N-Doped Graphene-Rich Aerogels Decorated with Nickel and Cobalt Nanoparticles: Effect on Hydrogen Storage Properties of Nanoconfined LiBH 4

GASNIER, AURELIEN; AMICA, GUILLERMINA; JUAN, JULIÁN; TROIANI, HORACIO; GENNARI, FABIANA C.

JOURNAL OF PHYSICAL CHEMISTRY C

AMER CHEMICAL SOC

Lugar: Washington; Año: 2019 vol. 124 p. 115 - 125

1932-7447

We present the decoration of N-doped graphene entangled inmesoporous carbon by nickel and/or cobalt nanoparticles. The textural properties ofthe mesoporous materials were characterized by nitrogen desorption isotherms. Thematerials presented metallic nanoparticles of at least 20 nm and diffraction peaks typicalof cubic cobalt or nickel. Transmission microscopy revealed the presence of graphenelayers, organized mostly in an onionlike fashion around the metallic nanoparticles,suggesting that these might promote the formation of extra graphene sheets from thesurrounding amorphous carbon. The formation of a metallic alloy when nickel andcobalt were mixed is strongly suggested. Differential scanning calorimetry of thesematerials filled with LiBH4 demonstrated that the presence of nanoparticles displacedthe typical transition, melting, and decomposition peaks of this hydride toward lower temperatures. Volumetric studies revealedthat the liberation of hydrogen started at lower temperatures when nanoparticles were present, slowing down at highertemperatures. Cobalt-decorated materials liberated 8 wt % H2 at 325 °C during the first cycle (with 1 wt % released at 226 °C).After rehydrogenation at 400 °C, the materials decorated with nickel liberated 8 wt % H2, a 2 wt % excess compared to that ofthe nondecorated materials.