Sonochemical Engineering of Atomic Pb─O─Zn Bridges for Robust Z-Scheme Overall Pure Water Splitting

Efficient photocatalytic overall water splitting is often constrained by the fundamental trade-off between charge separation efficiency and redox driving force in conventional heterojunctions. Direct Z-scheme architectures theoretically resolve this dilemma, yet constructing robust, defect-free interfaces remains a formidable synthetic challenge. Here, we introduce a sonochemical strategy in which transient cavitation drives the in situ insertion of Zn during the growth of In₂S₃ on PbTiO₃, giving rise to interfacial Pb─O─Zn bridges. These Zn bridges convert the junction from type-II to a direct Z-scheme, enabling selective interfacial recombination while preserving high oxidation and reduction potentials. Multimodal spectroscopic and density functional theory confirmed the Z-scheme pathway and prolonged carrier lifetimes. The resulting photocatalyst delivers stoichiometric H₂ and O₂ evolution rates of 166.6 and 81.7 µmol h⁻¹, demonstrating a competitive performance within reported Z-scheme heterostructure-based photocatalysts. This transient cavitation-driven heteroatom insertion strategy provides a potentially general and programmable protocol for engineering precise semiconductor interfaces and constructing direct Z-scheme junctions for solar fuel production.