First Evidence of Rh Nano-Hydride Formation at Low Pressure

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• 作者：Claudia Zlotea ; Yassine Oumellal ; Mariem Msakni ; Julie Bourgon ; St茅phane Bastide ; Christine Cachet-Vivier ; Michel Latroche
• 刊名：Nano Letters
• 出版年：2015
• 出版时间：July 8, 2015
• 年：2015
• 卷：15
• 期：7
• 页码：4752-4757
• 全文大小：357K
• ISSN：1530-6992

文摘

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 (鈭?.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鈥揷omposition isotherm curves at room temperature. Larger metal nanoparticles (鈭?.0 nm) form only a solid solution with hydrogen under similar conditions. This suggests a nanoscale effect that drastically changes the Rh鈥揌 thermodynamics. The nanosized Rh hydride phase is stable at room temperature and only desorbs hydrogen above 175 掳C. Within the present hydride particle size range (1.3鈥?.3 nm), the hydrogen desorption is size-dependent, as proven by different thermal analysis techniques.