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Electrocatalytic Study of the Oxygen Reduction Reaction at Gold Nanoparticles in the Absence and Presence of Interactions with SnOx Supports
Journal of the American Chemical Society ( IF 15.0 ) Pub Date : 2018-10-12 , DOI: 10.1021/jacs.8b08036
Nevena Ostojic 1 , Zhiyao Duan 1 , Aigerim Galyamova 1 , Graeme Henkelman 1 , Richard M. Crooks 1
Affiliation  

Here we report that density functional theory (DFT) can be used to accurately predict how Au nanoparticle (NP) catalysts cooperate with SnO x ( x = 1.9 or 2.0) supports to carry out the oxygen reduction reaction (ORR). Specifically, dendrimers were used to encapsulate AuNPs and prevent their interactions with the underlying SnO x supports. After removal of the dendrimers, however, the AuNPs are brought into direct contact with the support and hence feel its effect. The results show that both SnO1.9 and SnO2.0 supports strongly enhance the electrocatalytic properties of AuNPs for the ORR. In the case of AuNP interaction with a SnO1.9 support, the number of electrons involved in the ORR ( neff) increases from 2.1 ± 0.2 to 2.9 ± 0.1 following removal of the dendrimers, indicating an increased preference for the desired four-electron product (water), while the overpotential decreases by 0.32 V. Similarly, direct interactions between AuNPs and a SnO2.0 support result in an increase in neff from 2.2 ± 0.1 to 3.1 ± 0.1 and a reduction of the overpotential by 0.28 V. These experimental results are in excellent agreement with the theoretically predicted onset potential shift of 0.30 V. According to the DFT calculations, the observed activity enhancements are attributed to the existence of anionic Au resulting from electron transfer from surface oxygen vacancies within the SnO x supports to the AuNPs. This theoretical finding was confirmed experimentally using X-ray photoelectron spectroscopy. Importantly, the calculations reported here were performed prior to the experiments. In other words, this study represents an unusual case of theory accurately predicting the electrocatalytic manifestation of strong metal support interactions.

中文翻译:

在不存在和存在与 SnOx 载体相互作用的情况下金纳米颗粒的氧还原反应的电催化研究

在这里,我们报告密度泛函理论 (DFT) 可用于准确预测 Au 纳米颗粒 (NP) 催化剂如何与 SnO x (x = 1.9 或 2.0) 载体配合以进行氧还原反应 (ORR)。具体而言,树枝状聚合物用于封装 AuNPs 并防止它们与底层 SnO x 载体相互作用。然而,去除树枝状聚合物后,AuNPs 与载体直接接触,从而感受到其影响。结果表明,SnO1.9 和 SnO2.0 的载体都极大地增强了 AuNPs 对 ORR 的电催化性能。在 AuNP 与 SnO1.9 载体相互作用的情况下,去除树枝状聚合物后,参与 ORR (neff) 的电子数从 2.1 ± 0.2 增加到 2.9 ± 0.1,表明对所需四电子产物的偏好增加(水),而过电位降低 0.32 V。同样,AuNPs 和 SnO2.0 载体之间的直接相互作用导致 neff 从 2.2 ± 0.1 增加到 3.1 ± 0.1,并且过电位降低 0.28 V。这些实验结果非常好与理论预测的起始电位偏移 0.30 V 一致。根据 DFT 计算,观察到的活性增强归因于阴离子 Au 的存在,这是由于电子从 SnO x 载体内的表面氧空位转移到 AuNPs。使用 X 射线光电子能谱实验证实了这一理论发现。重要的是,这里报告的计算是在实验之前进行的。换句话说,
更新日期:2018-10-12
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