Short-term cathodic tuning atomic-level S-S interaction of CuS for heavy metal ultrafast detoxication

Transition metal sulfides have demonstrated excellent heavy metal detoxification in previous studies. However, the activity of their S-functional sites is usually not maximized because they are not precisely regulated. Herein, we report a new short-term cathodic tuned CuS crystals (C-tuned CuS) distortion strategy, ultrafast detoxicating over 95% Cr(VI) in 1 min，its detoxification rate was elevated by five orders of magnitude times compared to the untuned one. The high Cr(VI) detoxification performance is mainly attributed to the layered sulfur atoms tuning within series of cathodic potential shown by In-situ Raman. Besides, the four-tuning stages of C-tuned CuS lattice distortion based on the variation of Raman peak height and redshift changes was investigated by density functional theory (DFT) calculations, showing that the S-S bonds was stretched under cathodic tuning, extending from 2.106 to 2.345 Å. The stretched S-S bonds with enhanced polarity and electron activity prevailed the formation of transient Cr-S bonds with Cr(VI), favoring the direct electron transfer without O mediation, thus reducing the Cr(VI) reduction energy barrier. Cathodic tuning CuS crystal distortion, a “Plug and Play” strategy, show a new electron-level microscopic insights into wastewater reduction techniques development. • Ultrashort-time cathodic electrical stimulation activates strong S-S activity in CuS. • The existence of four stages of S-S bond activation stretching is verified. • Two-electron-activated S-S bonds have strong reducing activity toward Cr(VI). • Activated S-S bonds don't need O as an intermediate for electron transfer thus reducing energy barriers.