title: First Evidence of Rh Nano-Hydride Formation at Low Pressure.
abstract: Rh-based nanoparticles supported on a porous carbon host were prepared with tunable average sizes ranging from 1.3 to 3.0 nm. Depending on the vacuum or hydrogen environment during thermal treatment, either Rh metal or hydride is formed at nanoscale, respectively. In contrast to bulk Rh that can form a hydride phase under 4 GPa pressure, the metallic Rh nanoparticles (∼2.3 nm) absorb hydrogen and form a hydride phase at pressure below 0.1 MPa, as evidenced by the presence of a plateau pressure in the pressure-composition isotherm curves at room temperature. Larger metal nanoparticles (∼3.0 nm) form only a solid solution with hydrogen under similar conditions. This suggests a nanoscale effect that drastically changes the Rh-H thermodynamics. The nanosized Rh hydride phase is stable at room temperature and only desorbs hydrogen above 175 °C. Within the present hydride particle size range (1.3-2.3 nm), the hydrogen desorption is size-dependent, as proven by different thermal analysis techniques.
authors.affiliation: Institut de Chimie et des Matériaux Paris-Est, CNRS UMR 7182, UPEC, 2-8, rue Henri Dunant, 94320 Thiais, France.
authors.forename: Claudia
authors.initials: C
authors.lastname: Zlotea
authors.affiliation: Institut de Chimie et des Matériaux Paris-Est, CNRS UMR 7182, UPEC, 2-8, rue Henri Dunant, 94320 Thiais, France.
authors.forename: Yassine
authors.initials: Y
authors.lastname: Oumellal
authors.affiliation: Institut de Chimie et des Matériaux Paris-Est, CNRS UMR 7182, UPEC, 2-8, rue Henri Dunant, 94320 Thiais, France.
authors.forename: Mariem
authors.initials: M
authors.lastname: Msakni
authors.affiliation: Institut de Chimie et des Matériaux Paris-Est, CNRS UMR 7182, UPEC, 2-8, rue Henri Dunant, 94320 Thiais, France.
authors.forename: Julie
authors.initials: J
authors.lastname: Bourgon
authors.affiliation: Institut de Chimie et des Matériaux Paris-Est, CNRS UMR 7182, UPEC, 2-8, rue Henri Dunant, 94320 Thiais, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Bastide
authors.affiliation: Institut de Chimie et des Matériaux Paris-Est, CNRS UMR 7182, UPEC, 2-8, rue Henri Dunant, 94320 Thiais, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Cachet-Vivier
authors.affiliation: Institut de Chimie et des Matériaux Paris-Est, CNRS UMR 7182, UPEC, 2-8, rue Henri Dunant, 94320 Thiais, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Latroche
keywords: Rh; hydride phase; hydrogen sorption; nanoparticles