Azobenzene modified metal-organic framework: For solar energy storage

A novel photochromic azo-grafted metal-organic framework (MOF), ZIF-90-AAT, was synthesized and characterized. ZIF-90-AAT not only retains the three-dimensional porous structure of ZIF-90 and high thermal stability, but also has sufficient free space for the isomerization reaction of azobenzene and photo-energy storage ability. ZIF-90-AAT displayed excellent reversible photochromic performance and can release photo-energy absorbed during the isomerization process. The result of differential scanning calorimetry (DSC) indicated that the energy storage density of ZIF-90-AAT is 5.796 J/g. In addition, ZIF-90-AAT also has the ability to melt broken ice during the isomerization-back process. This work demonstrated that MOFs can be used in the energy storage and expanded the application range of MOF materials.