We demonstrate the direct observation of interatomic electron excitation and transfer on single-crystal TiO₂ (001) surface for water splitting by a synchronous illumination X-ray photoelectron spectroscopy (SI-XPS). The quantitative results clearly reveal that the initially absorbed water molecules on TiO₂ surface promote the electron transfer between Ti and O atoms. However, when water molecule was dissociated into OH and H groups on Ti and O sites, respectively, the electron excitation and transfer ability have been gradually decreased and finally terminated, probably due to the reverse electron-attraction of OH group on Ti atoms. Amazingly, when Pt co-catalyst was deposited on TiO₂, the electron excitation between Ti and O atoms have been significantly enhanced and no evident decrease has been observed during the entire water splitting process. In addition, the changes of Pt–O and Ti–O chemical bonds at the photocatalytic interfaces have been also detected. Furthermore, based on the above mechanism studies, the photocatalytic hydrogen production system for Pt/R-TiO₂ (001) in KOH solution containing CH₃OH was proposed, which exhibits a significant enhancement of hydrogen evolution rate (20.78 μmol h⁻¹), which is nearly 2.5 times higher than that of traditional Pt/R-TiO₂ (001) in CH₃OH system (8.35 μmol h⁻¹). The finding in this work may pave the way for developing other high-efficiency photocatalytic hydrogen production system over TiO₂-based photocatalysts.

我们展示了通过同步照明X射线光电子能谱（SI-XPS）对单晶TiO ₂（001）表面进行水分裂时原子间电子激发和转移的直接观察。定量结果清楚地表明，TiO ₂表面上最初吸收的水分子促进了Ti和O原子之间的电子转移。然而，当水分子分别在Ti和O位解离为OH和H基团时，电子的激发和转移能力逐渐降低并最终终止，这可能是由于OH基团在Ti原子上的反向电子吸引所致。令人惊讶的是，当Pt助催化剂沉积在TiO _2上时，Ti和O原子之间的电子激发得到了显着增强，并且在整个水分解过程中没有观察到明显的下降。此外，还检测到了光催化界面上Pt–O和Ti–O化学键的变化。此外，基于上述机理研究，提出了Pt / R-TiO ₂（001）在含CH ₃ OH的KOH溶液中的光催化制氢系统，该系统显着提高了析氢速率（20.78μmolh ^-1）。在CH ₃ OH体系中（8.35μmolh ^-1）是传统Pt / R-TiO ₂（001）的近2.5倍）。这项工作中的发现可能为在基于TiO ₂的光催化剂上开发其他高效的光催化制氢系统铺平道路。