Recycling spent LiFePO4 battery for fabricating visible-light photocatalyst with adsorption-photocatalytic synergistic performance and simultaneous recovery of lithium and phosphorus

• Recycling spent LFP battery as photocatalyst increased its economic value. • The NaFeS 2 showed superior adsorption-photocatalytic synergistic capability. • Adsorption process improved the MB removal rate via accelerating photodegradation. • More than 99.9% of Li and P were simultaneously recovered from spent LFP battery. • Mechanisms of NaFeS 2 synthesis and adsorption-photocatalytic synergy were proposed. Converting spent LiFePO 4 (LFP) battery into photocatalysts is an attractive approach for efficiently enhancing the economic profit of recycling low value-added battery. In the current research, a facile and novel strategy for recycling spent LFP battery to fabricate visible-light photocatalyst (NaFeS 2 ) with adsorption-photocatalytic synergistic ability was developed, and more than 99.9% Li and P were simultaneously recovered. The synthesized NaFeS 2 showed superior adsorption-photocatalytic synergistic capability, which could quickly photodegrade 98% methylene blue (MB) without pre-adsorption in 20 min (C 0 =20 mg/L, V=100 mL), and the degradation rate constant of MB by NaFeS 2 was 67 times higher than that of TiO 2 . Mechanisms study demonstrated the enhanced absorption of visible light and efficient charge separation endowed NaFeS 2 with outstanding photocatalytic ability. The excellent adsorption capacity of NaFeS 2 for MB (129.3 mg/g) was ascribed to the electrostatic interaction between negative S 2- /S 2 2- and positively charged MB molecules and coordination interaction between MB molecules and Fe (II)/Fe (III). The synergy of adsorption and photocatalysis shortened the time required for MB to contact with ·O 2 - , ·OH and h + , increasing the degradation rate of MB. In addition, cycle experiments demonstrated NaFeS 2 possessed excellent reusability and stable photocatalytic ability. The current research provides a profitable strategy for recycling low value-added spent LFP battery, and the synthesized NaFeS 2 has potential for industrial application in site remediation with serious pollution of organic dyes.