Elucidating the mechanism of photoinduced water splitting on TiO₂ is important for advancing the understanding of photocatalysis and the ability to control photocatalytic surface reactions. However, incomplete experimental information and complex coupled electron–nuclear motion make the microscopic understanding challenging. Here we analyse the atomic-scale pathways of photogenerated charge carrier transport and photoinduced water dissociation at the prototypical water–rutile TiO₂(110) interface using first-principles dynamics simulations. Two distinct mechanisms are observed. Field-initiated electron migration leads to adsorbed water dissociation via proton transfer to a surface bridging oxygen. In the other pathway, adsorbed water dissociation occurs via proton donation to a second-layer water molecule coupled to photoexcited-hole transfer promoted by in-plane surface lattice distortions. Two stages of non-adiabatic in-plane lattice motion—expansion and recovery—are observed, which are closely associated with population changes in Ti3d orbitals. Controlling such highly correlated electron–nuclear dynamics may provide opportunities for boosting the performance of photocatalytic materials.

阐明 TiO ₂ 上光诱导水分解的机制对于增进对光催化的理解和控制光催化表面反应的能力具有重要意义。然而，不完整的实验信息和复杂的耦合电子-核运动使微观理解变得具有挑战性。在这里，我们使用第一原理动力学模拟分析了原型水-金红石 TiO ₂ (110) 界面处光生载流子传输和光致水解离的原子尺度路径。观察到两种不同的机制。场引发的电子迁移通过质子转移到表面桥接氧导致吸附的水解离。在另一种途径中，吸附水解离是通过向第二层水分子提供质子而发生的，该第二层水分子与面内表面晶格畸变促进的光激发空穴转移耦合。观察到非绝热面内晶格运动的两个阶段——膨胀和恢复，这与Ti3d轨道的布居变化密切相关。控制这种高度相关的电子-核动力学可能为提高光催化材料的性能提供机会。