Solar-Driven Synchronous Photoelectrochemical Sulfur Recovery and Pollutant Degradation

Hydrogen sulfide (H₂S) is a hazardous contaminant in many industrial gases and wastewaters and a potential source of sulfur to be recovered, but effective and sustainable recovery technologies are still lacking. Here, we report a novel photoelectrochemical process for synchronous sulfur recovery and removal of organic pollutant, which typically coexist in waste streams, by using solar-simulating light as the sole driving force. In this system, sulfide was selectively converted into high-purity elemental sulfur (S⁰) particles at the photoanode, whereas efficient electrochemical oxidation of carbamazepine occurred at the cathode through Fe²⁺/Fe³⁺-mediated peroxymonosulfate activation. The formed sulfur particles with initial sizes of below one micrometer gradually grew into larger particles. Iodine ions were used as anodic redox mediator to favor a selective S⁰ production in the solution over the formation of sulfite/sulfate at the electrode surface. The practical feasibility of this system was demonstrated by using carbamazepine-spiked lake water samples. Our work suggests a great opportunity for sustainable recovery of sulfur resource with concomitant benefits of pollutant control by using the inexhaustible solar energy.