Hydrothermal Synthesis of Nonintercalated Phase-Pure 1T-MoS2 for Hydrogen Evolution

Over the past 15 years, the hydrothermal (HT) synthesis of MoS 2 has been immensely pursued due to its promising application in electrocatalytic hydrogen evolution reaction (HER). However, a systematic study of the effect of different reaction parameters such as the reactant amount, the solution volume, the reaction temperature, and the time on the 2H/1T-phase evolution in MoS 2 has not yet been conducted . In this work, we screened MoS 2 synthesized at different reaction parameters for its HER activity. X-ray photoelectron spectroscopy, X-ray diffraction, and thermal analysis revealed that phase-pure 1T-MoS 2 (M3S15), devoid of any foreign ion/molecule in the interlayer, is formed at an optimized reaction condition, which has not been realized in the HT synthesis till date. M3S15 showed the highest HER activity with an η 10 value of 222 mV, Tafel slope of 63 mV dec –1, turnover frequency of 0.11 s –1, exchange current density ( j 0 ) of 9.12 μA cm –2, and R CT of 130 Ω. The work further demonstrates a simple one-step method in which M3S15 is ultrasonicated without the use of any additives to obtain a stable dispersion of single-layer 1T-MoS 2 (PS-M3S15). The electrocatalytic HER studies showed enhanced activity of PS-M3S15 with η 10 = 198 mV and Tafel slope = 58.7 mV dec –1 . The high HER operational stability of M3S15 is reflected in 20 h chronoamperometry and 3000 continuous potential cycle studies. The structure and morphology of the postchronoamperometry sample remain unchanged, but the activity of M3S15 decreases on storage at room temperature.