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.