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arXiv 2104.10992cond-mat.mtrl-sci
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CeO2中pH-Driven氧空位形成-消除的DFT研究

DFT Investigation of pH-Driven Oxygen Vacancy Formation-Annihilation in CeO2

Hongyang Ma, Hangjuan Ren, Zhao Liu, Pramod Koshy, Charles C. Sorrell, Judy N. Hart

摘要:

在生物医学中,氧化铈纳米颗粒(CeNPs)的pH依赖性可切换的生物催化性质中有相当大的兴趣,其中这些材料在中性和碱性生理pH下对活性氧物种表现出有益的抗氧化活性,但在酸性病理pH下具有细胞毒性促氧化活性。氧空位在这种生物催化活性中起着关键作用。虽然氧空位的作用的一般特征是已知的,但它们在不同pH条件下在原子尺度上的作用机制还有待阐明。本文采用密度泛函理论(DFT)在原子尺度上对CeO 2稳定的{111}表面的pH诱导行为进行了研究。表面吸附介质物种的分析揭示了pH值的Ce 3+和Ce 4+氧化还原平衡的可逆性和氧空位的形成和湮灭的关键作用。在酸性条件下,由于水分子中的氧对氧空位的不完全体积填充,这种可逆转换受到阻碍,因此有效地保留了氧空位,并因此抑制了氧化还原仿生反应。在中性和碱性条件下,由于OH离子由于其现成的尺寸容纳而完全填充氧空位,因此保留了这种可逆切换的能力,从而保留了循环进行氧化还原仿生反应的能力。

英文摘要:

There is considerable interest in the pH-dependent switchable biocatalytic properties of cerium oxide nanoparticles (CeNPs) in biomedicine, where these materials exhibit beneficial antioxidant activity against reactive oxygen species at neutral and basic physiological pH but cytotoxic prooxidant activity at acidic pathological pH. Oxygen vacancies play a key role in such biocatalytic activities. While the general characteristics of the role of oxygen vacancies are known, the mechanism of their action at the atomic scale under different pH conditions has yet to be elucidated. The present work applies density functional theory (DFT) calculations to interpret the pH-induced behavior of the stable {111} surface of CeO2 at the atomic scale. Analysis of the surface-adsorbed media species reveals the critical role of pH on the reversibility of the Ce3+ and Ce4+ redox equilibria and the formation and annihilation of the oxygen vacancies. Under acidic conditions, this reversible switching is hindered owing to incomplete volumetric filling of the oxygen vacancies by the oxygen in the water molecules, hence effective retention of the oxygen vacancies, and consequent inhibition of redox biomimetic reactions. Under neutral and basic conditions, the capacity for this reversible switching is preserved due to complete filling of the oxygen vacancies by the OH ions owing to their ready size accommodation, thereby retaining the capacity for performing redox biomimetic reactions cyclically.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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