Enhanced Electron Transfer Using NiZn₂O₄ Embedded in Carbon Nanocages for Singlet Oxygen-Dominated Mineralization of...

The remediation of endocrine-disrupting compounds, such as bisphenol A (BPA), demands advanced oxidation technologies capable of ultrafast and selective pollutant destruction. Herein, we report the rational design and synthesis of NiZn₂O₄ nanoparticles embedded in carbon nanocages (NiZn₂O₄@CNs) derived from bimetallic zeolitic imidazolate frameworks (ZIF), for efficient BPA degradation. The unique hollow nanocage architecture, featuring a well-defined mesoporous structure inherited from the MOF precursor, facilitates the mass transfer of the reactants and products. More importantly, the constructed spinel-type NiZn₂O₄ active sites, in conjunction with the conductive carbon matrix, endow the catalyst with an exceptional electron shuttle effect, which significantly accelerates the electron transfer from BPA to PMS. Consequently, the optimized NiZn₂O₄@CNs catalysts achieve an outstanding BPA degradation efficiency of 99% within only 5 min, reaching the high kinetic rate of 0.5382 min^-1. Quenching experiments and electron paramagnetic resonance tests reveal that singlet oxygen (¹O₂) is the dominant reactive oxygen species in the catalytic system. The catalyst further demonstrates exceptional stability, reusability, and broad applicability against diverse phenolic contaminants. This work provides a foundational blueprint for designing MOF-derived electron-shuttle catalysts, advancing the frontier of pollutant-specific advanced oxidation processes.