
self-supporting membrane electrodes (MCNF@PPy+Cl– and MCNF@PPy+DBS–) have the advantages
of outstanding specific capacitance (318.4 and 153.9 F/g, respectively),
low charge transfer resistance (10.0 and 5.3 Ω, respectively),
and excellent cycling performance (78% and 90% capacitance retention
ratios, respectively, after 250 electrochemical cycles). Furthermore,
the asymmetrical membrane electrodes showed a superior desalination
capacity of 91.2 mg g–1 in 500 mg/L NaCl aqueous
solution and obvious divalent ion (Ca2+, Mg2+) selective adsorption properties in high-salt water from the cooling
towers of thermal power plants.
With the rapid evolution of power and packing densities of microelectronic and energy storage devices, timely heat dissipation towards instantaneous high intensity heat flow is becoming increasingly significant to maintain...
Hierarchical macroporous TiO2/graphite-like
carbon hybrid
photocatalyts were successfully prepared by a facile method employing
a particle-stabilized high internal phase emulsion (Pickering emulsion)
as the template and sucrose as the carbon source. The results of this
study showed that mesopores, with diameters ranging from 10 to 50
nm, were homogeneously distributed on the cell-window structured macropore
walls that were armored by nano-sized TiO2 particles. Moreover,
a microporous graphitic layer of thickness ∼2 nm surrounded
the surface of the TiO2 particles. This type of hierarchical
macro-meso-microporous structure with high-efficiency diffusion and
mass transfer properties, along with the porous graphitic layers with
a high BET surface area, resulted in a hybrid catalyst possessing
high adsorption rate and capacity. In addition, the carbon layers
suppressed the transition temperature of titania (anatase to rutile)
by more than 200 °C. The green method presented here can potentially
be employed for the preparation of cost-effective environmental materials
toward the degradation of dyes and other pollutants.
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