Optimized expanding of interlayer distance for molybdenum disulfide towards enhanced hydrogen evolution reaction

Adjusting the hydrogen-binding free energy (Delta GH*) of two dimensional (2D) MoS2 by changing the interlayer distance has been an effective strategy to improve the intrinsic activity for hydrogen evolution reaction (HER). Herein, a facile solvothermal access via various ratio of N, N-dimethylformamide (DMF)/H2O has been used to modulate interlayer distance of nanostructured MoS2. With increasing of DMF, the interlayer distance of MoS2 can be expanded to 9.4 angstrom with smaller sizes, which may be derived from intercalation effect of DMF. The certain ratio of DMF/H2O (volume ratio of 19/1, MoS2-D19H1) leads to the largest interlayer distances of 10.0 angstrom and the smallest size of nanospheres with less stacking than counterparts synthesized at other ratios of DMF/H2O. The expanded interlayer distance of MoS2-D19H1 may change electronic structure of active sites for HER, implying the improved Delta GH* and the intrinsic activity of MoS2. The smallest size also suggests the more exposure of active sites for HER. The electro-chemical measurements demonstrate that MoS2-D19H1 shows the best electrocatalytic performances than MoS2 samples synthesized at other ratio of DMF/H2O. This work may provide a promising strategy to tune the interlayer distance of 2D-layered transition metal dichalcogenide for efficient HER. (C) 2017 Elsevier B.V. All rights reserved.