Photoswitching metal organic frameworks development and applications on environmental related topics

Environmental related issues such as global warming, water pollution, and waste production are becoming ever-more urgent and are endangering the lives of human beings. The development of new functional materials for tackling such environmental issues is still an ongoing process. Photoswitching metal organic frameworks (MOFs), as a crystalline, hybrid porous material, have been widely reported in environmental-related topics such as greenhouse gas storage and hazard removals. Through integration with photochromic units, MOFs are endowed with photoswitchable ability upon remote light control. Such capability can greatly save the energy cost for MOF adsorbents regeneration via abundant renewable light resource triggering. Therefore, photoswitching MOFs are wildly researched and applied in remote-controlled capture and release of various gases (carbon dioxide [CO₂], methane [CH₄], acetylene [C₂H₂]), organic dyes, other hazardous chemicals, and even toxic metals. Apart from that, in the form of films, these smart MOFs membranes have also been used for molecular mixtures separation. Thus, photoswitching MOFs have strong potentials to tackle current environmental problems such as greenhouse emissions and hazard pollution. In this review, the fabrication method, different wavelengths of light-triggered photoswitching MOFs, and the environmental-related applications are summarized. As for applications, controllable CO₂ capture via photoswitching MOF powders or films is mostly reported. Moreover, the mechanism of light-triggered CO₂ switching was discussed in this review.