The Improvement in Hydrogen Storage Performance of MgH2 Enabled by Multilayer Ti3C2

Abstract

MgH2 has become a hot spot in the research of hydrogen storage materials, due to its high theoretical hydrogen storage capacity. However, the poor kinetics and thermodynamic properties of hydrogen absorption and desorption seriously hinder the development of this material. Ti-based materials can lead to good effects in terms of reducing the temperature of MgH2 in hydrogen absorption and desorption. MXene is a novel two-dimensional transition metal carbide or carbonitride similar in structure to graphene. Ti3C2 is one of the earliest and most widely used MXenes. Single-layer Ti3C2 can only exist in solution; in comparison, multilayer Ti3C2 (ML-Ti3C2) also exists as a solid powder. Thus, ML-Ti3C2 can be easily composited with MgH2. The MgH2+ML-Ti3C2 composite hydrogen storage system was successfully synthesized by ball milling. The experimental results show that the initial desorption temperature of MgH2-6 wt.% ML-Ti3C2 is reduced to 142 °C with a capacity of 6.56 wt.%. The Ea of hydrogen desorption in the MgH2-6 wt.% ML-Ti3C2 hydrogen storage system is approximately 99 kJ/mol, which is 35.3% lower than that of pristine MgH2. The enhancement of kinetics in hydrogen absorption and desorption by ML-Ti3C2 can be attributed to two synergistic effects: one is that Ti facilitates the easier dissociation or recombination of hydrogen molecules, while the other is that electron transfer generated by multivalent Ti promotes the easier conversion of hydrogen. These findings help to guide the hydrogen storage properties of metal hydrides doped with MXene.

Positron Annihilation Spectroscopy Complex for Structural Defect Analysis in Metal–Hydrogen Systems

“…According to the results of a hydrogen release study from magnesium hydride, after 11 h in the chamber, one endothermic peak is observed, which corresponds to the release of hydrogen from the material. The beginning of hydrogen desorption from MgH 2 was observed at a temperature of 345 • C, and the peak temperature was about 380 • C. These results correlate with the data obtained in other works for milled magnesium hydride [46][47][48][49]. insulator transition during hydrogenation to the MgH2 phase [44].…”

Recent Development in Nanoconfined Hydrides for Energy Storage

“…Ongoing recent trends in developing novel systems for energy storage have incorporated MXene materials with a 2D structure, as promising hydride hosts [94,156,[176][177][178][179][180][181][182][183][184][185][186][187][188][189][190][191][192][193][194]. While only few examples are currently available, it is foreseeable that MXenes will grow to become a mainstream storage matrix for nanoconfined hydride-based materials (Table 7).…”

“…Due to its wide availability in nature, low cost, high gravimetric (7.6 wt.%) and volumetric (110 g/L) hydrogen storage capacities, the binary hydride, MgH 2 , is arguably the most studied metal hydride and Mg-based materials have been investigated exhaustively by a variety of research groups (Table 11) [34,43,47,53,55,57,61,65,77,78,80,92,94,95,98,102,103,109,110,115,118,121,122,124,130,134,137,146,147,149,158,[168][169][170]172,177,196,198,201,202,204,205,[208][209][210][211][212]…”

Catalytic characteristics of titanium‐( IV )‐isopropoxide ( TTIP ) on de/re‐hydrogenation of wet ball‐milled MgH 2 / Mg

“…16,33,[49][50][51] However, high-energy ball-milling is one of the most commonly used techniques to reduce the particle size of MgH 2 . 16,50,[52][53][54][55] This approach is significantly less expensive, with a high yield for synthesizing materials in the nano range than other approaches like chemical cold rolling and annealing. 56,57 The yield of materials depends on the milling parameters like milling intensity (rpm), the ball to material ratio, milling time, and the process control agent (medium: liquid or gas).…”

“…Various techniques explore the synthesis of catalyzed and uncatalyzed MgH 2 16,33,49‐51 . However, high‐energy ball‐milling is one of the most commonly used techniques to reduce the particle size of MgH 2 16,50,52‐55 . This approach is significantly less expensive, with a high yield for synthesizing materials in the nano range than other approaches like chemical cold rolling and annealing 56,57 .…”