Radiation-Induced Interfacial Hydroxyl Transformation on Boehmite and Gibbsite Basal Surfaces,The Journal of Physical Chemistry C

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Radiation-Induced Interfacial Hydroxyl Transformation on Boehmite and Gibbsite Basal Surfaces
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2020-09-11 , DOI: 10.1021/acs.jpcc.0c06844
Michel Sassi ₁ , Eric D. Walter ₂ , Odeta Qafoku ₁ , Kevin M. Rosso ₁ , Zheming Wang ₁

Affiliation

Understanding the radiolytic reactivity of aluminum oxyhydroxide phases widely present in stored nuclear wastes is essential to develop reliable processing approaches. Recent experiments using vibrational sum frequency generation (VSFG), a surface sensitive technique, have shown that rehydration of γ-irradiated boehmite (010) and gibbsite (001) surfaces does not recover the initial hydroxyl density prior to irradiation. Here, using density functional theory and nudged elastic band calculations, we examine dehydration and rehydration of these surfaces and attendant proton transfer mechanisms. While dehydration of both surfaces is predicted to be energetically unfavorable, rehydration of boehmite (010) is favorable after overcoming an energy barrier of 0.52 eV that relates to the orientation of surface hydroxyls controlling the hydrogen bonding network of adsorbed water. In the case of gibbsite (001), for which the experimental results suggest that rehydration mainly involves the reformation of interlayer hydroxyls, we found that a two-proton transfer mechanism is more likely than a one-proton transfer mechanism, and that it prevents the reorientation of interlayer hydroxyls into intralayer hydroxyls consistent with experimental VSFG findings. A detailed analysis of the effect of surface hydrogen vacancy on the strength of hydrogen bond interactions was performed, which indicates that H₂ and H₂O are the energetically most favorable product species to form from radiation-induced surface H and/or OH defects.

中文翻译：

勃姆石和菱镁矿基面辐射诱导的界面羟基转化

了解储存的核废料中广泛存在的氢氧化铝氢相的放射反应性对于开发可靠的处理方法至关重要。最近使用振动总频率生成（VSFG）（一种表面敏感技术）进行的实验表明，经γ辐射的勃姆石（010）和菱铁矿（001）表面的再水化不能恢复辐射前的初始羟基密度。在这里，我们使用密度泛函理论和微动的弹性带计算，研究了这些表面的脱水和再水化以及随之而来的质子转移机制。虽然预计两个表面的脱水在能量上都是不利的，但勃姆石（010）的水化克服了0的能垒之后是有利的。52 eV与控制吸附水的氢键网络的表面羟基的取向有关。在三水铝石（001）的情况下，实验结果表明水合主要涉及层间羟基的重整，我们发现两质子转移机制比单质子转移机制更有可能，并且防止了将层间羟基重新定向为层内羟基与实验VSFG结果一致。详细分析了表面氢空位对氢键相互作用强度的影响，表明H 我们发现，两质子转移机制比单质子转移机制更有可能，并且它可以防止层间羟基重新定向为层内羟基，这与实验VSFG的发现一致。详细分析了表面氢空位对氢键相互作用强度的影响，表明H 我们发现，两质子转移机制比单质子转移机制更有可能，并且它可以防止层间羟基重新定向为层内羟基，这与实验VSFG的发现一致。详细分析了表面氢空位对氢键相互作用强度的影响，表明H₂和H ₂ O是从辐射诱导的表面H和/或OH缺陷形成的能量上最有利的产品种类。

更新日期：2020-10-08

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