Cu Deposited on CeOx-Modified TiO2(110): Synergistic Effects at the Metal–Oxide Interface and the Mechanism of the WGS Reaction

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• 作者：Jose J. Plata ; Jesús Graciani ; Jaime Evans ; José A. Rodriguez ; Javier Fernández Sanz
• 刊名：ACS Catalysis
• 出版年：2016
• 出版时间：July 1, 2016
• 年：2016
• 卷：6
• 期：7
• 页码：4608-4615
• 全文大小：591K
• 年卷期：0
• ISSN：2155-5435

文摘

Experimental techniques and DFT calculations have been combined to study and compare the effect of the metal–substrate interaction in Cu/TiO₂(110) and Cu/CeO_x/TiO₂(110) catalysts for the water–gas shift (WGS) reaction. Experiments and theory show that CeO_x nanoparticles affect the dispersion of copper on titania, and on the formed copper–ceria interface, there are synergistic effects which favor water dissociation and the WGS reaction. The minimum energy path for the WGS reaction on the new highly active catalytic system Cu/CeO_x/TiO₂(110) has been predicted by theoretical calculations. Main steps such as adsorption–dissociation of water and *OCOH carboxyl intermediate formation–deprotonation have been characterized. In this very particular system, water splitting is no longer the rate-limiting step because it can dissociate overcoming an energy barrier of only 0.92 kcal/mol. One important insight of the present work is to show that easy full hydration of the ceria particles strongly lowers the reaction barrier for the deprotonation of the *OCOH intermediate and facilitates the evolution of the WGS reaction. For the first time, a system has been found on which the WGS reaction is able to work with all the involved energy barriers below 12 kcal/mol. This remarkable behavior makes the metal/CeO_x/TiO₂ family a potential candidate for industrial application as catalysts in the WGS reaction. The change in the metal–support interactions when going from Cu/TiO₂ to Cu/CeO_x/TiO₂ illustrates the importance of optimizing the oxide phase when improving the performance of metal/oxide catalysts for the WGS.