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초록

Hydrogen is increasingly recognized as a sustainable energy carrier for mitigating environmental challenges associated with fossil fuels. Electrochemical water splitting, particularly via the hydrogen evolution reaction (HER), enables carbon-free hydrogen production. Platinum (Pt) is the benchmark HER catalyst owing to its outstanding activity. However, its high cost and scarcity hinder large-scale applications, underscoring the need for efficient and economical alternatives. Transition metal dichalcogenides, such as MoS2, offer high surface-tovolume ratios and abundant edge sites but their catalytic performance remains inferior to that of Pt. Herein, we demonstrate a fully ALD-based strategy-ALD growth of vertically oriented MoS2 nanosheets on graphite foil followed by ALD deposition of Pt nanoparticles (cycle-controlled). ALD enables atomic-scale control and conformal functionalization of Pt on MoS2 grown on graphite foil substrates, where structural and chemical characterizations using Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy indicate Pt functionalization and controlled growth. Electrochemical measurements show that Ptfunctionalized MoS2 exhibits substantially enhanced HER activity, achieving lower overpotentials and reduced Tafel slopes compared to pristine MoS2. This work highlights a fully ALD-based and cycle-resolved fabrication approach-ALD-grown MoS2 nanosheets followed by ALD Pt deposition-enabling reproducible control of morphology and Pt chemical-state evolution, while scalability is discussed based on the inherent characteristics of ALD rather than being experimentally demonstrated in the present study.