Controlled release of hydrogen from composite nanoparticles

A multi-functional nanoparticle for hydrogen storage or separation and controlled hydrogen release comprising:

• a plasmonic nanoparticle having a size of from about 1 nanometer to about 500 nanometers;
• and
• a nanosized particle having a size of from about 1 nanometer to about 100 nanometers deposited on a surface of the plasmonic nanoparticle and in thermal contact with the plasmonic nanoparticle, the nanosized particle comprising a reversible metal hydride that forms a first interstitial hydride with a first isotope of hydrogen and that forms a second interstitial hydride with a second isotope of hydrogen, wherein the first isotope of hydrogen is released from the first interstitial hydride at a first release condition and the second isotope of hydrogen is released from the second interstitial hydride at a second, different release condition.