Nd3+ induces three-dimensional hierarchical rosette-shaped Bi3O4Br to generate abundant oxygen vacancies for enhanced photocatalytic activity

Three-dimensional hierarchical rosette-shaped Bi₃O₄Br has been successfully prepared by a one-step hydrothermal method for the first time, in which the doping of Nd³⁺ into the matrix of Bi₃O₄Br induces abundant oxygen vacancies and triggers energy-band hybridization to produce new dopant levels, which can efficiently receive photo-excited electrons and inhibit the complexation of photogenerated carriers. Impressively, the doped energy levels act as “springboards” for photogenerated electron jumps, exacerbating the inhomogeneity of charge distribution and accelerating charge separation. In addition, the fine-tuning of Nd³⁺ improves the band structure and photocatalytic performance of Nd/Bi₃O₄Br. Notably, the unique 3D rosette-like Bi₃O₄Br could enhance the adsorption capacity of the catalyst and provide more opportunities for the introduction of Nd³⁺ to induce the generation of abundant oxygen vacancies. Both experimental and density functional theory (DFT) results reveal the synergistic effect of energy band hybridization and oxygen vacancies. In addition, comparative experiments showed that Nd/Bi₃O₄Br enhanced the maximum removal efficiency of heavy metal mercury by 29.66 % relative to Bi₃O₄Br under visible light. The present work reveals the reaction mechanism of photocatalytic oxidation for mercury removal, which provides a new direction for realizing energy conversion and environmental purification in the future.