In this article, we report a robust model for studying electrocatalytic reactions at metal nanoparticles (NPs) in contact with metal oxide surfaces. The metal oxide layer (TiO_x) is prepared by atomic layer deposition, and it is sufficiently thin that it does not hinder electron transfer from the underlying conductive electrode to the supported AuNP electrocatalysts. In advance of the experiments, density functional theory (DFT) predicted that direct contact between AuNPs and TiO_x would lead to enhanced activity for the oxygen reduction reaction (ORR). DFT attributes the observed ORR enhancement to partial charge transfer from oxygen vacancies within the TiO_x film to the supported AuNPs and hence formation of anionic Au species. The experimental findings are in near quantitative agreement with the DFT results. Specifically, compared to isolated AuNPs, decreases of ∼100 and ∼50 mV in the ORR onset potential are observed experimentally for AuNPs supported on TiO_1.9 and TiO_2.0 films, respectively.

中文翻译：

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TiO _x底物相互作用对金纳米粒子电催化氧还原反应的影响

在本文中，我们报告了一个健壮的模型，用于研究与金属氧化物表面接触的金属纳米颗粒（NPs）上的电催化反应。金属氧化物层（TiO _x）通过原子层沉积制备，并且足够薄以至于它不妨碍电子从下面的导电电极转移到负载的AuNP电催化剂。在实验之前，密度泛函理论（DFT）预测AuNP和TiO _x之间的直接接触将导致增强的氧还原反应（ORR）活性。DFT将观察到的ORR增强归因于TiO _x中氧空位引起的部分电荷转移膜到负载的AuNPs，从而形成阴离子Au物种。实验结果与DFT结果几乎定量吻合。具体而言，与分离的AuNPs相比，分别在TiO _1.9和TiO _2.0膜上负载的AuNPs的实验观察到ORR起始电位分别降低了约100和50 mV 。