Magnetic-directed closed-loop lead recycling from spent perovskite photocatalysts toward sustainable CO2 reduction

Abstract

Development of efficient lead recycling processes for spent perovskite photocatalysts is crucial for mitigating environmental risks associated with lead toxicity. In this study, we present a cost-effective, magnetic-directed closed-loop strategy for sustainable lead recovery from spent CsPbBr₃-based photocatalysts. Magnetic CoFe₂O₄ serves a dual purpose: as a cocatalyst to form a CsPbBr₃/CoFe₂O₄ heterojunction for efficient photocatalytic CO₂-to-C₂ conversion with 92.54% selectivity toward ethanol, and as a magnetic handle to enable facile separation. After the catalytic reaction, the spent CsPbBr₃/CoFe₂O₄ composite is magnetically collected and dissolved in dimethyl sulfoxide (DMSO), allowing the insoluble CoFe₂O₄ support to be removed in situ with a magnet. The leachate containing Pb²⁺ and Cs⁺ ions undergoes multi-cycle adsorption on a cation exchange resin, followed by gradient-acid elution, pH adjustment, and selective precipitation to yield high-purity PbBr₂. This recovered PbBr₂ is directly used to resynthesize CsPbBr₃-based catalysts, which retain comparable activity to fresh counterparts over five cycles. This integrated approach achieves a lead recovery efficiency of 94.95%, establishing a closed-loop system that enables repeated cycles of catalyst use, lead recovery, and material regeneration.