Toward Practical Water Decontaminations via Peroxymonosulfate Nonradical Oxidation: The Role of Cocatalyst MoS<sub>2</sub> with Sulfur Vacancies
Zhongxu Li, Yang Huo, Tian‐Ren Li, Shuangshi Dong, Mingxin Huo, Gang Liu, Meng Sun
Abstract
Molybdenum disulfide (MoS 2 ) is a prevalent cocatalyst for peroxymonosulfate (PMS) activation with iron-based materials. The contribution of molybdenum atoms in cocatalyst MoS 2 to iron regeneration during PMS activation has been broadly known, though the role of sulfur atoms remains explored. Here, we applied a one-step, facile means to prepare particulate Fe 3 O 4 supported by wrinkled MoS 2 with discernible sulfur vacancies (S V ), forming a flower-like Fe 3 O 4 –MoS 2 composite catalyst. We demonstrated, for the first time, a strong affinity of S V to PMS, facilitating the formation of an intermediate Fe III –PMS* while modulating the generation of pivotal nonradical species. Using an extensive characterization, we confirmed the simultaneous generation of high-valent iron-oxo species (≡Fe IV ═O) and singlet oxygen ( 1 O 2 ) during PMS activation with the Fe 3 O 4 –MoS 2 catalysts. In addition, we proposed that the ≡Fe IV ═O stemmed from the Fe III –PMS* precursor, which underwent heterolytic cleavage of the O–O bonds and concomitant rearrangement of oxygen atoms. Meanwhile, 1 O 2 is excited by PMS and formed by active oxygen (O*) liberated from iron oxides. Consequently, the Fe 3 O 4 –MoS 2 catalysts showed impressive performance in removing typical micropollutants from real water sources, such as secondary effluent from wastewater treatment plants, tap water, and surface water stream. Our study provides new insights into a nonradical pathway for PMS activation with Sv-containing MoS 2, clearing the way for developing high-performance MoS 2 catalysts for water decontamination.