Interface-Engineered ZnS QDs@HKUST-1 Composite for Electrochemical Overall Water Splitting

Abstract

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, but its efficiency is constrained by sluggish reaction kinetics and the lack of catalysts, as this area remains scantly explored, that can simultaneously deliver high activity, stability, and structural tunability. Here, we report a ZnS QDs@HKUST-1 (ZQH-1) composites, 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 OER and 140 mV for 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.