A study explores the photocatalytic oxidation of toluene using Ni-doped monolayer Bi₂WO₆ nanosheets (Ni/BWO) to create cascaded active units (CAUs) for efficient C–H bond oxidation. The Ni dopants introduce unsaturated W atoms and Bi/O frustrated Lewis pairs (FLPs), enabling efficient oxygen transfer and C–H bond activation. Experimental and theoretical analyses show that the Ni/BWO catalyst with 1.8% Ni mass fraction achieves high toluene conversion (4560 μmol g⁻¹ h⁻¹) and high selectivity towards benzaldehyde. The CAUs, formed through Ni-mediated surface defects and spatially separated Bi/O atoms, facilitate the activation of O₂ and C–H bonds, enhancing photocatalytic performance. The study highlights the importance of designing CAUs for efficient C–H bond oxidation, demonstrating the potential of Ni-doped Bi₂WO₆ as a promising photocatalyst for toluene oxidation. The results provide insights into the role of surface defects, FLPs, and active oxygen species in photocatalytic reactions, offering a new strategy for improving catalytic efficiency in C–H bond oxidation.A study explores the photocatalytic oxidation of toluene using Ni-doped monolayer Bi₂WO₆ nanosheets (Ni/BWO) to create cascaded active units (CAUs) for efficient C–H bond oxidation. The Ni dopants introduce unsaturated W atoms and Bi/O frustrated Lewis pairs (FLPs), enabling efficient oxygen transfer and C–H bond activation. Experimental and theoretical analyses show that the Ni/BWO catalyst with 1.8% Ni mass fraction achieves high toluene conversion (4560 μmol g⁻¹ h⁻¹) and high selectivity towards benzaldehyde. The CAUs, formed through Ni-mediated surface defects and spatially separated Bi/O atoms, facilitate the activation of O₂ and C–H bonds, enhancing photocatalytic performance. The study highlights the importance of designing CAUs for efficient C–H bond oxidation, demonstrating the potential of Ni-doped Bi₂WO₆ as a promising photocatalyst for toluene oxidation. The results provide insights into the role of surface defects, FLPs, and active oxygen species in photocatalytic reactions, offering a new strategy for improving catalytic efficiency in C–H bond oxidation.