▎ 摘　　要

NOVELTY - Composite catalyst comprises: (a) a main catalyst comprising iron, cobalt, nickel, molybdenum and/or tungsten; (b) a promotion catalyst comprising platinum, palladium, ruthenium, rhodium, gold and/or silver; and (c) a support comprising either a transition metal oxide support or (ii) a support based on a combination of alumina and/or silica with a carbon-based support comprising activated carbon and/or graphene or (iii) a combination of (i) with at least one of alumina, silica, activated carbon and graphene. USE - The composite catalyst is useful: for catalyzing the hydrogenation of an organic hydrogen energy storage material; for catalyzing the dehydrogenation of an organic hydrogen energy storage material; and for catalyzing both the hydrogenation and dehydrogenation of an HESM; and in a hydrogen storage system or device, which is in the form of an energy storage device, a battery, electrocatalysis or photocatalysis equipment or a sensor (all claimed). ADVANTAGE - The composite catalyst: is capable of catalyzing the hydrogenation of an organic hydrogen energy storage material (HESM); is capable of catalyzing the hydrogenation of an HESM at a pressure of below 8 MPa and a temperature of below 250 degrees C; is capable of catalyzing the dehydrogenation of a fully hydrogenated HESM; is capable of catalyzing the dehydrogenation of a fully hydrogenated HESM at a temperature of below 300 degrees C or below 250 degrees C; achieves a conversion rate of at least 90%, preferably 100% the HESM; achieves selectivity for full hydrogenation of an HESM containing more than one double bond of at least 80%, preferably 100%; achieves a hydrogen unloading rate of at least 85%, preferably 100%; achieves selectivity for full dehydrogenation of an HESM containing more than one double bond of at least 80%, preferably 100%; exhibits higher efficiency and/or catalyst-poisoning resistance; provides excellent potential for commercial applications in the field of hydrogen energy storage and conversion; is cheap, non-precious metals and easily processed, facilitating industrial manufacturing; provides a potential to lower the price of hydrogen energy application; enables quick dissociation of hydrogen molecules into hydrogen atoms, thus enhancing the efficiency of the main catalyst on the hydrogenation and dehydrogenation reactions; has an interaction with the catalysts; and is economical. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for (a1) the storing and subsequent releasing hydrogen comprising contacting hydrogen with an organic hydrogen energy storage material (HESM) under hydrogenation conditions in the presence of a composite catalyst to convert the HESM into a hydrogenated HESM and then (a2) contacting the hydrogenated HESM with a composite catalyst under dehydrogenation conditions to release hydrogen from the hydrogenated HESM.