Hydrothermal synthesis of 2D MoS2 nanosheets for electrocatalytic hydrogen evolution reaction

Abstract

Nanostructured molybdenum disulfide (MoS₂) is a very promising catalyst for producing molecular hydrogen by electrochemical methods. Herein, we have designed and synthesized highly electocatalytically active 2D MoS₂ nanosheets (NS) from molybdenum trioxide (MoO₃) by a facile hydrothermal method and have compared their electrocatalytic activities for hydrogen evolution reaction (HER). The electrochemical characterization was performed using linear sweep voltammetry (LSV) in acidic medium. The MoS₂ NS show a HER onset potential at about 80 mV vs. reversible hydrogen electrode (RHE) which is much lower than MoO₃ (300 mV). The MoS₂ NS and MoO₃ show a current density of 25 mA cm⁻² and 0.3 mA cm⁻², respectively at an overpotential of 280 mV vs. RHE. The MoS₂ NS showed an 83 times higher current density when compared to MoO₃. The Tafel slopes of the MoS₂ NS and MoO₃ were about 90 mV per dec and 110 mV per dec respectively. This suggests that MoS₂ NS are a better electrocatalyst when compared to MoO₃ and follow the Volmer–Heyrovsky mechanism for HER.