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Effects of Thermal Fluctuations on the Hydroxylation and Reduction of Ceria Surfaces by Molecular H2
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2015-09-01 00:00:00 , DOI: 10.1021/acs.jpcc.5b07030 Fabio R. Negreiros 1 , Matteo Farnesi Camellone 1 , Stefano Fabris 1
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2015-09-01 00:00:00 , DOI: 10.1021/acs.jpcc.5b07030 Fabio R. Negreiros 1 , Matteo Farnesi Camellone 1 , Stefano Fabris 1
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The hydroxylation of oxide surfaces driven by molecular H2 dissociation plays a central role in a wide range of catalytic redox reactions. The high reducibility and oxygen storage capacity of ceria (CeO2) surfaces account for its extensive use as active catalyst support in these redox reactions. By means of ab initio molecular dynamics simulations, we investigate the hydroxylation and reduction of ceria surfaces and demonstrate the so-far unrecognized effects of atomic thermal fluctuations into the mechanism and kinetics of H2 dissociation. The reaction free-energy hypersurface is sampled and mapped at finite temperature by combining Hubbard-U density functional theory (DFT+U), ab initio molecular dynamics, metadynamics, and umbrella sampling methods. Our molecular dynamics simulations show that the explicit inclusion of thermal fluctuations into the reaction thermodynamics alters the mechanism of H2 dissociation, changes the nature of the rate-limiting transition state, and decreases the activation temperatures by more than 25%. The results are discussed in the context of kinetic measurements and provide novel insight into the hydroxylation and reduction steps that control the catalytic activity and selectivity of ceria surfaces.
中文翻译：
热涨落对分子H 2对羟基氧化铈表面羟化和还原的影响
由分子H 2解离驱动的氧化物表面的羟基化在广泛的催化氧化还原反应中起着核心作用。二氧化铈（CeO 2）表面的高还原性和储氧能力使其在这些氧化还原反应中广泛用作活性催化剂载体。通过从头算的分子动力学模拟，我们研究了二氧化铈表面的羟基化和还原，并证明了迄今为止尚未认识到的原子热涨落对H 2离解机理和动力学的影响。通过结合Hubbard- U密度泛函理论（DFT + U），从头算分子动力学，元动力学和伞式采样方法。我们的分子动力学模拟表明，将热波动明确包含在反应热力学中会改变H 2离解的机理，改变速率限制过渡态的性质，并使活化温度降低25％以上。在动力学测量的背景下讨论了结果，并提供了对控制氧化铈表面催化活性和选择性的羟基化和还原步骤的新颖见解。
更新日期：2015-09-01
中文翻译：
热涨落对分子H 2对羟基氧化铈表面羟化和还原的影响
由分子H 2解离驱动的氧化物表面的羟基化在广泛的催化氧化还原反应中起着核心作用。二氧化铈（CeO 2）表面的高还原性和储氧能力使其在这些氧化还原反应中广泛用作活性催化剂载体。通过从头算的分子动力学模拟，我们研究了二氧化铈表面的羟基化和还原，并证明了迄今为止尚未认识到的原子热涨落对H 2离解机理和动力学的影响。通过结合Hubbard- U密度泛函理论（DFT + U），从头算分子动力学，元动力学和伞式采样方法。我们的分子动力学模拟表明，将热波动明确包含在反应热力学中会改变H 2离解的机理，改变速率限制过渡态的性质，并使活化温度降低25％以上。在动力学测量的背景下讨论了结果，并提供了对控制氧化铈表面催化活性和选择性的羟基化和还原步骤的新颖见解。
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