1 research outputs found
Enhanced Electrochemical Stability of a Zwitterionic-Polymer-Functionalized Electrode for Capacitive Deionization
In
capacitive deionization, the salt-adsorption capacity of the electrode
is critical for the efficient softening of brackish water. To improve
the water-deionization capacity, the carbon electrode surface is modified
with ion-exchange resins. Herein, we introduce the encapsulation of
zwitterionic polymers over activated carbon to provide a resistant
barrier that stabilizes the structure of electrode during electrochemical
performance and enhances the capacitive deionization efficiency. Compared
to conventional activated carbon, the surface-modified activated carbon
exhibits significantly enhanced capacitive deionization, with a salt
adsorption capacity of ∼2.0 × 10<sup>–4</sup> mg/mL
and a minimum conductivity of ∼43 μS/cm in the alkali-metal
ions solution. Encapsulating the activated-carbon surface increased
the number of ions adsorption sites and the surface area of the electrode,
which improved the charge separation and deionization efficiency.
In addition, the coating layer suppresses side reactions between the
electrode and electrolyte, thus providing a stable cyclability. Our
experimental findings suggest that the well-distributed coating layer
leads to a synergistic effect on the enhanced electrochemical performance.
In addition, density functional theory calculation reveals that a
favorable binding affinity exists between the alkali-metal ion and
zwitterionic polymer, which supports the preferable salt ions adsorption
on the coating layer. The results provide useful information for designing
more efficient capacitive-deionization electrodes that require high
electrochemical stability