High-Entropy Sulfide Catalyst Boosts Energy-Saving Electrochemical Sulfion Upgrading to Thiosulfate Coupled with Hydrogen Production.

ABSTRACT

Electrochemical sulfion oxidation reaction (SOR) offers a sustainable strategy for sulfion-rich wastewater treatment, which can couple with cathodic hydrogen evolution reaction (HER) for energy-saving hydrogen production. However, the corrosion and passivation of sulfur species render the inferior catalytic SOR performance, and the oxidation product, polysulfide, requires further acidification to recover cheap elementary sulfur. Here, we reported an amorphous high-entropy sulfide catalyst of CuCoNiMnCrSx nanosheets in situ growth on the nickel foam (CuCoNiMnCrSx/NF) for SOR, which achieved an ultra-low potential of 0.25 V to afford 100 mA cm-2, and stable electrolysis at as high as 1 A cm-2 for 100 h. These were endowed by the manipulated chemical environments surrounding Cu+ sites and the constructed "soft-acid" to "hard-acid" adsorption/desorption sites, enabling synergistically boosted adsorption/desorption process of sulfur species during SOR. Moreover, we developed an electrochemical-chemical tandem process to convert sulfions to value-added thiosulfate, providing a good choice for simultaneous wastewater utilization and hydrogen production.