Zeolite-templated
carbons (ZTCs) are a distinct class of porous
framework materials in which a three-dimensional network of pores
is contained between atomically thin, polycyclic hydrocarbon walls,
synthesized by carbonization within a zeolite template. This class
of materials arose from the goal to develop carbon-based frameworks
with ordered, homogeneous microporosity (as opposed to activated carbons
where the pore network is random). It has more recently been suggested
that zeolite-templating may be a viable synthetic route to carbon
schwarzites, an elusive class of theoretical materials with a triply
periodic minimal surface and many fundamentally interesting properties.
In this review, we survey the currently proposed atomistic models
of ZTCs, compare them to experimental properties of ZTCs, and emphasize
the significant differences that remain between actual ZTCs prepared
in the laboratory and the still elusive schwarzites.
The
addition of redox-active molecules into electrochemical-capacitor
electrolytes provides increased specific energy density. Here we illustrate
the underlying operational mechanisms and design principles for carbons
with hierarchical pore sizes in the micropore (0.6–2 nm) to
mesopore (2–3 nm, 5–30 nm) range as electrode materials
in redox-enhanced electrochemical capacitors. When using iodide as
a model redox additive, we discover that the redox capacity is correlated
to the pore volume of the carbon electrodes when void space is included.
The fastest rates are typically observed with pore-sizes >1 nm,
while
slow self-discharge requires pores <1 nm. When used without an
ion-selective-membrane separator, the delivered capacity correlated
with the quantity of redox species held within the carbon. A commercial
microporous carbon, MSC30, with substantial hierarchy in pore size,
including small <0.8 nm pores and larger 1.1–3 nm pores,
showed the best overall performance, illustrating key design principles.
High-density and highly porous graphene-based pellets with anomalous gas densification property have been fabricated by using zeolite-templated carbon (ZTC) as the major component and reduced graphene oxide (rGO) as a...
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