H storage in solid materials


Nowadays, global warming is undeniable, requiring new and innovative technologies to limit the emissions of greenhouse gases. Hydrogen is a promising and sustainable candidate for this purpose. It is one of the most abundant elements on Earth and is expected to play a major role in the next technological revolution by powering the next generation of vehicles. For example, 24 kg of gasoline is required for a modern combustion-engine car to travel 400 km, whereas the same distance can be covered using only 8 kg of hydrogen. Additionally, the engine only emits water vapor as a byproduct. Therefore, intense research is ongoing to improve hydrogen storage in order to address the challenge of global warming.

Volume of 4 kg of hydrogen compacted in different ways, with size relative to the size of a car (Sflapbach et al. Nature, 2001).

However, the use of hydrogen remains challenging because it needs to be stored onboard safely and compactly at room temperature. The tragic crash of the Zippelin-Hindenburg in 1937 serves as a reminder of the dangers. The first approach, already used in current hydrogen vehicles, is to store the hydrogen in its gas or liquid state. Such methods require extremely expensive tanks that can withstand both high pressure and very low temperatures in order to limit evaporation. Therefore, these solutions are not compatible with daily life and safety requirements.

A promising route for hydrogen storage is the use of solid materials that can reversibly store hydrogen using metastable hydrides. This method enables absorption and desorption mechanisms, and eliminates the limitations imposed by pressurized tanks, and drastically reduces the weight of the vehicle. However, there is a poor understanding of the effects of structural defects and catalysts on the physical mechanisms of the reaction due to numerous constraints.

Ongoing project on the H storage

2020–2023: Thesis of Adrien HEINZELMEIER
Absorption/desorption of hydrogen in MAX phases, MXenes and their Mg-based nanocomposites.