A Z-scheme BiOCl/UiO-66(Zr/Ti) heterojunction with engineered interfacial contacts for synergistic pollutant mineralization and selective sulfoxidation

Abstract

Simultaneous deep mineralization of pollutants and selective oxidation of value-added substrates remains challenging due to the conflicting reactivity requirements of ·OH and ¹O₂. Here we construct a Z-scheme BiOCl/UiO-66(Zr/Ti) heterojunction in which work-function mismatch generates a built-in electric field that directs electrons to the MOF and holes to BiOCl. Ti is atomically dispersed within the UiO-66 framework, as confirmed by XAS and DFT, forming Zr–O–Ti bridges and oxygen vacancies that enhance charge separation. This spatial charge compartmentalization enables dual-ROS pathways: electrons accumulated on UiO-66 reduce O₂ to ·OH for deep mineralization (98% dye decolorization, 88% TOC removal), while holes retained on BiOCl generate ¹O₂ for selective sulfoxidation (70% conversion, 99% selectivity). Trace rhodamine B acts as an in situ photosensitizer, amplifying both pathways via electron injection and triplet energy transfer. The colloidal architecture maintains >90% activity in real water matrices and over eight cycles with low energy consumption. This work establishes interfacial electric field engineering as a generalizable strategy to integrate environmental remediation and selective synthesis in a single photocatalytic platform.