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[Display omitted] • We propose a rejuvenation recipe for SLFP in applied environmental catalysis. • SLFP exhibits enhanced reactivity than pristine one in the activation of S(IV). • Li defects and oxygen vacancies are key to unexpected reactivity of SLFP. Lab-prepared Fe-bearing materials have demonstrated their ability to activate sulfite (S(IV)) to generate reactive radicals, which is however limited by their costs and inefficiencies for practical application. Here we report that spent LiFePO 4 (SLFP) cathode materials can function as a robust catalyst for S(IV) activation and consequent decontamination of organic pollutants like 4,4′-sulfonyldiphenol (BPS). Unexpectedly, SLFP materials with lithium defects and oxygen vacancies (O v) are significantly effective than pristine LiFePO 4. BPS degradation undergoes an induction period when rapid adsorption of O 2 and HSO 3 − in water occurs, followed by a slow release of HSO 5 −, as evidenced by the same depletion trends of BPS and sulfite, and confirmed by theoretical calculations. The HSO 5 − is activated by Fe(II) on the SLFP surface, with •OH being the main reactive species via a multi-step reaction. The potential environmental application of this SLFP/S(IV) process are evaluated ultimately. [ABSTRACT FROM AUTHOR]

[Display omitted] • We propose a rejuvenation recipe for SLFP in applied environmental catalysis. • SLFP exhibits enhanced reactivity than pristine one in the activation of S(IV). • Li defects and oxygen vacancies are key to unexpected reactivity of SLFP. Lab-prepared Fe-bearing materials have demonstrated their ability to activate sulfite (S(IV)) to generate reactive radicals, which is however limited by their costs and inefficiencies for practical application. Here we report that spent LiFePO 4 (SLFP) cathode materials can function as a robust catalyst for S(IV) activation and consequent decontamination of organic pollutants like 4,4′-sulfonyldiphenol (BPS). Unexpectedly, SLFP materials with lithium defects and oxygen vacancies (O v) are significantly effective than pristine LiFePO 4. BPS degradation undergoes an induction period when rapid adsorption of O 2 and HSO 3 − in water occurs, followed by a slow release of HSO 5 −, as evidenced by the same depletion trends of BPS and sulfite, and confirmed by theoretical calculations. The HSO 5 − is activated by Fe(II) on the SLFP surface, with •OH being the main reactive species via a multi-step reaction. The potential environmental application of this SLFP/S(IV) process are evaluated ultimately. [ABSTRACT FROM AUTHOR]

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 LiFePO 4 (SLFP), with powerful catalytic capacity by a simple one-step treatment of the retired LiFePO 4 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. • SLFP was an old but vigorous PMS activator for decontamination. • Surface defects of SLFP play a key role in PMS activation. • Quenching experiment and DFT calculation were used to reveal mechanism. • This proposed SLFP/PMS process was environmental benign. [ABSTRACT FROM AUTHOR]