Spent LiFePO4: An old but vigorous peroxymonosulfate activator for degradation of organic pollutants in water.

Iron-based catalysts have been demonstrated to activate peroxymonosulfate (PMS) to generate reactive radicals, which is however limited by their complex preparation process, high costs and inefficiency for practical applications. Herein we obtain spent LiFePO4 (SLFP), with powerful catalytic capacity by a simple one-step treatment of the retired LiFePO4 cathode material, for PMS activation to decontaminate organic pollutants. Lithium defects and oxygen vacancies in SLFP play critical roles for PMS utilization, further confirmed by density functional theory (DFT) calculations. SLFP materials rapidly adsorb PMS, and the surface PMS is activated by Fe(II) to generate radicals, with •OH playing a major role for the degradation of organics after multi-step reactions. The SLFP/PMS process is finally validated for ability to remove organic contaminants and potential environmental application.