Ultraefficient Electrocatalytic Hydrogen Evolution from Strain-Engineered, Multilayer MoS 2 .

This paper reports an approach to repurpose low-cost, bulk multilayer MoS for development of ultraefficient hydrogen evolution reaction (HER) catalysts over large areas (>cm). We create working electrodes for use in HER by dry transfer of MoS nano- and microflakes to gold thin films deposited on prestrained thermoplastic substrates. By relieving the prestrain at a macroscopic scale, a tunable level of tensile strain is developed in the MoS and consequently results in a local phase transition as a result of spontaneously formed surface wrinkles. Using electrochemical impedance spectroscopy, we verified that electrochemical activation of the strained MoS lowered the charge transfer resistance within the materials system, achieving HER activity comparable to platinum (Pt). Raman and X-ray photoelectron spectroscopy show that desulfurization in the multilayer MoS was promoted by the phase transition; the combined effect of desulfurization and the lower charge resistance induced superior HER performance.