Theory-guided unraveling of the mechanism underlying Cu1.0/Mn1.0-ZnO with dual reaction centers for enhanced peroxymonosulfate activation

Developing efficient catalytic systems for water contamination removal is a topic of great interest. However, the use of heterogeneous catalysts faces challenges due to insufficient active sites and electron cycling. In this study, results from first-principles calculations demonstrate that dual reaction centers (DRCs) are produced around the Cu and Mn sites in Cu1.0/Mn1.0-ZnO due to the electronegativity difference. Experimental results reveal the material with DRCs greatly enhances electron transfer efficiency and significantly impacts the oxidation and reduction of peroxymonosulfate (PMS). In addition, the self-consistent potential correction (SCPC) method was introduced to correct the energy and charge of charged periodic systems simulating a catalytic process, resulting in more precise catalytic results. Specifically, the material exhibits a preference for adsorbing negatively charged PMS anions at electron-deficient Mn sites, facilitating PMS oxidation for the generation of 1O2, and PMS reduction around the electron-rich Cu for the formation of •OH and SO4•-. The major reactive oxygen species is 1O2, showcasing effective performance in various degradation systems. Overall, our work provides novel insights into the persulfate-based heterogeneous catalytic oxidation process, paving the way for the development of high-performance catalytic systems for water purification.

Degradation of orange II by Fe@Fe2O3 core shell nanomaterials assisted by NaHSO3

Fe@Fe₂O₃ core shell nanomaterials with different Fe₂O₃ shell thickness were synthesized and the Fe@Fe₂O₃/NaHSO₃ Fenton-like system was used for the decomposition of Orange II. The consequences are compared with traditional Fenton Fe@Fe₂O₃/H₂O₂ system. The Fe@Fe₂O₃/NaHSO₃ system showed extremely good applicability under both strongly acidic and alkaline conditions. The new Fe@Fe₂O₃-(2)/NaHSO₃ system led to more than 99% degradation in 30 s when the pH was 3, which indicated that the Fe@Fe₂O₃ material was not corroded during the process even under strongly acidic condition. The above Fe@Fe₂O₃-(2) material was prepared from nano-zero-valent iron aged in solution for 2 h to synthesize the Fe₂O₃ shell. The reaction mechanism of Fe@Fe₂O₃/NaHSO₃ Fenton-like system was also concluded. The oxidation efficiency was highly improved due to rapid electron transfer between Fe core and Fe₂O₃ shell, which promoted the direct recycling of ≡Fe³⁺ and ≡Fe²⁺ and thus accelerated the generation of SO₄^- and OH radicals.