Engineering Framework Materials in Water Systems for Targeted Ion Extraction and Spontaneous Energy Harvesting.

Developing techniques that can extract required salt resources and harvest spontaneous energy from natural water environment is essential to promote the global decarbonization and electrification. Construction of advanced framework materials with intrinsic nanochannels has been considered the most promising solution to implement this technique owing to the specific fluid transport performances in such confined space. However, this design requires a deep understanding of the structural properties of framework material nanochannels in different scenarios, as well as the corresponding construction strategies. Consequently, it is an urgent necessity to elucidate the specific ion capture behavior and fluid transport mechanism in these framework materials to build targeted nanofluidic systems for guiding developments in water related resources and energy acquisition technologies. Herein, the recent advances in ion extraction and energy harvesting based on metal-organic framework and covalent-organic framework materials have been outlined, along with the discussion about the nanochannels specificity by combining ions and fluid properties and nanochannel structures. Finally, an outlook to trends, challenges and emerging opportunities is given to foresee the future developments in this important field.