A comprehensive review of the recent progress in the applications of hierarchically structured porous materials is given.

Owing to their immense potential in energy conversion and storage, catalysis, photocatalysis, adsorption, separation and life science applications, significant interest has been devoted to the design and synthesis of hierarchically porous materials. The hierarchy of materials on porosity, structural, morphological, and component levels is key for high performance in all kinds of applications. Synthesis and applications of hierarchically structured porous materials have become a rapidly evolving field of current interest. A large series of synthesis methods have been developed. This review addresses recent advances made in studies of this topic. After identifying the advantages and problems of natural hierarchically porous materials, synthetic hierarchically porous materials are presented. The synthesis strategies used to prepare hierarchically porous materials are first introduced and the features of synthesis and the resulting structures are presented using a series of examples. These involve templating methods (surfactant templating, nanocasting, macroporous polymer templating, colloidal crystal templating and bioinspired process, i.e. biotemplating), conventional techniques (supercritical fluids, emulsion, freeze-drying, breath figures, selective leaching, phase separation, zeolitization process, and replication) and basic methods (sol–gel controlling and post-treatment), as well as self-formation phenomenon of porous hierarchy. A series of detailed examples are given to show methods for the synthesis of hierarchically porous structures with various chemical compositions (dual porosities: micro–micropores, micro–mesopores, micro–macropores, meso–mesopores, meso–macropores, multiple porosities: micro–meso–macropores and meso–meso–macropores). We hope that this review will be helpful for those entering the field and also for those in the field who want quick access to helpful reference information about the synthesis of new hierarchically porous materials and methods to control their structure and morphology.

Oxygen self-doped CNO- x with tunable electronic band structure demonstrates unprecedentedly enhanced photodegradation of RhB and photocatalytic H ₂ production with excellent stability under visible light.

The lithium–selenium (Li–Se) battery has attracted growing interest recently due to its high energy density and theoretical capacity. However, the shuttle effect and volume change during cycling severely hinder its further application. In this work, we report a metal–organic framework (MOF)-derived nitrogen-doped core–shell hierarchical porous carbon (N-CSHPC) with interconnected meso/micropores to effectively confine Se for high-performance Li–Se batteries. The micropores were located at the ZIF-8-derived core and the ZIF-67-derived shell, while mesopores appeared at the core–shell interface after the pyrolysis of the core–shell ZIF-8@ZIF-67 precursor. Such a special hierarchical porous structure effectively confined selenium and polyselenides to prevent their dissolution from the pores and also alleviated the volume change. In particular, in situ nitrogen doping, which afforded N-CSHPC, not only improved the electrical conductivity of Se but also provided strong chemical adsorption on Li₂Se, as confirmed by density functional theory calculations. On the basis of dual-physical confinement and strong chemisorption, Se/N-CSHPC-II (molar ratio of Co source to Zn source of 1.0 in the core–shell ZIF-8@ZIF-67 precursor) exhibited reversible capacities of up to 555 mA h g⁻¹ after 150 cycles at 0.2 C and 462 mA h g⁻¹ after 200 cycles at 0.5 C and even a discharge capacity of 432 mA h g⁻¹ after 200 cycles at 1 C. Our demonstration here suggests that the carefully designed Se/C composite can improve the reversible capacity and cycling stability of Se cathodes for Li–Se batteries.