Supported Metal Nanohydrides for Hydrogen Storage

Producción CientíficaAdsorption of hydrogen on graphdiyne (GDY) and boron-graphdiyne (BGDY) doped with palladium clusters has been investigated by performing density functional calculations. Pd6 fits well on the large holes of those porous layers, preserving its octahedral structure in GDY and changing it to a capped trigonal bipyramid structure in BGDY. Pd6GDY adsorbs up to five H2 molecules with sizable adsorption energies, two dissociated and three nondissociated. The dissociation barrier of H2 on the Pd6GDY cluster is 0.58 eV. Pd6BGDY can adsorb up to six molecules, three dissociated and three nondissociated, and the dissociation barrier of H2 on Pd6BGDY is 0.23 eV. In both cases, the dissociation barriers are substantially smaller than the corresponding dissociation barriers on undoped GDY and BGDY. The Pd clusters saturated with hydrogen can be viewed as nanohydrides. Spilling of the adsorbed hydrogen atoms toward the GDY and BGDY substrates is hindered by large activation barriers. We then propose using BGDY and GDY layers as support platforms for metal nanohydrides. The amount of stored hydrogen using Pd as the dopant is below the target of 6% of hydrogen in weight, but replacing Pd by a lighter metal with similar or higher affinity for hydrogen would substantially enhance the storage.Ministerio de Ciencia e Innovación (MCIN/AEI/ 10.13039/501100011033)(Grant PID2019-104924RB-I00

Adsorción de H2 sobre clusters de paladio soportados en una lámina de GDY

Estudios anteriores han demostrado que la funcionalización de Carbonos porosos y laminares con átomos metálicos mejoran su capacidad para adsorber Hidrógeno, atribuyendo esta mejora a un posible mecanismo de Spill-over en el cual el Hidrógeno inicialmente se adsorbe sobre el metal donde se disocia y posteriormente migra hacia el sustrato de Carbono. En este trabajo se ha estudiado, utilizando la Teoría del Funcional de la Densidad, la adsorción de Hidrógeno sobre clusters de Paladio (Pd1, Pd6) soportados sobre una lámina de Grafdiino. Dos casos fueron estudiados: la adsorción molecular y disociativa de H2. Los cálculos muestran que la adsorción de la molécula disociada es energéticamente más favorable respecto a la adsorción molecular, induciendo cambios estructurales en la geometría del cluster. Los resultados obtenidos sugieren que un mecanismo de Spill-over podría ocurrir.Previous works have shown that functionalization of porous and lamellar Carbons with metal atoms improves their ability to adsorb Hydrogen, attributing this improvement to a possible Spill-over mechanism in which Hydrogen initially is adsorbed on the metal where it dissociates and subsequently migrates towards the Carbon substrate. In this work we have studied, using the Density Functional Theory, the adsorption of Hydrogen on Palladium clusters (Pd1, Pd6) supported on graphdiyne layers. Two cases were studied: molecular and dissociative H2 adsorption . Calculations show that adsorption of the dissociative molecule is energetically more favorable with respect to molecular adsorption, inducing structural changes in the cluster geometry. The results obtained suggest that a Spill-over mechanism could occur.Departamento de Física Teórica, Atómica y ÓpticaMáster en Físic