title: Facile synthesis of hydroxy-modified MOF-5 for improving the adsorption capacity of hydrogen by lithium doping.
abstract: A facile synthesis of partially hydroxy-modified MOF-5 and its improved H2-adsorption capacity by lithium doping are reported. The reaction of Zn(NO3)2·6H2O with a mixture of terephthalic acid (H2BDC) and 2-hydroxyterephthalic acid (H2BDC-OH) in DMF gave hydroxy-modified MOF-5 (MOF-5-OH-x), in which the molar fraction (x) of BDC-OH(2-) was up to 0.54 of the whole ligand. The MOF-5-OH-x frameworks had high BET surface areas (about 3300 m(2) g(-1)), which were comparable to that of MOF-5. We suggest that the MOF-5-OH-x frameworks are formed by the secondary growth of BDC(2-)-rich MOF-5 seed crystals, which are nucleated during the early stage of the reaction. Subsequent Li doping into MOF-5-OH-x results in increased H2 uptake at 77 K and 0.1 MPa from 1.23 to 1.39 wt.% and an increased isosteric heat of H2 adsorption from 5.1-4.2 kJ mol(-1) to 5.5-4.4 kJ mol(-1).
authors.affiliation: Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan), Fax: (+81) 3-3800-3806; Current address: Department of Chemical Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi Hiroshima, Hiroshima 739-8527 (Japan).
authors.forename: Masaru
authors.initials: M
authors.lastname: Kubo
authors.forename: Hayato
authors.initials: H
authors.lastname: Hagi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Shimojima
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Okubo
keywords: adsorption; doping; hydrogen; lithium; metal-organic frameworks