Developing iron-based catalysts with superior activity and stability is a longterm goal for peroxymonosulfate (PMS) activation in advanced oxidation processes. Combining the confined interlayer growth strategy with melt infiltration under dry-chemical conditions, we successfully synthesized ultrathin 2D Fe 3 O 4 nanosheets with a monolayer thickness of about 1 nm. Atomic force microscopy, CS-corrected high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray absorption fine structure, etc. jointly revealed that the 2D Fe 3 O 4 nanosheets possessed special graphene-like morphology and enriched oxygen vacancies. As highly efficient AOP catalysts, a series of refractory organic pollutants, including phenolic compounds, antibiotics, and pharmaceuticals, were degraded and mineralized effectively via the activation of PMS. On the basis of radical quenching experiments, electrochemical analysis, and theory calculations, the radical generation (•OH and SO 4•− ) and mediated electron transfer were verified to be key mechanisms in the reaction. The oxygen vacancy-rich ultrathin 2D Fe 3 O 4 mediated the electron transfer between pollutions and oxidants, prompted the redox cycle of Fe 3 O 4 , and remarkably lowered the energy barrier for interfacial charge transfer. This work could generate 2D metal oxides nanosheets with sufficient oxygen vacancies in a large scale, leading the insight for boosting the activity of iron-based catalysts.
Incoherent interfaces with large mismatches usually exhibit very weak interfacial interactions so that they rarely generate intriguing interfacial properties. Here we demonstrate unexpected strong interfacial interactions at the incoherent AlN/Al2O3 (0001) interface with a large mismatch by combining transmission electron microscopy, first-principles calculations, and cathodoluminescence spectroscopy. It is revealed that strong interfacial interactions have significantly tailored the interfacial atomic structure and electronic properties. Misfit dislocation networks and stacking faults are formed at this interface, which is rarely observed at other incoherent interfaces. The band gap of the interface reduces significantly to ~ 3.9 eV due to the competition between the elongated Al-N and Al-O bonds across the interface. Thus this incoherent interface can generate a very strong interfacial ultraviolet light emission. Our findings suggest that incoherent interfaces can exhibit strong interfacial interactions and unique interfacial properties, thereby opening an avenue for the development of related heterojunction materials and devices.
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