High-Throughput Pb Recycling for Perovskite Solar Cells Using Biomimetic Whitlockite

Pb contamination in aquatic environments causes severe pollution; therefore, harmless absorbents are required. In this study, we report a novel synthesis of whitlockite (WH, Ca₁₈Mg₂(HPO₄)₂(PO₄)₁₂), which is the second most abundant biomineral in human bone, and its application as a high-performing Pb²⁺ absorbent. Hydroxyapatite (HAP) and WH are prepared via a simple precipitation method. The Pb²⁺ absorption performance and mechanism of the synthesized biominerals are investigated in aqueous solutions at neutral pH. The results demonstrate that WH exhibits an excellent Pb²⁺ absorption capacity of 2339 mg g⁻¹, which is 1.68 times higher than the recorded value for HAP. Furthermore, the absorbed Pb²⁺ ions are recycled into high-purity PbI₂. This is employed as a precursor for the fabrication of perovskite solar cells (PSCs), resulting in a conversion efficiency of 19.00% comparable to that of commercial PbI₂ powder (99.99% purity). Our approach provides an efficient way to remove Pb²⁺ ions from water and reuse them in the recycling of PSCs.