Hydrogen Storage in the Dehydrated Prussian Blue Analogues M_3[Co(CN)_6]_2 (M = Mn, Fe, Co, Ni, Cu, Zn)

摘要

Owing to its clean combustion and high heating value, hydrogen is under consideration as a replacement for fossil fuels in mobile applications. Its success in this role, however, relies in part upon development of an effective means of storage. Although extensive effort has been directed toward storing hydrogen in nanostructured carbon, chemical hydrides, and metal hydrides, such materials still exhibit limitations necessitating further research. Recently, Yaghi and co-workers exposed the considerable potential for hydrogen storage in microporous coordination solids with robust three-dimensional frameworks and high surface areas. Specifically, cubic frameworks consisting of tetrahedral [Zn_4O]~(6+) units linked via linear aryldicarboxylates were shown to adsorb significant quantities of hydrogen reversibly, with Zn_4O(BDC)_3 (BDC = 1,4-benzenedi-carboxylate) adsorbing 1.3 wt % H_2 at 77 K and 1 atm. This work was followed by reports of hydrogen storage in several different porous frameworks, most of which also contain aryldicarboxylates as the organic linker. In such compounds, the primary interaction with hydrogen is thought to be through van der Waals contact with the framework. Here, we report the hydrogen storage properties for dehydrated Prussian blue analogues of the type M_3[Co(CN)_6]_2, wherein interactions with bridging cyanide ligands and/or coordi-natively unsaturated metal centers lead to higher adsorption enthalpies.