Abstract:

This study described the formation of amorphous MoS _x with a three-dimensional layer-by-layer structure by Mo₃S₁₃ clusters connected by disulfide bonds, and anchor Co in to the lamellar structure and highly dispersed using deposition method. The results indicated that the highly disordered structure in amorphous Co-MoS _x facilitated the exposure of more unsaturated active sites. Under the conditions of 0.5mL Co (NO₃)₂·6H₂O doping, 2mmol/L PMS concentration and pH=5, the 0.5MoS _x /PMS system degrade 95.96% of norfloxacin (NOR) within 40min. DFT calculations revealed that compared to MoS _x (-0.74eV), Co-MoS _x (-2.96eV)and PMS exhibited lower adsorption energy barriers. Hirshfeld charges revealed that the electron transfer number of Co-MoS _x (0.65e^-) with PMS was much higher than that of MoS _x (0.41e^-), leading to more significant electron rearrangement between Co-MoS _x and PMS and more complete activation of PMS. The valence cycle between Co²⁺/Co³⁺ and Mo⁴⁺/Mo⁵⁺/Mo⁶⁺ was the key to PMS activation. The analysis of active species indicated that the main source of ¹O₂ was the recombination of ·OH and the conversion of ·O{}_{\mathrm{2}}^{-}, and a reasonable NOR degradation pathway and corresponding mechanism analysis were proposed. The experiments with inorganic anions, ion leaching and different contaminants demonstrated the reusability, stability and non-selectivity of the 0.5 Co-MoS _x /PMS system for environmental applications.

Key words: MoS _x, Co single-atom, peroxymonosulfate, doping, norfloxacin

摘要：

介绍了Mo₃S₁₃团簇通过二硫键连接形成了具有三维逐层结构的非晶态MoS _x，通过沉积法将Co原子锚定在片层结构中并实现了高分散。结果表明，非晶态Co-MoS _x 中高度无序的结构有助于暴露出更多的不饱和活性位点。在0.5mL Co(NO₃)₂·6H₂O掺杂量、2mmol/L过氧单硫酸盐（PMS）浓度和pH=5的条件下，0.5Co-MoS _x /PMS体系在40min内降解了95.96%的诺氟沙星（NOR）。密度泛函理论（DFT）计算发现相对于MoS _x （-0.74eV），Co-MoS _x 与PMS间表现出更低的吸附能垒（-2.96eV）。Hirshfeld分析电荷表明，Co-MoS _x 与PMS的电子转移数（0.65e^-）远高于MoS _x （0.41e^-），导致了Co-MoS _x 和PMS之间更显著的电子重排和PMS更充分的活化。Co²⁺/Co³⁺和Mo⁴⁺/Mo⁵⁺/Mo⁶⁺之间的价态循环是PMS活化的关键。活性物种分析表明，¹O₂的主要来源为·OH的重组和·O{}_{\mathrm{2}}^{-}的转化，并提出了合理的NOR降解路径和相应的机理分析。通过无机阴离子、Co离子浸出和不同污染物对NOR降解的影响等实验证明了0.5Co-MoS _x /PMS系统在环境应用中的可重用性、稳定性和非选择性。

关键词: MoS _x, Co单原子, 过氧单硫酸盐, 掺杂, 诺氟沙星