CdTe Quantum Dot/Bi₂WO₆ Nanosheet Photocatalysts with a Giant Built-In Electric Field for Enhanced Removal of Persistent Organic Pollutants

Constrained by the strong Coulombic interaction of electron–hole pairs in semiconductor photocatalysts, the charge carrier separation and the resultant photocatalytic capability are greatly compromised. In this work, we rationally construct a built-in electric field (BEF) from the (111) facet of CdTe quantum dots (CdTeQDs) to the (200) facet of two-dimensional Bi2WO6 (2DBWO) nanosheets by the formation of a Te–Ox bond. We validate experimentally and theoretically that the BEF can profoundly promote the dissociation of a photoexcited exciton and separation of a charge carrier, resulting in the formation of a Z-scheme electronic structure of the CdTeQDs/2DBWO photocatalyst. Benefiting from the role of the BEF, the photoinduced generation of the superoxide anion radical and hydroxyl radical is significantly promoted, based on which photodegradation performances of the CdTeQDs/2DBWO photocatalyst are 6.64, 1.95, and 5.4 times those of pure 2DBWO for tetracycline, phenol, and rhodamine B, respectively. This work provides a mechanistic insight into the design and optimization of semiconductor heterojunction photocatalysts for efficient charge carrier separation and environmental remediation.