Sodium alanate nanoparticles--linking size to hydrogen storage properties

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Light metal hydrides like sodium alanate (NaAlH 4) are promising for hydrogen storage but suffer from slow kinetics and poor reversibility.
• Current methods like doping and ball-milling reduce particle size but have limitations.

Purpose of the Study:

• To investigate the effect of particle size on the hydrogen storage performance of sodium alanate (NaAlH 4).
• To synthesize carbon nanofiber-supported NaAlH 4 with controlled particle sizes.
• To establish a size-performance correlation for NaAlH 4 to guide future research.

Main Methods:

• Wet-chemical synthesis of carbon nanofiber-supported NaAlH 4.
• Preparation of NaAlH 4 with discrete particle size ranges: 1-10 microm, 19-30 nm, and 2-10 nm.
• Analysis of hydrogen desorption temperatures, activation energies, and reloading pressures.

Main Results:

• Hydrogen desorption temperatures decreased from 186°C (large particles) to 70°C (smallest particles).
• Activation energies for hydrogen desorption reduced from 116 kJ/mol to 58 kJ/mol with decreasing particle size.
• Smaller particle sizes of NaAlH 4 facilitated lower pressures for hydrogen reloading.

Conclusions:

• Particle size is a critical factor influencing the hydrogen storage performance of NaAlH 4.
• Controlled synthesis of nanostructured NaAlH 4 offers a viable route to enhance hydrogen storage kinetics and reversibility.
• The established size-performance correlation provides valuable insights for designing advanced nanostructured light metal hydrides for hydrogen storage applications.