Energy-Positive Thiosulfate Production Enabled by Coupling Waste Sulfide Oxidation with Oxygen Reduction

Electrochemical sulfide oxidation offers a promising route for sulfur recovery, but conventional systems are typically energy-intensive and produce low-value products. Here we develop a galvanic electrochemical-chemical cascade strategy that couples the sulfide oxidation reaction (SOR) with the two-electron oxygen reduction reaction (ORR), enabling sulfide valorization with net positive electrical energy output.

Specifically, a Ce-modified Cu₂S anode is designed to enhance both SOR activity and selectivity. Ce incorporation electronically modulates the Cu–S framework, providing a favorable intrinsic pathway for deeper sulfide oxidation and sulfur-chain propagation, while the resulting polysulfide distribution is further governed by the electrochemical reaction conditions. The optimized Ce–Cu₂S/NF electrode achieves 100 mA cm^–2 at 0.28 V versus the reversible hydrogen electrode and maintains stable SOR operation for over 110 h.