Revealing Intrinsic Relations Between Cu Scales and Radical/Nonradical Oxidations to Regulate Nucleophilic/Electrophilic Catalysis

Copper/carbon catalysts under different electron-transfer regimes can evolve both radical and nonradical pathways in peroxide activation. However, the underlying trigger to manipulate the transition in between is unclear. Herein, it is revealed that Cu species in a state of sub-nanometre particles (SNPs, < 1 nm) exhibits an electrophilic nature, which is opposite to its nucleophilic nature at a larger scale (nanoclusters, > 1 nm). This switch between nucleophile/electrophile nature leads to distinct catalytic mechanisms in activating peroxymonosulfate, i.e., nonradical ¹O₂ surface-bound upon Cu SNPs and unleashed radical ^•OH induced by Cu nanoclusters. The vacancy defects of biomass-derived carbon can stabilize Cu SNPs via a Cu-V-C configuration, circumventing the contemporary difficulties in coordinating/preserving Metal-N-C bonding. Depth profiling, chemical probes, and charge density difference modeling support the regulable electroactive nature over modulated Cu scales. This featured system is applied for tetracycline degradation, and Cu SNPs demonstrates the highest efficacy with their better peroxymonosulfat confinement in nonradical regime (88.9% removal, nucleophilic activation). Comparatively, severe Cu leaching caused by radical erosion (44.8% removal, electron-donation) is undesirable. Overall, a regulable heterogeneous catalysis is unraveled over carbon-supported Cu sites through scaling modulation and defect engineering. This study illuminates a promising path for customizing biomass-derived Cu-based catalysts to achieve versatile catalysis.