Network Topology of a Hybrid Organic Zinc Phosphate with Bimodal Porosity and Hydrogen Adsorption

摘要

In the last decade, the synthesis of nanoporous materials with extended network topologies has advanced extensively owing to the increasing demand for functional materials in applications involving molecular recognition, shape-selective catalysis, fluid separation, and hydrogen gas storage. Until now, two major categories of nanoporous structures have been under intense investigation: one with whole inorganic framework, such as silica-based zeolites, germanates, and phosphorous-based metal oxides; and another with organic-inorganic hybrid frameworks; that is, porous coordination polymers and metal-organic frameworks (MOFs). The largest pore and/or channel opening that has been observed in inorganic frameworks are 18-membered rings (18MR) in silicates, 24MR in metal phosphates, 26MR in metal phosphites, and 30MR in germanates. In the hybrid frameworks, however, the cavities were determined from pore structure analysis based upon gas sorption studies. By using bulky organic units to co-construct the framework, even higher porosity or larger pores can be produced. For example, the pore size found in the framework MIL-101 was up to 4.6 nm, and the void space in MOF-177 was reported to increase the size of a unit-cell volume by up to 81 %, thus substantially surpassing the volume of inorganic structures.