Superior photoelectrochemical performance of electrodeposited 1T/2H–MoS2 quantum dots for hydrogen evolution

A facile and scalable strategy is reported for green hydrogen production via pulsed electrodeposition of MoS 2 quantum dots (QDs), exploiting their high surface-to-volume ratio and intrinsic catalytic activity. The synthesized QDs exhibit a mixed-phase structure comprising both the metallic 1T and semiconducting 2H polymorphs of MoS 2 , which synergistically promote charge carrier mobility and interfacial charge transfer while ensuring electrochemical stability under prolonged operation. Structural and compositional analyses, including X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and high-resolution transmission electron microscopy, confirm the coexistence of 1T and 2H phases. Photoelectrochemical impedance spectroscopy and photocurrent response measurements demonstrate excellent catalytic performance, with a photocurrent density of −30 mA cm −2 at −0.5 V vs. RHE, a low onset potential of 42 mV, a small Tafel slope of 90 mV·dec −1 , and minimal overpotential requirements. Notably the 1T/2H–MoS 2 QDs catalyst exhibit robust photoelectrochemical stability and achieve a high hydrogen evolution rate of 1700 μmol L −1 ·h −1 outperforming or matching the efficiency of state-of-the-art MoS 2 -based catalysts. These results position hybrid-phase MoS 2 QDs as a promising next-generation electrocatalyst for efficient and sustainable hydrogen evolution applications.