Sulfide/Air Fuel Cell for Sulfur Recycling from Sulfide-Containing Wastewater

It is preferred to recycle resources and energy from pollutants rather than simply remove them. An energy-free concept for sulfide-containing wastewater utilization is presented here. The two-electron route electro-oxidation of sulfide to sulfur cooperates with the four-electron route oxygen reduction reaction to operate as an abiotic sulfide/air fuel cell. It can recycle sulfur and energy from sulfide-containing wastewater in the meantime. Two types of prototypes are fabricated, where both air-aerated cathode and air-breathing cathode are applied. Here, the fuel cell can achieve an open cell voltage of 0.41 V, a maximum discharge current density of 20.03 mA cm–2, and a maximum power density of 0.90 mW cm–2. A real spent caustic stream is used as the sulfide-containing wastewater. For the sulfide-containing wastewater treatment, the fuel cell can achieve a stable, self-driven discharge at ≥10 mA cm–2, where an air-aerated cathode is applied. The formation of sulfur can be observed. This work presents an attractive strategy for sulfide-containing wastewater reclamation.