Synergistic effect of ultrathin thickness and surface oxygen vacancies in high-efficiency Ti-mediated Bi2MoO6 for immense photocatalytic nitrofurantoin degradation and Cr(VI) reduction

Highlights: • The Ti-doping can reduce the thickness, highly enhances the BET surface area and porosity, and mediates oxygen vacancies in Bi₂MoO₆. • The synergistic effect of ultrathin thickness and oxygen vacancies will promote the charge transport from bulk to surface. • Ti-doping can act as surface electron scavenger, which endows as-fabricated catalyst with charge collection ability to facilitate photogenerated e⁻/h⁺ separation. • In contrast with pristine Bi₂MoO₆, the Ti-mediated Bi₂MoO₆ ultrathin nanosheet exhibits higher photocatalytic activity. • The photoelectrochemical experiments confirm the promoted charge separation efficiency. Crystal defects have been broadly regarded to modulate the photoreactivity of semiconductors, mostly concerning the crystal and electronic structure of materials. On the other hand, oxygen defect-engineering is a fundamental approach to improve the photolysis activity of materials. Herein, an interactive hybrid intermediate strategy with oxygen defect-engineering was utilized to fabricate atomically-thin Ti-doped Bi₂MoO₆ nanosheets. Experimental results unveil that the well-engineered ultrathin Ti-doped Bi₂MoO₆ nanosheets tune the morphology, visible light absorption, local atomic and electronic band structure of Bi₂MoO₆. Importantly, the Ti-doping hugely affects the BET specific surface area and porosity of Ti-Bi₂MoO₆ (72 m² g⁻¹) in contrast to bulk Bi₂MoO₆, which is 19 m² g⁻¹. Furthermore, the density functional theory calculations were carried out to explore the effect of Ti-doping on electronic band structure and the surface charge distribution in Ti-Bi₂MoO₆. It was found, rather than acting as a recombination center for photogenerated charge carriers, the defect caused by Ti doping mediated O vacancies in the crystal structure of Bi₂MoO₆, which favors the photogenerated charge carriers transfer and enhances the photocatalytic reactivity due to delocalized nature. With the advantages of atomically-thin structure Ti-Bi₂MoO₆ nanosheets, the synergistic effect of ultrathin thickness of Ti-Bi₂MoO₆ and oxygen vacancies has remarkably improved the photocatalytic activity towards the degradation of nitrofurantoin, and photoreduction of Cr(VI) in a highly acidic and alkaline medium. The present work opens a door for enhancing the photolysis performance of Bi₂MoO₆-based photocatalysts with excellent photolysis activity in the various environmental remediation processes.