Herein, the synergistic effects of
hollow nanoarchitecture and
high specific surface area of hollow activated carbons (HACs) are
reported with the superior supercapacitor (SC) and capacitive deionization
(CDI) performance. The center of zeolite imidazolate framework-8 (ZIF-8)
is selectively etched to create a hollow cavity as a macropore, and
the resulting hollow ZIF-8 (HZIF-8) is carbonized to obtain hollow
carbon (HC). The distribution of nanopores is, subsequently, optimized
by KOH activation to create more nanopores and significantly increase
specific surface area. Indeed, as-prepared hollow activated carbons
(HACs) show significant improvement not only in the maximum specific
capacitance and desalination capacity but also capacitance retention
and mean desalination rates in SC and CDI, respectively. As a result,
it is confirmed that well-designed nanoarchitecture and porosity are
required to allow efficient diffusion and maximum electrosorption
of electrolyte ions.