Oxygen defects-induced charge transfer in Bi7O9I3 for enhancing oxygen activation and visible-light degradation of BPA

Two-dimensional (2D) bismuth-based semiconductors have aroused intensive concern owing to their prominent photocatalytic activity for organic pollutants removal. In this work, a facile strategy for introducing oxygen vacancy in Bi-based oxyiodides (BixOyIz) sheet-like architectures to activate molecular oxygen was proposed. 'rhe structure, photoelectric properties and visible light (lambda > 420 nm) induced photocatalytic activities of these samples for decomposition of bisphenol A (BPA) were systematically characterized and evaluated. The asprepared Bi7O9I3 with a feeding BO molar ratio of 1:1 exhibited the best photocatalytic activity comparable to those of similarly synthesized Bi7O9I3 with other molar ratios and BiOIO3 catalysts. The optimal Bi7O9I3 achieved excellent photocatalytic activity with 99.6 % degradation efficiency of BPA within 20 min and superior structural stability with 95.1 % degradation retention over 5 cycling tests. In addition, the resulting Bi7O9I3 sample displayed a high mineralization efficiency of BPA. Importantly, the plenty of oxygen vacancies (V-os) exsiting in Bi7O9I3 played the dominant role in both accelerating electron transfer and activating molecular oxygen to facilitate the generation of superoxide radical (O-2(center dot-)) and singlet oxygen (O-1(2)), thereby proceeding oxidative degradation of BPA molecules during photoreactions. The efforts and attempts are also extendable to synthesis other 2D photocatalysts, providing potential for effective charge-carrier separation and molecular oxygen activation.

Automated summary

This study proposed a facile strategy to introduce oxygen vacancies in Bi-based oxyiodides for activating molecular oxygen and achieving efficient photocatalytic degradation of BPA. The optimized Bi7O9I3 exhibited excellent photocatalytic activity and structural stability, with oxygen vacancies playing a crucial role in enhancing electron transfer and activating molecular oxygen for degradation of BPA molecules. Such efforts may potentially be extended to the synthesis of other 2D photocatalysts for effective charge-carrier separation and molecular oxygen activation.