介孔碳模板中嵌入的超小 Pd 团簇的尺寸依赖性氢吸附。

Size-dependent hydrogen sorption in ultrasmall Pd clusters embedded in a mesoporous carbon template.

机构信息

Institut de Chimie et des Matériaux Paris Est, UMR 7182, CNRS, Thiais, France.

出版信息

J Am Chem Soc. 2010 Jun 9;132(22):7720-9. doi: 10.1021/ja101795g.

PMID:20465254

Abstract

Hydrogen sorption properties of ultrasmall Pd nanoparticles (2.5 nm) embedded in a mesoporous carbon template have been determined and compared to those of the bulk system. Downsizing the Pd particle size introduces significant modifications of the hydrogen sorption properties. The total amount of stored hydrogen is decreased compared to bulk Pd. The hydrogenation of Pd nanoparticles induces a phase transformation from fcc to icosahedral structure, as proven by in situ XRD and EXAFS measurements. This phase transition is not encountered in bulk because the 5-fold symmetry is nontranslational. The kinetics of desorption from hydrogenated Pd nanoparticles is faster than that of bulk, as demonstrated by TDS investigations. Moreover, the presence of Pd nanoparticles embedded in CT strongly affects the desorption from physisorbed hydrogen, which occurs at higher temperature in the hybrid material compared to the pristine carbon template.

摘要

已确定并比较了嵌入在介孔碳模板中的超小 Pd 纳米粒子（2.5nm）的氢气吸附性能与体相系统的性能。将 Pd 颗粒尺寸减小会显著改变氢气吸附性能。与体相 Pd 相比，存储的氢气总量减少。Pd 纳米粒子的加氢会诱导从 fcc 到二十面体结构的相转变，这一点通过原位 XRD 和 EXAFS 测量得到了证明。由于 5 重对称性是非平移的，因此在体相中不会遇到这种相变。通过 TDS 研究证明，从加氢 Pd 纳米粒子中脱附的动力学比体相快。此外，嵌入在 CT 中的 Pd 纳米粒子的存在强烈影响物理吸附氢的脱附，与原始碳模板相比，在混合材料中，物理吸附氢在更高的温度下发生脱附。