Surfactant-exfoliated 2D molybdenum disulphide (2D-MoS2): the role of surfactant upon the hydrogen evolution reaction

Abstract

Surfactant (sodium cholate, SC) mediated liquid (aqueous) phase exfoliation is a common approach to fabricate 2D molybdenum disulphide (2D-MoS₂–SC) nanosheets since it is a facile methodology producing defect free flakes with nanometer lateral sizes. The electrocatalytic behaviour of 2D-MoS₂–SC towards the Hydrogen Evolution Reaction (HER) is benchmarked within acidic media and found to exhibit inferior HER activity to an equivalent mass of pristine 2D-MoS₂ (2D-MoS₂ produced without a surfactant), with HER onset potentials, current densities and Tafel values of −0.61 V (vs. SCE), −2.19 mA cm⁻², 141 mV dec⁻¹ and −0.42 V (vs. SCE), −4.96 mA cm⁻², 94 mV dec⁻¹ respectively. This work demonstrates that sodium cholate has a detrimental effect upon the HER activity of 2D-MoS₂. Future studies that utilise 2D materials, fabricated via liquid surfactant exfoliation, should consider the role of the surfactant in the observed electrochemical responses and perform the necessary control experiments.