The study of electrochemical hydrogen storage behavior of the MIL-53 (M=Cu, Al, Fe and Cr) framework on the Ag/f-MWCNTs substrate

Abstract

The goal of this study is to determine the effect of some metal on functionalized multi-walled carbon nanotubes (f-MWCNTs) as well as the impact of central metal on metal–organic frameworks, and the effect of both on the hydrogen storage performance. Another objective of the current study is to modify MOFs and introduce them to the carbonaceous materials. Through this technique which is based on the hydrogen “spillover effect”, the obtained nanocomposite witnessed a significant increase in hydrogen uptakes capacity as compared to the pristine samples. To this end, f-MWCNTs is designed with Cu2+, Ni2+, Co2+ and Ag+. According to the electrochemical hydrogen storage results, the best performance belongs to the Ag/f-MWCNTs which equals 1850 mAhg−1; this figure has increased more than 3.5 times as compared to the f-MWCNTs. Besides, MIL-53 (M=Cu, Al, Fe and Cr) is synthesized as important MOFs owing to their unique structural properties. Among these mentioned MOFs, the MIL-53(Cr) with the highest hydrogen storage capacity which equals 3100 mAhg−1, is selected to be combined with Ag/f-MWCNTs. Eventually, MIL-53(Cr)/Ag/f-MWCNTs nanocomposites, are prepared at ambient pressure and temperature. The hydrogen storage capacity of MIL-53(Cr)/Ag/f-MWCNTs is 4500 mAhg−1, which improved significantly at about 2.4 times higher than Ag/f-MWCNTs sample and 1.4 times higher than MIL-53(Cr) sample.