Hydrogen Storage with Spectroscopic Identification of Chemisorption Sites in Cu-TDPAT via Spillover from a Pt/Activated Carbon Catalyst

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• 作者：Cheng-Yu Wang ; Jennifer L. Gray ; Qihan Gong ; Yonggang Zhao ; Jing Li ; Emmanuel Klontzas ; George Psofogiannakis ; George Froudakis ; Angela D. Lueking
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：November 20, 2014
• 年：2014
• 卷：118
• 期：46
• 页码：26750-26763
• 全文大小：746K
• ISSN：1932-7455

文摘

Hydrogen spillover to the Cu-TDPAT (TDPAT = 2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine) metal鈥搊rganic framework is probed with adsorption measurements, ex situ characterization techniques, and density functional theory (DFT) calculations. At 1 bar and 300 K, hydrogen chemisorption to Pt/AC/Cu-TDPAT exceeds that expected for physisorption by 8-fold, which is attributable to both catalyst insertion and the creation of structural defects. Hydrogenation of (a) the Cu鈥揙鈥揅 bond of the Cu paddlewheel, (b) the sp² N heterocycle, and (c) the secondary amine is demonstrated with ex situ spectroscopy. Exothermic (with respect to H₂) hydrogenation at the Cu鈥揙鈥揅 bond of the paddlewheel is substantiated by DFT. However, hydrogenated Cu鈥揙鈥揅 is metastable, as evidence for dissociation is found at higher temperature (i.e., 473 K H₂). DFT calculations demonstrate hydrogenation of the N groups may occur exothermically only for a charged ligand, suggestive that defects may contribute to hydrogen chemisorption. At high pressure, slow adsorption rates and material instability render the material unsuitable for practical hydrogen storage applications.