Oxygen defect engineering CuO@Pd nanocages sensor array for identification of phenolic antioxidants

Oxygen defect engineering, which precisely modulates the coordination environments and dynamic equilibria of oxygen vacancies (O v ), lattice oxygen (O lat ), and adsorbed oxygen (O ads ), serves as a pivotal strategy for optimizing electronic structures and catalytic pathways in metal oxides and is expected to become a core means to enhance the activity of nanoenzymes. Leveraging optimized component ratios from oxygen defect engineering, we engineered hollow porous nanocages with a distinctive 3D open framework to maximize active site exposure. Controlled reduction reconstructed oxygen species distribution, endowing the material with exceptional peroxidase (POD), oxidase (OXD), and laccase (LAC) activities. Capitalizing on phenolic pollutants' structural features and reducibility, we developed a tri-channel nanozyme sensor array using CuO@Pd nanocages. This system enables efficient oxidative degradation and precise identification of six phenolic compounds through synergistic triple-enzyme catalysis. Transcending the pH limitations of conventional sensors, the array differentiates phenolic analogues across concentrations with broad linear ranges and high sensitivity. This work establishes a direct methodology for modulating nanozyme activity via oxygen defect engineering while elucidating the electron-transfer mechanism in Pd Cu redox cycling.