Customized Ultrathin Oxygen Vacancy‐Rich Bi ₂ W _0.2 Mo _0.8 O ₆ Nanosheets Enabling a Stepwise Charge Separation Relay and Exposure of Lewis Acid Sites toward Broad‐Spectrum Photothermal Catalysis

Abstract Designing robust photocatalysts with broad light absorption, effective charge separation, and sufficient reactive sites is critical for achieving efficient solar energy conversion. However, realizing these aims simultaneously through a single material modulation approach poses a challenge. Here, a 2D ultrathin oxygen vacancy (Ov)‐rich Bi ₂ W _0.2 Mo _0.8 O ₆ solid solution photocatalyst is designed and fabricated to tackle the dilemma through component and structure optimization. Specifically, the construction of a solid solution with ultrathin structure initially facilitates the separation of photoinduced electron–hole pairs, while the introduction of Ov strengthens such separation. In the meantime, the presence of Ov extends light absorption to the NIR region, triggering a photothermal effect that further enhances the charge separation and accelerates the redox reaction. As such, photoinduced charge carriers in the Ov‐Bi ₂ W _0.2 Mo _0.8 O ₆ are separated step by step via the synergistic action of 2D solid solution, O _V , and solar heating. Furthermore, the introduction of O _V exposes surface metal sites that serve as reactive Lewis acid sites, promoting the adsorption and activation of toluene. Consequently, the designed Ov‐Bi ₂ W _0.2 Mo _0.8 O ₆ reveals an enhanced photothermal catalytic toluene oxidation rate of 2445 µmol g ⁻¹ h ⁻¹ under a wide spectrum without extra heat input. The performance is 9.0 and 3.9 times that of Bi ₂ WO ₆ and Bi ₂ MoO ₆ nanosheets, respectively.