Photo-Oxidation Coupled Ion Intercalation for Sustainable Heavy Metal Removal and Resource Recovery

Abstract

Developing innovative and efficient methods for heavy metal removal and resource recovery is crucial for advancing sustainable environmental remediation and resource management. Herein, a novel photoelectrochemical (PEC) system is presented that couples photo-oxidation with ion intercalation to achieve Pb(II) immobilization, removal, and recycling. This single-chamber, membrane-free PEC process integrates a titanium dioxide photoanode with abundant oxygen vacancies (TiO₂-Ov) and a Prussian Blue analogue (PBA) cathode, enabling enhanced photogenerated charge separation and transfer under solar irradiation. At the photoanode, Pb(II) is oxidized to Pb(IV), forming stable PbO₂ deposits, while the PBA cathode simultaneously confines Pb(II) ions through ion intercalation. This coupled pathway capitalizes on Pb(II)’s redox potential, achieving over 90% removal efficiency under mild conditions without secondary pollution. The system also facilitates real-time detection of lead contamination via a distinct color change at the photoanode, enhancing its practical applicability. Additionally, the recovered Pb(II) is converted into high-purity PbI₂, a valuable material for perovskite solar cells, bridging environmental remediation with resource recovery. This PEC process offers a sustainable and scalable solution for heavy metal management, with significant implications for environmental chemistry, circular economy practices, and industrial sustainability.