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Usually, porous materials are synthesized by using conventional electric heating, which can be energy‐ and time‐consuming. Microwave heating is commonly used in many households to quickly heat food. Microwave ovens can also be used as powerful devices in the synthesis of various porous materials. The microwave‐assisted synthesis offers a simple, fast, efficient, and economic way to obtain many of the advanced nanomaterials. This review summarizes the recent achievements in the microwave‐assisted synthesis of diverse groups of nanoporous materials including silicas, carbons, metal–organic frameworks, and metal oxides. Microwave‐assisted methods afford highly porous materials with high specific surface areas (SSAs), e.g., activated carbons with SSA ≈3100 m2 g−1, metal–organic frameworks with SSA ≈4200 m2 g−1, covalent organic frameworks with SSA ≈2900 m2 g−1, and metal oxides with relatively small SSA ≈300 m2 g−1. These methods are also successfully implemented for the preparation of ordered mesoporous silicas and carbons as well as spherically shaped nanomaterials. Most of the nanoporous materials obtained under microwave irradiation show potential applications in gas adsorption, water treatment, catalysis, energy storage, and drug delivery, among others.

Ultrasounds are commonly used in medical imaging, solution homogenization, navigation, and ranging, but they are also a great energy source for chemical reactions. Sonochemistry uses ultrasounds and thus realizes one of the basic concepts of green chemistry, i.e., energy savings. Moreover, reduced reaction time, mostly using water as a solvent, and better product yields are among the many factors that make ultrasound-induced reactions greener than those performed under conventional conditions. Sonochemistry has been successfully implemented for the preparation of various materials; this review covers sonochemically synthesized nanoporous materials. For instance, sonochemical-assisted methods afforded ordered mesoporous silicas, spherical mesoporous silicas, periodic mesoporous organosilicas, various metal oxides, biomass-derived activated carbons, carbon nanotubes, diverse metal-organic frameworks, and covalent organic frameworks. Among these materials, highly porous samples have also been prepared, such as garlic peel-derived activated carbon with an apparent specific surface area of 3887 m2/g and MOF-177 with an SSA of 4898 m2/g. Additionally, many of them have been examined for practical usage in gas adsorption, water treatment, catalysis, and energy storage-related applications, yielding satisfactory results.

Highly porous activated carbons were synthesized via the mechanochemical salt-templating method using both sustainable precursors and sustainable chemical activators. Tannic acid is a polyphenolic compound derived from biomass, which, together with urea, can serve as a low-cost, environmentally friendly precursor for the preparation of efficient N-doped carbons. The use of various organic and inorganic salts as activating agents afforded carbons with diverse structural and physicochemical characteristics, e.g., their specific surface areas ranged from 1190 m2·g−1 to 3060 m2·g−1. Coupling the salt-templating method and chemical activation with potassium oxalate appeared to be an efficient strategy for the synthesis of a highly porous carbon with a specific surface area of 3060 m2·g−1, a large total pore volume of 3.07 cm3·g−1 and high H2 and CO2 adsorption capacities of 13.2 mmol·g−1 at −196 °C and 4.7 mmol·g−1 at 0 °C, respectively. The most microporous carbon from the series exhibited a CO2 uptake capacity as high as 6.4 mmol·g−1 at 1 bar and 0 °C. Moreover, these samples showed exceptionally high thermal stability. Such activated carbons obtained from readily available sustainable precursors and activators are attractive for several applications in adsorption and catalysis.

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