Recovery of Lead-Zinc Slags to Methyl-Ammonium Lead Tri-Iodide With Single-Atom Fe–N4 Sites for Piezocatalytic Hydrogen Evolution

Lead (Pb)–zinc (Zn) slags contain large amounts of Pb, causing irreversible damage to the environment. Therefore, developing an effective strategy to extract Pb from Pb–Zn slags and convert them into a renewable high-value catalyst not only solves the energy crisis but also reduces environmental pollution. Herein, we present a viable strategy to recycle Pb and iron (Fe) from Pb–Zn slags for the fabrication of efficient methylammonium lead tri-iodide (r-MAPbI₃) piezocatalysts with single-atom Fe–N₄ sites. Intriguingly, atomically dispersed Fe sites from Pb–Zn slags, which coordinated with N in the neighboring four CH₃NH₃ to form the FeN₄ configuration, were detected in the as-obtained r-MAPbI₃ by synchrotron X-ray absorption spectroscopy. The introduction of Fe single atoms amplified the polarization of MAPbI₃ and upshifted the d-band center of MAPbI₃. This not only enhanced the piezoelectric response of MAPbI₃ but also promoted the proton transfer during the hydrogen evolution process. Due to the decoration of Fe single atoms, r-MAPbI₃ showed a pronounced H₂ yield of 322.4 μmol g⁻¹ h⁻¹, which was 2.52 times that of MAPbI₃ synthesized using commercially available reagents. This simple yet robust strategy to manufacture MAPbI₃ piezocatalysts paves a novel way to the large-scale and value-added consumption of Pb-containing waste residues.