hydrogenabsorbing

Hydrogen-absorbing refers to the ability of certain materials to take up hydrogen gas into their structure or chemical bonds. It includes reversible interstitial absorption in metals (metal hydrides), the formation of chemical hydrides, and physical adsorption in porous solids.

Mechanisms: In metals, hydrogen dissolves in interstitial lattice sites and can form metal hydrides such as MgH2 or TiH2. In complex hydrides, hydrogen is bound within covalent frameworks, as in alanates like NaAlH4. Some materials store hydrogen mainly by physisorption on high-surface-area solids such as activated carbon or porous metal-organic frameworks (MOFs).

Materials and applications: Metal hydrides are widely studied for hydrogen storage because they can release hydrogen at moderate temperatures and pressures. Magnesium hydride offers high capacity but often slow kinetics and high desorption temperature. Porous materials provide rapid uptake at low temperatures but typically lower storage capacity under ambient conditions.

Performance and challenges: Key metrics include storage capacity, operating conditions, absorption/desorption kinetics, reversibility over cycles, and material cost and safety. Practical systems require a balance between high storage density and favorable kinetics. Ongoing research seeks catalysts, improved reversibility, and safer, more durable hydrogen-absorbing materials.