Light-Activated Hydrogen Storage in Mg, LiH and NaAlH4

The concept of light activation for triggering hydrogen release or uptake in hydrogen storage materials was investigated with the aid of gold (Au) nanoparticles dispersed at the surface of typical hydrides including magnesium hydride (MgH2), lithium hydride (LiH) and sodium alanate (NaAlH4). Upon Xe lamp illumination, the overall temperature of the materials reached ca. 100 degrees C owing to the plasmonic heating effect of the Au nanoparticles. Direct-heat-driven hydrogen storage at the same temperature with a conventional electrical furnace was found to be less effective with a smaller fraction of hydrogen released from Au/LiH and no phase conversion for Au/NaAlH4 or for Au/Mg under hydrogen pressure. The better efficiency of the observed light-driven hydrogen storage is attributed to the higher temperature in the vicinity of the Au nanoparticles owing to their plasmonic effect. With further improvements, light-activated hydrogen storage could lead to an effective approach for hydrogen uptake and release from hydrides at low temperatures.