Air-Stable Cu(I) Metal–Organic Framework for Hydrogen Storage
Debabrata Sengupta, Patrick Melix, Saptasree Bose, Joshua Duncan, Xingjie Wang, Mohammad Rasel Mian, Kent O. Kirlikovali, Faramarz Joodaki, Timur İslamoğlu, Taner Yildirim, Randall Q. Snurr, Omar K. Farha
Abstract
Metal–organic frameworks (MOFs) that contain open metal sites have the potential for storing hydrogen (H 2 ) at ambient temperatures. In particular, Cu(I)-based MOFs demonstrate very high isosteric heats of adsorption for hydrogen relative to other reported MOFs with open metal sites. However, most of these Cu(I)-based MOFs are not stable in ambient conditions since the Cu(I) species display sensitivity toward moisture and can rapidly oxidize in air. As a result, researchers have focused on the synthesis of new air-stable Cu(I)-based materials for H 2 storage. Here, we have developed a de novo synthetic strategy to generate a robust Cu(I)-based MOF, denoted as NU-2100, using a mixture of Cu/Zn precursors in which zinc acts as a catalyst to transform an intermediate MOF into NU-2100 without getting incorporated into the final MOF structure. NU-2100 is air-stable and displays one of the initial highest isosteric heats of adsorption (32 kJ/mol) with good hydrogen storage capability under ambient conditions (10.4 g/L, 233 K/100 bar to 296 K/5 bar). We further elucidated the H 2 storage performance of NU-2100 using a combination of spectroscopic analysis and computational modeling studies. Overall, this new synthetic route may enable the design of additional stable Cu(I)-MOFs for next-generation hydrogen storage adsorbents at ambient temperatures.