Oxygen vacancy mediated single unit cell Bi₂WO₆ by Ti doping for ameliorated photocatalytic performance

Crystal defects are crucially important in semiconductor photocatalysis. To improve the reactivity of photocatalysts and attain desirable solar energy conversion, crystal defect engineering has gained considerable attention in real catalysts. Herein, we engineered crystal defects and mediate oxygen vacancies in host Bi₂WO₆ crystal lattice via varying content of Ti dopant to fabricate single-unit-cell layered structure, resulting in enhanced visible-light-driven photocatalytic efficiency. Density functional theory (DFT) calculations verified that the substitution of Bi cation in the crystal structure of Bi₂WO₆ can induce a new defect level, and increase the density of states (DOS) at the valence band maximum, which not only improve the charge dynamic but also the electronic conductivity. Remarkably, the single-unit-cell layers Ti-doped Bi₂WO₆ structure casts profoundly improved photocatalytic performance towards ceftriaxone sodium degradation, Cr(VI) reduction, and particularly higher photocatalytic H₂ production rate, with a 5.8-fold increase compared to bulk Bi₂WO₆. Furthermore, the photoelectrochemical measurements unveil that the significantly higher charge migration and charge carrier dynamic counts for the elevated photocatalytic performance. After careful examination of experimental results, it was proved that the Ti doping mediated crystal defects, and engendered oxygen vacancies are critically important for controlling the photocatalytic performance of Bi₂WO₆.