Nanoporous Metal Oxides with Tunable and Nanocrystalline Frameworks via Conversion of Metal–Organic Frameworks

Nanoporous metal oxide materials
are ubiquitous in the material
sciences because of their numerous potential applications in various
areas, including adsorption, catalysis, energy conversion and storage,
optoelectronics, and drug delivery. While synthetic strategies for
the preparation of siliceous nanoporous materials are well-established,
nonsiliceous metal oxide-based nanoporous materials still present
challenges. Herein, we report a novel synthetic strategy that exploits
a metal–organic framework (MOF)-driven, self-templated route
toward nanoporous metal oxides via thermolysis under inert atmosphere.
In this approach, an aliphatic ligand-based MOF is thermally converted
to nanoporous metal oxides with highly nanocrystalline frameworks,
in which aliphatic ligands act as the self-templates that are afterward
evaporated to generate nanopores. We demonstrate this concept with
hierarchically nanoporous magnesia (MgO) and ceria (CeO2), which have potential applicability for adsorption, catalysis,
and energy storage. The pore size of these nanoporous metal oxides
can be readily tuned by simple control of experimental parameters.
Significantly, nanoporous MgO exhibits exceptional CO2 adsorption
capacity (9.2 wt %) under conditions mimicking flue gas. This MOF-driven
strategy can be expanded to other nanoporous monometallic and multimetallic
oxides with a multitude of potential applications.