Hydrogen from Ca-Mg Alloy Powders with Water at Room Temp

Key findings

• Adding 100 mL of water at room temperature (25 ℃) to 1 g of the alloy powder results in nearly complete hydrolysis and yields a high hydrogen output in a short time. After correcting for water vapor, the measured hydrogen volume corresponds to approximately 737–760 mL H₂ per gram of powder (produced within about 10 minutes).
• Raising the water temperature to 60 ℃ further increases both reaction rate and total yield, reaching up to ≈835 mL H₂/g (uncorrected value).
• Microstructural analysis using SEM/TEM/EDS shows that the gas-atomized powders are spherical (diameter ~6–65 µm), exhibit little oxidation, and contain a dense nanoscale dispersion of Ca-rich phases and Mg₂Ca phases. This fine-scale structure shortens water penetration paths and enables continuous hydrolysis reactions. (See Figures 1–2 in the full release.)

Comparison with other materials

Calcium metal flakes react rapidly but are difficult to control; MgH₂ tends to stop reacting due to formation of a dense Mg(OH)₂ surface layer. In contrast, the gas-atomized Ca–Mg eutectic powder balances high output, controllability, safety, and scalability of manufacture, making it an attractive candidate material for practical hydrogen generation.

Implications and future work

The powder is a promising material for portable hydrogen supply devices and emergency power units. Future work will investigate (1) the effect of using seawater instead of pure water, (2) stability and performance after long-term storage, and (3) safety measures and cost estimates for scale-up production.

Definitions

• Gas atomization: A process that converts molten metal into fine spherical particles by disintegrating a liquid metal stream with a high-speed gas flow and rapidly solidifying the resulting droplets.
• Hydrolysis (in this context): A chemical reaction in which the alloy reacts with water to cleave bonds and produce hydrogen as a reaction product.