This work, which overviews defect chemistry of TiO₂ (rutile), is focused on atomic-size structural defects that are thermodynamically reversible. Here it is shown that thermodynamics can be used in defect engineering of TiO₂-based energy materials, such as photoelectrodes and photocatalysts. We show that surface segregation of defects leads to the building-up of new surface structures that are responsible for reactivity. Since rational design of surface properties requires in situ surface characterization in operational conditions, expansion of bulk defect chemistry to surface defect chemistry requires a defect-related surface-sensitive tool for in situ monitoring of defect-related properties at elevated temperatures corresponding to defect equilibria and in a controlled gas-phase environment. Here we show that the high-temperature electron probe is a defect-related surface-sensitive tool that is uniquely positioned to aid surface defect engineering and determine unequivocal surface properties. The related applied aspects are considered for photoelectrochemical water splitting and the performance of solid oxide fuel cells. Here we report that trail-blazing studies on in situ surface monitoring of TiO₂ during gas/solid equilibration, along with in situ characterization of surface semiconducting properties, leads to the discovery of a segregation-induced low-dimensional surface structure that is responsible for stable performance of oxide semiconductors, such as TiO₂, in operational conditions.

中文翻译：

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二氧化钛（金红石）的缺陷化学。可持续能源的进展


这项工作概述了 TiO₂（金红石）的缺陷化学，重点是热力学上可逆的原子大小的结构缺陷。本文表明，热力学可用于基于 TiO₂ 的能源材料（如光电极和光催化剂）的缺陷工程。我们表明，缺陷的表面分离导致导致反应性的新表面结构的建立。由于表面特性的合理设计需要在操作条件下进行原位表面表征，因此将本体缺陷化学扩展到表面缺陷化学需要一种与缺陷相关的表面敏感工具，用于在对应于缺陷平衡的高温和受控气相环境中对缺陷相关特性进行原位监测。在这里，我们展示了高温电子探针是一种与缺陷相关的表面敏感工具，其独特位置有助于表面缺陷工程并确定明确的表面特性。考虑了光电化学分解水和固体氧化物燃料电池的性能。在这里，我们报告了在气/固平衡过程中对 TiO₂ 的原位表面监测的开创性研究，以及表面半导体特性的原位表征，导致了一种偏析诱导的低维表面结构的发现，该结构负责氧化物半导体（如 TiO₂）在操作条件下的稳定性能。