Mixed-dimensional nanocomposites based on 2D materials for hydrogen storage and CO2 capture

Porous materials possessing high surface areas are of paramount importance in gas separation and storage, as they can potentially adsorb a large amount of gas per unit of mass or volume. Pore structure and functionality are also important factors affecting adsorbate–absorbent interactions. Hence, efforts have been devoted to developing adsorbents with large accessible surface areas and tunable functionalities to realize improvements in gas adsorption capacity. However, the gas adsorption and storage capacities of porous materials composed of a single type of building unit are often limited. To this end, mixed-dimensional hybrid materials have been developed, as they can contain more gas storage sites within their structures than simple porous materials. In this review, we discuss (1) the methods that have been used to assemble various dimensional building blocks into a range of mixed-dimensional (zero-dimensional–two-dimensional, one-dimensional–two-dimensional, and three-dimensional–two-dimensional) hybrid materials exhibiting synergistic adsorption effects, and (2) these materials’ hydrogen and carbon dioxide adsorption properties and how they are correlated with their accessible surface areas. We conclude by outlining the challenges remaining to be surmounted to realize practical applications of mixed-dimensional hybrid materials and by providing future perspectives.