Electrochemical Modulation of MoS 2 Structures to Boost Hydrogen Evolution Reaction Efficiency

The use of molybdenum disulfide (MoS 2 ) as a non‐noble metal electrocatalyst for the hydrogen evolution reaction (HER) has gained significant attention due to its affordability and the ease of modifying factors such as voltage, current, duration, and the composition and concentration of the electrolyte solution using electrodeposition techniques. To increase the number of active sites on the surface of MoS 2 , fine nanoscale tailoring of the crystalline phase is necessary. This can be accomplished using electrochemical phase formation. In this study, four types of MoS 2 nanoparticles are successfully electrodeposited on copper foil substrates using a mixture of Na 2 MoO 4 and Na 2 S electrolytes, namely fine nodular MoS 2 (FNMoS 2 ), small sheet MoS 2 (SSMoS 2 ), highly porous MoS 2 (HPMoS 2 ), and low porous MoS 2 (LPMoS 2 ), with nanoparticles of FNMoS 2 , SSMoS 2 , HPMoS 2 , and LPMoS 2 being produced at potentials of −0.9, −1.0, −1.1, and −1.2, respectively. The electrochemical performance of these nanoparticles on HER is carefully investigated using techniques such as high‐resolution transmission electron microscopy (HRTEM), X‐ray diffraction (XRD), and energy dispersive spectroscopy. Linear sweep voltammetry, Tafel plot analysis, and electrochemical impedance spectroscopy are used to study the electrocatalytic performance of HER in a 0.5 M KOH electrolyte. HPMoS 2 electrodeposited at −1.1 V for 200 s had a HER current density of 10 mA cm −2 at η = −270 mV and a Tafel slope (vs RHE) of 35.8 mV/dec, lower than that of FNMoS 2 , SSMoS 2 , and LPMoS 2 . These results have significant implications for the development of low cost, affordable, and environmentally friendly electrochemical methods of producing hydrogen, and pave the way for further research in this field.