Boosting Hydrogen Evolution Kinetics with MoS₂-Decorated TiO₂ Nanotubes

The development of efficient and durable nonplatinum-based electrocatalysts for the hydrogen evolution reaction (HER) remains a key challenge. This study explores the heterojunction between titanium dioxide nanotubes (TiO₂ NTs) and molybdenum disulfide quantum dots (MoS₂ QDs) as a viable alternative to platinum-based HER electrocatalysts. TiO₂ NTs were synthesized via anodization, while MoS₂ QDs were electrosynthesized chronopotentiometrically, followed by heterojunction formation via immersion/adsorption. The optimized TiO₂ NTs/MoS₂ QDs electrocatalyst exhibited significantly enhanced HER activity, achieving an overpotential of 617 mV at 100 mA cm^-2 (η¹⁰⁰), a notable improvement over 927 mV observed for bare TiO₂ NTs. Electrochemical impedance spectroscopy (EIS) revealed a dramatic reduction in charge transfer resistance from 475 to 9.9 Ω after MoS₂ QDs deposition. A Tafel slope of 106 mV dec^-1 indicated a Volmer-Heyrovsky HER mechanism with second-order kinetics, as confirmed by kinetic modeling. Structural and morphological characterization (XRD, SEM, TEM, and EDX) confirmed the successful heterojunction formation. This work highlights the potential of TiO₂ NTs/MoS₂ QDs as scalable and efficient electrocatalysts for sustainable hydrogen production, offering a promising alternative to platinum-based systems.