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  Shen, C.; Wierzbicka, E.; Schultz, T.; Wang, R.; Koch, N.; Pinna, N.: Atomic Layer Deposition of MoS₂ Decorated TiO₂ Nanotubes for Photoelectrochemical Water Splitting. Advanced Materials Interfaces 9 (2022), p. 2200643/1-10

10.1002/admi.202200643
Open Access Version

Abstract:
A thermal atomic layer deposition (ALD) process to fabricate MoS2 thin films is successfully demonstrated by using cycloheptatriene molybdenum tricarbonyl (C7H8Mo(CO)3) and H2S as precursors at an ALD temperature below 300 °C. The process is systematically investigated, showing a typical self-limiting characteristic within an ALD temperature window of 225–285 °C and a high growth-per-cycle of 0.11 nm. The as-deposited films are amorphous while they can be crystallized in situ by sulfurization with H2S at a low temperature of 300 °C. A prototypical application of the developed ALD process is demonstrated by constructing a MoS2/TiO2 heterostructure through depositing MoS2 onto anodized TiO2 nanotubes for photoelectrochemical water splitting. The MoS2/TiO2 heterostructures exhibit approximately three times superior photoelectrochemical performance than the pristine TiO2 nanotubes. This is attributed to an enhanced visible light-harvesting ability of MoS2 and an improved separation of the photo-generated charge carriers at the heterostructure interface, which is affirmed by a staggering gap (type II) between MoS2 and TiO2 as probed by ultraviolet photoelectron spectroscopy.