Ethanol introduced synthesis of ultrastable 1T-MoS₂ for removal of Cr(VI)

Metallic 1T phase of MoS₂ (1T-MoS₂) has aroused great concern for decontamination of heavy metal ions from water. Herein, ultrastable 1T-MoS₂ was successfully achieved via a gentle two-stage solvothermal strategy utilizing water and ethanol as solvent for efficient removal of Cr(VI). Notably, nearly 100 % 1T-MoS₂ was obtained, and it remained highly stable in air even for 360 days. Electron paramagnetic resonance analysis showed that sulfur vacancies were in situ formed on the 1T/2H mixed phase MoS₂ (M-MoS₂) under the induction of ethanol, which is critical to promote the transformation of 2H to 1T phase. Molecular dynamic simulation revealed that there was strong interaction between ethanol and MoS₂ surface, which could decrease the total energy of MoS₂ for strengthening stability of 1T phase. Moreover, 1T-MoS₂ shows superior sorption capacity (200.3 mg·g^-1) for removal of Cr(VI), twice more than that of M-MoS₂ and 2H phase MoS₂ under the same condition. Significantly, the stable phase structure of 1T-MoS₂ and chromium adsorption capacity still remained even after five cycles of chromium adsorption. The study of Cr(VI) adsorption mechanism revealed that the chromium adsorption was attributed to the undercoordinated Mo(IV) as active site and coupled with redox reaction during removal process.