Electron dynamics of tip-tunable oxygen species on TiO2 surface
Electron dynamics of tip-tunable oxygen species on TiO2 surface
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DOI：
10.1038/s43246-021-00176-5
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发表时间：
2021-07-01
影响因子：
7.8
通讯作者：
Kantorovich, Lev
中科院分区：
文献类型：
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作者：
Adachi, Yuuki;Brndiar, Jan;Kantorovich, Lev
通过改变原子力显微镜针尖所施加的偏置电压，电子隧穿可改变二氧化钛表面氧物种的氧化还原态。然而，隧穿本质上是随机的，通常需要超低温度才能获得具有统计意义的数据。在此，我们使用一种高灵敏度的快速原子力显微镜装置，在78 K下研究二氧化钛表面氧原子以活性氧物种和单原子量子点形式存在的氧化还原转变。我们实验装置的快速和高灵敏度特性使得无需借助超低温度就能收集到具有统计必要性的数据量。这使我们能够研究多个量子点，并深入了解氧物种之间的电子结构和相关性，而这是标准原子力显微镜无法实现的。我们表明单原子量子点存在两种电荷态，其电导差异极大，一种是导电的，另一种是不导电的。二氧化钛表面的氧物种存在不同的氧化还原态，可通过原子力针尖的电子隧穿在这些态之间切换。在此，一种快速的实验装置能够确定具有统计意义的隧穿速率，揭示电子结构的变化。
The redox states of oxygen species on the surface of TiO2 can be altered by electron tunneling by varying the applied bias voltage of an atomic force microscope tip. However, tunneling is stochastic in nature and typically requires ultra-low temperatures to obtain statistically significant data. Here, we use a highly sensitive fast atomic force microscopy setup to study redox transitions of oxygen atoms on a TiO2 surface, in the form of reactive oxygen species and single-atom quantum dots, at 78 K. The fast and highly sensitive nature of our experimental setup enables a statistically necessary amount of data to be collected without having to resort to ultra-low temperatures. This enabled us to study multiple dots and provide insight into the electronic structure and correlation between the oxygen species, which are inaccessible by standard atomic force microscopy. We show that single-atom quantum dots exist in two charge states with drastically different conductance, with one being conducting and the other non-conducting. Oxygen species on a TiO2 surface exist in different redox states, which can be switched between by electron tunneling with an atomic force tip. Here, a fast experimental setup enables statistically significant tunneling rates to be determined, revealing changes in electronic structure.