Bridging Lead Remediation and CO2 Upgrading through Targeted Cation Exchange in an Ellagic Acid-based MOF

Abstract

Addressing heavy-metal pollution and anthropogenic CO₂ emissions simultaneously represents a formidable challenge. Herein, we report a closed-loop "waste-to-wealth" strategy that couples Pb²⁺ remediation with electrocatalytic CO₂ upgrading using SU-102, a stable metal-organic framework (MOF) constructed from biomass-derived ellagic acid. SU-102 exhibits an exceptional intrinsic affinity for sequestering Pb²⁺ directly from highly acidic simulated industrial wastewater. Rather than generating hazardous secondary waste, this targeted cation-exchange process seamlessly transforms the pollutant-loaded matrix into SU-102-Pb, a structurally precise electrocatalyst with Pb²⁺ uniformly tethered to oxygen-rich nodes. These captured Pb ions act as isolated catalytic centres for CO₂ reduction, delivering a state-of-the-art HCOO⁻ Faradaic efficiency of 96.5% at -0.98 V vs. reversible hydrogen electrode (RHE) and maintaining >80% selectivity across a broad 600-mV window. In situ spectroscopy mechanistically validates that these rationally engineered sites drive the reaction exclusively via a favorable *OCHO intermediate pathway. Scalable to the gram level using actual wastewater matrices, SU-102-Pb represents one of the highest-performing Pb-based MOF electrocatalysts reported to date. This work provides a compelling, sustainable blueprint for valorising toxic environmental pollutants into high-value functional materials for clean energy conversion.