Interface-engineered ZnS QDs@HKUST-1 composite for electrochemical overall water splitting

The global demand for sustainable hydrogen production continues to accelerate as hydrogen emerges as a cornerstone of the carbon-neutral energy economy. Water splitting provides a clean and scalable pathway for green hydrogen production and sustainable energy development; however, its efficiency is constrained by sluggish reaction kinetics and a lack of catalysts that can simultaneously deliver high activity, stability, and structural tunability, an area that remains scantly explored. Here, we report a ZnS QDs@HKUST-1 (ZQH-1) composite, synthesized via a bottle-around-the-ship strategy, as a high-performance bifunctional electrocatalyst for overall water splitting. The synergistic integration of ZnS QDs and HKUST-1 MOF enhances conductivity, strengthens charge interactions, and increases the exposure of metal active sites. Consequently, ZQH-1 achieves low overpotentials of 106 mV for the OER and 140 mV for the HER at 10 mA cm^-2, alongside excellent durability over 36 h at 10 mA cm^-2, enabling overall water splitting at only 1.78 V. The physicochemical properties of ZQH-1 were systematically studied using various analytical techniques to investigate its structural features, morphology, chemical composition, and specific surface area. This work demonstrates how interfacial charge dynamics and active-site accessibility govern the catalytic performance of QDs@MOF composites and establishes a general strategy for designing efficient, durable, and low-cost electrocatalysts for sustainable hydrogen production.