Novel and Versatile Cobalt Azobenzene‐Based Metal‐Organic Framework as Hydrogen Adsorbent

A novel URJC‐3 material based on cobalt and 5,5′‐(diazene‐1,2‐diyl)diisophthalate ligand, containing Lewis acid and basic sites, has been synthesized under solvothermal conditions. Compound URJC‐3, with polyhedral morphology, crystallizes in the tetragonal and P43212 space group, exhibiting a three‐dimensional structure with small channels along a and b axes. This material was fully characterized, and its hydrogen adsorption properties were estimated for a wide range of temperatures (77–298 K) and pressures (1–170 bar). The hydrogen storage capacity of URJC‐3 is quite high in relation to its moderate surface area, which is probably due to the confinement effect of hydrogen molecules inside its reduced pores of 6 Å, which is close the ionic radii of hydrogen molecules. The storage capacity of this material is not only higher than that of active carbon and purified single‐walled carbon nanotubes, but also surpasses the gravimetric hydrogen uptake of most MOF materials. Storing H2: A newly synthesized URJC‐3 material based on cobalt and a 5,5′‐(diazene‐1,2‐diyl)diisophthalate ligand exhibits a relatively high hydrogen storage capacity, especially in relation to its moderate surface area. This property probably relates to confinement of H2 inside the pores, which are close in size to the ionic radius of hydrogen molecules.