Rational fabrication of flower-like BiOI1-x photocatalyst by modulating efficient iodine vacancies for mercury removal and DFT study

Abstract In this work, a high performance photocatalyst by integrating iodine vacancy of bismuth oxyiodide (BiOI) was designed, having rich iodine vacancy and superior photocatalytic activity. Specifically, the mechanisms for the formation of iodine vacancy and reaction process were investigated. Further, a novel iodine vacancy flower-like BiOI1-x photocatalyst were successfully fabricated, in which the Bi5O7I nanoparticles were in-situ crystallized by using pristine BiOI and calcination method. The morphology and microstructure, physicochemical, and photoelectrochemical properties of photocatalyst were fully characterized. The photocatalytic performance of iodine vacancy flower-like BiOI1-x photocatalyst was evaluated with removal mercury, which the gaseous mercury is difficult to be removed. The iodine vacancy flower-like BiOI1-x photocatalyst possessed excellently enhanced photocatalytic efficiency for the removal of gaseous mercury under visible light irradiation. The results show that the defective flower-like Bi-410 °C photocatalyst exhibits excellent photocatalytic performance, which manifests a mercury removal efficiency of 68.89% under visible light. Further, the photocatalyst showed favourable stability. Combined with theoretical simulation, the density function theory calculations (DFT) demonstrate that the iodine vacancy BiOI photocatalyst possess a positive VBM position due to calcination process. This work promises good prospect for the design of defect engineering materials for use in energy and environmental restoration.