Vibration-enhanced photocatalytic performance of magnetically recyclable CoFe2O4-anchored Ni-MOF heterojunction for polluted water remediation

Recent research has shown that vibration enhanced magnetic heterojunction-based catalysis is a viable and effective substitute for sunlight- driven photocatalysis, in which redox processes are prompted by mechanical vibrations. In this study, CoFe 2 O 4 /Ni-MOF (CFO x /Ni-MOF y ) composite vibration enhanced magnetically recoverable photocatalysts (where x = 70 wt% and 30 wt%, y = 30 wt% and 70 wt%) were fabricated by the simplistic hydrothermal and solvothermal processes for effective photocatalytic degradation of organic pollutant (Congo red (CR)). Analysis using X-ray diffraction (XRD) demonstrated the development of a crystalline inverse spinel CFO phase and a well-preserved Ni-MOF framework. Conversely, Williamson-Hall (W-H) analysis indicated nanoscale crystallite sizes ranging from 15 to 36 nm, with optimum strain in CFO 30% /Ni-MOF 70% . Strong interfacial electronic contacts, oxygen vacancies, and surface hydroxyl groups were observed by X-ray photoelectron spectroscopy (XPS), all of which are beneficial to charge separation and catalytic activity. Morphological tests using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that CFO nanoparticles (8–15 nm) were uniformly dispersed over flower-like Ni-MOF nanosheets. This enabled the formation of a well-defined heterointerface, which in turn enhanced charge transfer. With a tuned band gap of around 2.6 eV, UV-Vis diffuse reflectance spectroscopy (UV-DRS) demonstrated that CFO 30% /Ni-MOF 70% exhibited prolonged visible-light absorption, which enabled effective photocatalytic performance. Among the fabricated samples, CFO 30% /Ni-MOF 70% composite had outstanding vibration-assisted photocatalytic activity. It was able to achieve 99.4% degradation of CR in just 50 min, which was a substantial improvement over the performance of pristine CFO (42%) and Ni-MOF (68%). Through the use of trapping experiments, it was determined that the most reactive species are • O 2 ⁻ and OH. It is believed that synergistic factors, such as better mass transfer under vibration, magneto-mechanical strain of CFO, high surface area of Ni-MOF, and effective type-I heterojunction charge transfer, are responsible for the enhanced performance. Additional evidence that the catalyst can be reused was provided by the fact that it exhibited remarkable stability over the course of five cycles. The results suggest that CFO 30% /Ni-MOF 70% nanocomposites are highly promising for multifunctional catalytic applications, combining mechanical strain, photo-, magnetoelectric activation for efficient water purification and green oxidant production.