| Title |
The pH Dependence of MoS2 on Electrocatalytic Activity for Hydrogen Evolution Reaction in Alkaline Media |
| Authors |
신민지(Min Ji Shin) ; 정문근(Simon MoonGeun Jung) ; 정원석(Won Suk Jung) |
| DOI |
https://doi.org/10.3365/KJMM.2026.64.7.628 |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
Alkaline water electrolysis; Hydrogen evolution reaction; Non-precious metal catalyst; Dichalcogenide; Hydrothermal synthesis |
| Abstract |
MoS2 has emerged as a promising non-precious electrocatalyst for the hydrogen evolution reaction (HER) because of its tunable electronic structure, layered architecture, and abundant catalytically active edge sites. In this study, we systematically investigate how the precursor-solution pH during hydrothermal synthesis governs the morphology, phase composition, and alkaline HER performance of MoS2 in 1 M KOH. MoS2 catalysts were synthesized at pH 1.5, 3.5, 5.2, and 7.5 under otherwise identical reaction conditions in order to isolate the influence of pH. The results showed that a uniform nanoflower architectures assembled from well-aligned nanosheets were formed at lower pH, but at high pH, the nanosheets strongly aggregated into a densely stacked spherical structure, causing a sharp decrease in porosity and accessible surface area. XRD confirmed a dominant 2H framework for all samples, while XPS revealed that the metallic 1T-Mo4+ fraction was maximized at pH 1.5 and decreased with increasing pH. Electrochemical measurements demonstrated that the MoS2 catalyst prepared at pH 1.5 exhibited the lowest overpotential at a current density of 10 mA cm-2, the smallest Tafel slope, and the highest double-layer capacitance. The catalytic activity was largely retained after 1,000 potential cycles. These findings demonstrate that simple pH control during hydrothermal synthesis is an effective strategy for simultaneously tailoring the nanostructure and near-surface phase composition of MoS2, thereby improving its electrocatalytic performance for alkaline HER. |