Improved Hydrogen Storage Properties of MgH₂ Co-Doped with FeCl₃ and Carbon Nanotubes

Abstract

A MgH2/FeCl3/carbon nanotubes (CNTs) composite was prepared by dry ball milling, and its hydrogen storage properties were investigated. The CNT addition resulted in both a decreased desorption temperature and improved sorption kinetics compared to the undoped MgH2–FeCl3 composite. The desorption temperature of the 5 wt % CNT-added MgH2–FeCl3 composite was decreased to 230 °C compared with 275 °C for undoped MgH2–FeCl3. For the dehydrogenation kinetics, the 5 wt % CNT-added MgH2–FeCl3 sample released about 4.3 wt % hydrogen at 320 °C after 4 min of dehydrogenation, while the MgH2–FeCl3 composite released about 3.1 wt % hydrogen under the same conditions. Meanwhile, for the rehydrogenation kinetics, the 5 wt % CNT-added MgH2–FeCl3 sample absorbed about 5.21 wt % hydrogen at 300 °C after 1 min of rehydrogenation, but the MgH2–FeCl3 composite only absorbed about 4.8 wt % hydrogen. The apparent activation energy, E a, for dehydrogenation decreased from 130 kJ/mol for the MgH2–FeCl3 composite to 112 kJ/mol by the addition of 5 wt % CNTs. It is believed that the enhancement of the hydrogenation performance of the MgH2/FeCl3/CNTs composite is due to the active Fe-containing species and the function of the Cl anions, as well as the unique structure of the CNTs.

Study on the hydrogen storage properties and reaction mechanism of NaAlH4–Mg(BH4)2 (2:1) with and without TiF3 additive

“…1). A similar phenomenon also appeared in the previous report on the different onset temperature between DSC and TPD result [38], these phenomenon happened may be due to the different condition of the dehydrogenation measurement conducted, as reported in our previous paper [39e42]. The TPD measurement was conducted from 0.1 atm vacuum with a 5 C/min heating rate; while the DSC measurement was run under 1 atm argon flow with heating rate of 20 C/min.…”

Constructing Core-Shell Co@N-Rich Carbon Additives Toward Enhanced Hydrogen Storage Performance of Magnesium Hydride

“…Based on the fitted slope of the Kissinger plot and the constant R, the activation energy E a is determined to be 116 ± 1.4 kJ mol −1 . The E a value of MgH 2 -5 wt% CoNC0 composites is comparable to the values for the materials reported previously, such as MgH 2 -10 wt% CoB/CNTs (119 kJ mol −1 ) (Gao et al, 2017), MgNCG (137 kJ mol −1 ) (Liu et al, 2016), MgH 2 -TiN (144 kJ mol −1 ) (Wang et al, 2015), and MgH 2 -FeCl 3 (130 kJ mol −1 ) (Ismail et al, 2014). These results further manifest the prominent effects of the Co@C additives on enhancing the dehydrogenation kinetics of pure MgH 2 .…”

Magnesium-Based Materials for Hydrogen Storage—A Scope Review

“…systems. Many studies have examined the influence of additives such as carbon nanotubes (CNTs), nanorods, graphene, and nanofibers [ 192 , 193 , 194 , 195 , 196 , 197 , 198 , 199 , 200 ]. All of this research has proven that mixed compounds of magnesium-based hydrides with catalysts and carbons influence the hydride synthesis outcome.…”