Preparation of bifunctional electrocatalyst by recycling heavy metal ions from wastewater using EDTAD-functionalized MOF as highly efficient adsorbent

The recovery and subsequent reuse of heavy metal ions from industrial wastewater are crucial for promoting sustainable development, but they also present significant challenges. In this article, ethylenediaminetetra-acetic dianhydride (EDTAD), which possesses strong metal chelating ability, is covalently attached to MIL-101-NH₂ (Fe), resulting in a significant improvement in the removal rate of heavy metal ions in wastewater. Furthermore, the recovered waste metal ions are transformed into high-performance FeNi₃/NiFe₂O₄@NC dual-functional oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalysts. Specifically, FeNi₃/NiFe₂O₄@NC exhibits outstanding OER performance, with only a 264 mV overpotential at 10 mA·cm⁻². Density functional theory (DFT) calculations reveal that the synergistic effect of the FeNi₃/NiFe₂O₄@NC heterostructure can enhance conductivity, optimize the free energy of * to OH* during OER reaction, and promote catalytic reactivity. This work not only improves the removal rate of heavy metal ions but also obtains high-performance catalysts, while providing a new approach for the treatment and secondary utilization of heavy metal ion wastewater as well as the preparation of low-cost catalysts.