Metal ion-modulated synthesis of γ-MnO2 nanosheet for catalytic oxidative degradation of clomiprazole†

Two-dimensional non-layered oxide nanosheets exhibit exceptional catalytic properties, offering significant potential for environmental applications. In this study, we report the development of a novel Fe-doped γ-MnO₂ material with a hierarchical microsphere morphology, achieved through a metal ion regulation strategy. Unlike conventional sea urchin-like γ-MnO₂, Fe doping induced a transformation to a two-dimensional non-layered structure composed of nanosheets, significantly increasing the specific surface area and exposing more active sites. The Fe-doped γ-MnO₂ catalysts were evaluated for the degradation of chlorimiprazole (CBZ), a persistent pollutant, using a sulfate radical-based advanced oxidation process. Among the synthesized catalysts, NF-0.25Fe exhibited superior performance, achieving 93% CBZ removal within 16 min under near-neutral conditions. This exceptional activity was attributed to the optimized morphology, higher low-valence Mn content, and enhanced surface-active oxygen species. Systematic investigations revealed that the catalyst dosage, PMS concentration, and pH critically influenced the catalytic efficiency. This work demonstrates the potential of metal ion modulation in tailoring the structural and catalytic properties of transition metal oxides. The insights gained here provide a robust foundation for designing advanced nanomaterials for environmental remediation and other catalytic applications.