Preparation of phosphorus-modified BiOx as versatile catalyst for enhanced photo-reduction of Cr(VI) and oxidation of organic dyes

The high-performance photocatalysts have received considerable attention in the field of environmental remediation. Herein, the synthesis of multi-phase BiOx nanocrystals decorated by phosphorus dopant is reported through a facile one-pot solvothermal method. The resulting P0.15BiOx photocatalyst exhibited an optimal Cr (VI) reduction and RhB oxidation rates of 84% and 96% under visible light irradiation, being nearly 2 times higher than that of pristine BiOx sample. The improved photocatalytic performance could be ascribed to the synergetic effects of well-matched band positions via formation of new electron evolution pathway, efficient charge carrier mobility and introducing electronic defects by insertion of P5+ ions into the structure. Furthermore, DFT presented formation of mid-gap hybrid of p states, which enhanced the light absorption capacity. The photocatalytic mechanism revealed the photogenerated holes were dominant. Moreover, the P0.15BiOx had quite stable crystal structure and recycling ability. In this work, we obtained a single metal oxide with polycrystalline nature which obtains better charge separation compared to the pure phases, leading to capability of the photocatalyst for both photo-oxidation and photo-reduction processes. The present study provides new insights into the design of atomic-level structural defects in the photocatalysts by a facile method, for efficient removal of heavy metal ions and dyes from the wastewater.