Design and synthesis new anhydrous ionic conductors from metal-organic frameworks (MOFs) that are applicable at temperature higher than 100 oC to avoid the CO poisoning of Pt catalysts. The strategy is to encapsulate less volatile proton-carrier molecules in the pores of MOFs.
Metal-Organic Frameworks (MOFs)
Metal-organic framework (MOF), a class of compounds, is an infinite network of metal ions or metal ion clusters bridged by organic ligands to form a porous compound. MOFs are highly crystalline, which allows for ease in structural determination and tunability of components. The enormous potential structures can be obtained not only by the choice of metal and linker but also by the connectivity of the structure. So that, MOFs have received huge attention as promising porous materials for a wide range of applications including gas storage or separation, catalysis, drug delivery and as proton conducting membranes in hydrogen fuel cells.
Our interest is to synthesize new composite proton conducting membranes using MOFs.
Schematic of Metal-Organic Frameworks (MOFs)
Proton Exchange Membranes
Proton exchange membrane fuel cells (PEMFCs) are very promising as a replacement for traditional engines due to their high power PEMFCs, it would be ideal to operate the fuel cell over 100°C to avoid the CO poisoning of Pt catalysts at temperatures lower than 100 °C (CO from steam reforming to produce H2). Unfortunately, conventional PEM such as Nafion, which consists of a perfluorinated polyethylene backbone upon which are grafted side chains with terminal sulfonic acid groups, requires water as an integral part of the proton transfer chain in the membrane and its performance is limited by dehydration (~80°C). We aim to develop new solid electrolytes which are capable of conduction at 150°C in an anhydrous atmosphere using MOFs.
Schematic of Hydrated Nafion
MOFs as Proton Exchange Membranes
Schematic of hybridized proton conductor
The idea for making use of MOFs as proton exchange membranes is to encapsulate less volatile (compared to water) amphiprotic guest molecules in the pores of MOFs. We expect the proton conducting MOFs from this approach are capable of conduction at temperature higher than 150°C in an anhydrous. Previously, we successfully loaded imidazole into aluminium based MOF, [Al(OH)(1,4-ndc)]n (1,4-ndc = 1,4-naphthalene dicarboxylate). The conductivity of this system is 10-7 S cm-1 at 120°C with the activation energy of 0.9 eV. Design of better conducting materials based on these strategy is the basis of our ongoing work in this area.
- Bureekaew S., Horike S., Higuchi M.,Mizuno M., Kawamura T., Tanaka D., Yanai N., Kitagawa S., Nature Materials, 8, 831 - 836 (2009).
Dr. Sareeya Bureekaew (Lecturer)
Dr. Makoto Ogawa (Professor)
Dr. Chularat Wattanakit (Lecturer)
Dr. Kanokwan Kongpatpanich (Lecturer)
Dr. Sarawoot Impeng (Postdoctoral Research Fellow)
Ms. Thanadporn Tanasaro
Mr. Warat Pratanpornlerd
Ms. Wararat Tranganphaibul
Mr. Siwarut Siwaipram
International Research Collaborator:
Prof. Susumu Kitagawa Kyoto University, Japan
Prof. Masahiro Ehara Institute for Molecular Science, Japan