Nonadiabatic Dynamics of Photocatalytic Water Splitting on A Polymeric Semiconductor.

To elucidate the nature of light-driven photocatalytic water splitting, a polymeric semiconductor-graphitic carbon nitride (g-CN)-has been chosen as a prototype substrate for studying atomistic water spitting processes in realistic environments. Our nonadiabatic quantum dynamics simulations based on real-time time-dependent density functional theory reveal explicitly the transport channel of photogenerated charge carriers at the g-CN/water interface, which shows a strong correlation to bond re-forming. A three-step photoreaction mechanism is proposed, whereas the key roles of hole-driven hydrogen transfer and interfacial water configurations were identified. Immediately following photocatalytic water splitting, atomic pathways for the two dissociated hydrogen atoms approaching each other and forming the H gas molecule are demonstrated, while the remanent OH radicals may form intermediate products (e.g., HO). These results provide critical new insights for the characterization and further development of efficient water-splitting photocatalysts from a dynamic perspective.