One-pot synthesis of double vacancy tazetta Bi5O7I for photocatalytic removal of mercury from flue gas

Abstract

Regulation of carrier capture and transport is critical for the enhancement of photocatalytic activity. In this work, a Bi5O7I photocatalyst containing double vacant tazetta-like structure was synthesized by one-pot calcination. X-ray photoelectron spectroscopy (XPS) and electron spin resonance spectroscopy (ESR) analysis showed that the vacancy structure improved the activation performance of adsorbed oxygen, thereby promoting the participation of superoxide radicals in the photocatalytic reaction. The results of electron paramagnetic resonance (EPR), electrochemical impedance spectroscopy (EIS) and time-resolved photoluminescence spectroscopy (TRPL) revealed that the defect state induced by double vacancies could adjust the electron transport pathway, and the fluorescence lifetime could reach 3.043 ns, which greatly improved the photocatalytic reactivity. We further tested the photocatalytic activity of heavy metal mercury removal experiment, and the optimal photocatalytic mercury removal efficiency increased to 83%. Finally, combining the results of DFT calculation and photocatalytic mercury removal experiments, we proposed the photocatalytic reaction mechanism of Bi5O7I regulated by double vacancies. Our work provides a more convenient method for the design of defect engineering photocatalysts and provides effective theoretical support for photocatalytic removal of heavy metal mercury in flue gas.