Ordered Macro-Microporous Metal-Organic Framework Single Crystals and Their Derivatives for Rechargeable Aluminum-Ion...

Constructing ordered hierarchical porous structures while maintaining their overall crystalline order is highly desirable but remains an arduous challenge. Herein, we successfully achieve the growth of single-crystalline metal-organic frameworks (MOFs) in three-dimensional (3D) ordered macroporous template voids by a saturated solution-based double-solvent-assisted strategy with precise control over the nucleation process. The as-prepared single-crystalline ordered macro-microporous Co-based MOFs (SOM ZIF-67) exhibit an ordered macro-microporous structure with robust single-crystalline nature. Moreover, SOM ZIF-67 can serve as a precursor to derive 3D-ordered macroporous cobalt diselenide@carbon (3DOM CoSe₂@C) through a facile carbonization-selenization treatment. The as-derived 3DOM CoSe₂@C can well preserve the 3D-ordered macroporous structure of the precursor. More importantly, CoSe₂ nanoparticles could be uniformly confined in the conductive ordered macroporous carbon framework, affording regularly interconnected macroporous channels and large surface area. As a result, when evaluated as a cathode material for aluminum-ion batteries, the ordered macroporous structure could not only effectively facilitate the diffusion of large-sized chloroaluminate anions but also increase the contact area with electrolyte and provide more exposed active sites, thereby exhibiting superior reversible rate capacity (86 mA h g^-1 at 5.0 A g^-1) and remarkable cycling performance (125 mA h g^-1 after 1000 cycles at 2.0 A g^-1).