Sulfur-mediated electrochemical copper recovery from wastewater with net electricity generation

The extensive mining and processing of copper (Cu) generate substantial amounts of wastewater containing Cu. The toxicity of these streams and the rapidly growing global demand for copper underscore the urgent need for reliable Cu recovery strategies. Conventional approaches suffer from low Cu extraction efficiency, poor selectivity and the formation of low-value Cu products. Here we describe a sulfur (S)-mediated electrochemical strategy for efficient Cu recovery from wastewater with the co-generation of electricity. Leveraging the reversible S → Cu2S conversion, the S electrode acts as a redox mediator, achieving high Cu extraction capacity, excellent Cu2+ selectivity and robust reusability. By coupling with a sacrificial iron electrode, a two-chamber device enables continuous Cu extraction from wastewater while simultaneously producing electricity. The extracted Cu2+ is subsequently recovered in a secondary deposition cell, yielding high-value metallic Cu. A flow-type cell demonstrates stable operation with real wastewater over ~250 h with a cumulative electricity output of 1.00 kWh m−2 and Cu recovery of 2.02 kg m−2. Life cycle assessment and life cycle costing indicate favourable environmental and economic performance, thus highlighting the strong potential of the system for scalable deployment