Site-Dependent Activity of Atomic Ti Catalysts in Al-Based Hydrogen Storage Materials

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• 作者：Abdullah Al-Mahboob ; Erik Muller ; Altaf Karim ; James T. Muckerman ; Cristian V. Ciobanu ; Peter Sutter
• 刊名：The Journal of the American Chemical Society
• 出版年：2012
• 出版时间：June 27, 2012
• 年：2012
• 卷：134
• 期：25
• 页码：10381-10384
• 全文大小：303K
• 年卷期：v.134,no.25(June 27, 2012)
• ISSN：1520-5126

文摘

Doping catalytically inactive materials with dispersed atoms of an active species is a promising route toward realizing ultradilute binary catalyst systems. Beyond catalysis, strategically placed metal atoms can accelerate a wide range of solid-state reactions, particularly in hydrogen storage processes. Here we analyze the role of atomic Ti catalysts in the hydrogenation of Al-based hydrogen storage materials. We show that Ti atoms near the Al surface activate gas-phase H₂, a key step toward hydrogenation. By controlling the placement of Ti, we have found that the overall reaction, comprising H₂ dissociation and H spillover onto the Al surface, is governed by a pronounced trade-off between lowering of the H₂ dissociation barrier and trapping of the products near the active site, with a sharp maximum in the overall activity for Ti in the subsurface layer. Our findings demonstrate the importance of controlling the placement of the active species in optimizing the activity of dilute binary systems.