Subscriber access provided by NEW YORK UNIV
Communication
A Water Stable Magnesium MOF that Conducts Protons over 10-2 Scm-1 Padmini Ramaswamy, Norman E. Wong, Benjamin S. Gelfand, and George K. H. Shimizu J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/jacs.5b04399 • Publication Date (Web): 08 Jun 2015 Downloaded from http://pubs.acs.org on June 10, 2015
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
Journal of the American Chemical Society is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 5
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Journal of the American Chemical Society
A Water Stable Magnesium MOF that Conducts Protons over 10-2 Scm-1 Padmini Ramaswamy, Norman E. Wong, Benjamin S. Gelfand and George K. H. Shimizu* Department Of Chemistry, University Of Calgary, Calgary, Alberta T2N 1N4, Canada
Supporting Information ABSTRACT: From the outset of the study of MOFs as proton conductors, both conductivity and hydrolytic robustness of the materials have needed to be improved. Here, we report a layered magnesium carboxyphosphonate framework, PCMOF10, that shows an extremely high proton conductivity -2 -1 value of 3.55 x 10 S·cm at 70°C and 95%RH. Moreover, PCMOF10 is water stable owing to strong Mg phosphonate bonding. The 2,5- dicarboxy-1,4-benzenediphosphonic acid (H6L) linker anchors a robust backbone and has hydrogen phosphonate groups that interact with the lattice water to form an efficient proton transfer pathway.
Growing global energy demands require research efforts aimed at the discovery and development of alternative ener1 gy technologies. Fuel cell technology is a key part of present 2 and future opportunities. Better electrolyte materials are critical to enhancing cost efficiency of fuel cells. With regard to research on potential electrolyte materials, a wide variety 3 of compounds such as ceramic oxides and hydroxides, oxo4 5 6 acids, polymers, carbon nanotubes, and their blends and/or adducts have been investigated as proton conductors.
While the crystallinity of PCMOFs enables their use as model for developing structure activity relationships in proton conductors, the promise of genuine applicability has typically required both higher values of proton conductivity and also more robust networks than reported for PCMOFs to date. A decade ago, the robustness issue could be generalized to MOF materials but significant advances in this regard 13 14,15b including for PCMOFs. have been made since then There have also been steadily increasing values of proton conduction in MOFs reported and there are now a handful of materials that give proton conduction values in excess of the -2 -1 10 S·cm benchmark, albeit typically in a less robust frame15a work. Here, we report a proton-conducting MOF, (H6L=2,5-dicarboxy-1,4-benzeneMg2(H2O)4(H2L).H2O diphosphonic acid), PCMOF10, that merges water stability and high proton conduction. PCMOF10 is a new material with a robust layered structure that conducts protons at 3.55
Metal-organic frameworks (MOFs) have emerged as novel 7,8 proton conducting materials. The crystallinity and tunability of MOFs offer a convenient platform to design materials for targeted applications. While gas permeability is a detriment to a fuel cell membrane, the micropores in MOFs can be used to advantage by loading them with proton carriers such as water or a less volatile species. Furthermore, the precise pore structure and even location of guest carriers in a MOF can be visualized creating a useful handhold for modeling proton conduction in solids. MOFs can be fabricated into 9 thin films, and incorporated into mixed-matrix membranes 10 thus increasing their viability in industrial applications. Proton-conducting MOFs (PCMOFs) broadly fall under two categories - those of interest for operation under lowtemperature (
