Facile construction of a hierarchical Bi@BiOBr–Bi2MoO6 ternary heterojunction with abundant oxygen vacancies for excellent photocatalytic nitrogen fixation

Abstract

Novel Bi@BiOBr–Bi₂MoO₆ ternary heterostructure photocatalysts were successfully prepared by a facile two-step solvothermal strategy, which presents a uniform spherical structure with around 200 nm. The composition, morphology and light-harvesting properties of Bi@BiOBr–Bi₂MoO₆ were characterized by XRD, XPS, SEM, TEM and DRS. As expected, the as-prepared heterojunction exhibits extraordinary photocatalytic activity for nitrogen fixation in water without any sacrificial agent. The results reveal that the optimized Bi@BOB–BMO-2 sample has an excellent NH₄⁺ yield rate of 167.2 μmol g⁻¹ h⁻¹, which is 2.5 and 2.1 times higher than that of pure Bi₂MoO₆ and Bi@BiOBr. The effect of an electron scavenger on the rate of NH₄⁺ production and the stability of Bi@BOB–BMO-2 was also investigated, and the results were desirable. This study provides a promising strategy to design superior simulated solar-light driven heterojunction photocatalysts with distinguished nitrogen fixation performance under mild conditions.