Low-valent Cu doping optimizes Ruddlesden-Popper perovskite for accelerated levofloxacin removal: Enhanced Ni-dominated dual radical/nonradical pathways

Ruddlesden-Popper (R-P) perovskites have emerged as superior candidates for peroxymonosulfate-based advanced oxidation processes (PMS-AOPs) due to their tunable electronic configurations and enhanced electron transfer kinetics. Although metal doping has been extensively studied as the most common catalyst modification strategy in PMS activation processes, systematic identification of the dominant metal species in doped systems remains lacked. In this work, copper-doped R-P perovskite (La_1.2Sr_0.8Ni_0.7Cu_0.3O_4+δ, LSNC_0.3) was employed to investigate the influence of B-site ion electronic environment evolution on reactive oxygen species (ROS) generation during PMS activation, with the dominant metal species being determined through combined density functional theory (DFT) calculations and characterization. LSNC_0.3 demonstrated exceptional activation performance, achieving 94% levofloxacin (LVFX) removal within 30 min (k = 0.0853 min^-1), significantly surpassing undoped La_1.2Sr_0.8NiO_4+δ (LSNO). Cu doping induced anisotropic lattice strain through synergistic Jahn-Teller distortion and B-site dual-metal redox cycling, thereby enhancing oxygen vacancies (OVs) density and enabling dual radical (•OH/•O₂⁻) and non-radical (¹O₂/electron transfer process (ETP)) pathways. DFT calculations revealed that Cumediated downshift of Ni 3d band center (-0.266 eV) optimized PMS adsorption energy (-4.218 eV), confirming Ni's predominant role in this system. LC-MS/DFT analyses identified piperazine cleavage and quinolone oxidation as primary LVFX degradation pathways, with toxicity reduction verified by T.E.S.T. This work provides guidance for designing robust perovskite catalysts in advanced water remediation applications.