A green strategy to synthesize two-dimensional lead halide perovskite via direct recovery of spent lead-acid battery

Hybrid organic-inorganic perovskite is a class of emerging materials with promising application prospects in optoelectronics. However, the consumption of lead resources and poor stability in moisture environment have limited their practical applications. Herein, a family of air-stable two-dimensional (2D) hybrid organic-inorganic perovskite crystal (C₄H₉NH₃)₂PbX₄ (X=Cl, Br, I or mixed halides of them) is efficiently synthesized by direct recovery of spent lead-acid battery (LAB) paste. More than 95 wt% of the total lead element in spent lead paste could be recovered and converted into low-impurity lead ion solution via a facile recovery process at room temperature. Then 2D hybrid perovskite crystal is synthesized from the recovered lead ion solution with a one-pot solvent evaporation method. Excellent air stability is observed for the prepared perovskite crystals after exposure in high-humidity air at a high temperature of 75 °C, attributing to its layered structure which is capped with long-chain hydrophobic alkyl groups. The emission wavelengths of the synthesized perovskite crystals are tunable from 380 to 560 nm (corresponding to visible purple to yellow light) by compositional modulations, demonstrating their potential applications as optoelectronic materials. This research has proposed a promising strategy to synthesize high-value 2D hybrid perovskite optoelectronic materials directly recovered from spent LAB.