Bifunctional Cobalt-Nickel Sulfide Nanoflowers as Electrocatalysts for Concurrent Energy-Efficient Hydrogen Production and Sulfur Recycling

Electrocatalytic water splitting is an important approachfor sustainableand green production of hydrogen but is greatly hampered by the sluggishoxygen evolution reaction (OER). Therefore, developing a favorablealternative reaction to replace OER for both energy-efficient coproductionof hydrogen and value-added chemicals is highly desirable. Herein,a thermodynamically favorable sulfion oxidation reaction (SOR) electrocatalyzedby CoNi2S4 nanoflowers (CoNi2S4 NFs) is reported to couple with the hydrogen evolution reaction(HER) for energy-efficient hydrogen production and sulfur recovery.In this coupled system, only a low cell voltage of 0.3 V is requiredto produce hydrogen at 10 mA cm(-2), much lower thanthat of water splitting (1.76 V). Meanwhile, S2- ions are selectively electrooxidized to sulfur with a high yieldof 220.5 g h(-1) m(-2), realizingelectrochemical upcycling of sulfur-containing pollutants. This strategyprovides an attractive route for both energy-effective hydrogen generationand sulfur recycling.