Tuning Interlayer Spacing and Lattice Strain in MoS ₂ via Ag Doping for Enhanced Energy Storage and HER Applications

ABSTRACT Herein, a facile one‐pot hydrothermal method was employed to synthesize stable mixed‐phase (1T/2H) MoS ₂ with enhanced metallic character by optimizing thiourea concentration, which activates the basal plane and improves electrochemical performance. Further in‐plane Ag doping induces lattice distortion and crystal strain, enlarges interlayer spacing, and reduces charge‐transfer resistance, thereby enhancing both supercapacitor and hydrogen evolution reaction (HER) performance. As a supercapacitor electrode, Ag‐doped 1T/2H MoS ₂ delivers a high specific capacitance of 1493.5 Fg ⁻¹ at 1 Ag ⁻¹ with an energy density of 552.1 Whkg ⁻¹ , outperforming undoped mixed‐phase MoS ₂ (1119.2 Fg ⁻¹ ). In 1M KOH, Ag‐doped MoS ₂ exhibits superior HER activity, requiring an overpotential of 206 mV to achieve 10 mA cm ⁻² , significantly lower than undoped MoS ₂ (280 mV). The Tafel slope decreases from 226 to 150 mV dec ⁻¹ , and further reduces to 107 mV dec ⁻¹ under illumination, indicating improved reaction kinetics. Overall, the synergistic effect of mixed‐phase engineering and Ag doping significantly enhances the multifunctional electrochemical performance of MoS ₂ for advanced energy storage and hydrogen production applications.