The ability of titanium dioixide to split water into OH⁻ and H⁺ species is heavily dependent on the behaviour of defects in the crystal structure at or near the surface. We present an in situ study of defect migration in rutile TiO₂(110) conducted using X-ray photoelectron spectroscopy (XPS). First, surface and subsurface defects were created in the crystal by argon ion sputtering. Subsequent in situ exposure of the defective crystal to liquid water healed the surface defects, whereas the subsurface remained defective. The sample was then annealed while XPS was used to monitor the concentration of titanium defects. At low annealing temperatures, Ti³⁺ was observed to migrate from the subsurface to the surface. Further annealing gradually restored the surface and subsurface to the defect-free Ti⁴⁺ form, during which the changes in abundance of Ti¹⁺, Ti²⁺ and Ti³⁺ defects are discussed.

中文翻译：

---

通过 XPS 原位探索亚表面缺陷迁移到液态水暴露的金红石 TiO2(110) 表面

二氧化钛将水分解为 OH ^-和 H ⁺物种的能力在很大程度上取决于表面处或表面附近的晶体结构中的缺陷行为。我们提出了使用 X 射线光电子能谱 (XPS) 进行的金红石 TiO ₂ (110)中缺陷迁移的原位研究。首先，通过氩离子溅射在晶体中产生表面和亚表面缺陷。随后将有缺陷的晶体原位暴露于液态水修复了表面缺陷，而次表面仍然有缺陷。然后对样品进行退火，同时使用 XPS 监测钛缺陷的浓度。在低退火温度下，Ti ³⁺观察到从地下迁移到地表。进一步退火逐渐将表面和亚表面恢复到无缺陷的 Ti ⁴⁺形式，在此期间讨论了Ti ¹⁺、Ti ²⁺和 Ti ³⁺缺陷丰度的变化。