Gefitinib, a persistent anticancer contaminant with well-defined photochemical behavior, was used to test whether visible-light harvesting and oxygen activation can be separated within a single Bi2MoO6-based photocatalyst. A Sr/W-co-doped Bi2MoO6 core decorated with an ultrathin SrWO4 shell (3 wt%), denoted Sr/W-codoped BMO@SrW-3, was synthesized and compared with pristine Bi2MoO6 and Sr/W-co-doped Bi2MoO6. Integrated characterization across structure, surface chemistry, charge dynamics, degradation products, mineralization, and DFT modeling established a phase-preserved Aurivillius Bi2MoO6 core with hierarchical nanosheetflower architecture, uniform Sr/W incorporation, and a continuous 2-3 nm SrWO4 interfacial shell. The optimized composite increased surface accessibility, raised the work function to 5.18 eV, enriched oxygen-vacancy/ interfacial defect centers, decreased charge-transfer resistance to 212 Ω, and produced the strongest photocurrent response of 1.38 μA cm− 2 . In the three-material comparative experiment, Sr/W-co-doped BMO@SrW-3 degraded ~96% of GEF within 60 min with kapp = 0.0498 min− 1 , 2.62 times faster than pristine BMO, and exhibited the highest AQY of 5.8% at 420 nm. A separate operating-parameter optimization subsequently identified pH 7, 75 mg L− 1 catalyst dosage, and 2.5 mg L− 1 GEF as the optimum conditions, under which GEF degradation increased to ~99% with kapp = 0.054 min− 1 . Scavenger tests, molecular probes, and spin-trapping EPR established a hole/ ⋅OH-dominated pathway assisted by ⋅O22 − , with 1O2 as a secondary contributor. LC-MS revealed hydroxylation, dealkylation, dehalogenation, side-chain oxidation, ring opening, and fragmentation, while TOC removal reached 74 ± 2% after 180 min. DFT showed favorable interfacial binding, stronger GEF/ O2 adsorption, and enhanced electron transfer to O2. After 25 cycles, the catalyst retained ~92% activity, demonstrating durable bulk-surface photocatalysis governed by coupled light absorption, charge management, and oxygen activation under visible light.
