(324b) Correlating Material Properties of MoS2 Thin Films with Activity and Stability Crucial to Long-Term Operation in Photoelectrochemical Devices

Photoelectrochemistry (PEC) represents a sustainable approach to produce hydrogen (H₂) on demand. However, significant optimization of these devices is required for them to become competitive to current industrial H₂ production, including the development of new catalyst materials. Since a photoelectrode is in direct contact with the electrolyte, problems associated with corrosion arise, and are further aggravated by submitting a PEC device to real-world operating conditions including changes in temperature and illumination intensity throughout the day/ year.^[1]

MoS₂ is an earth-abundant layered catalyst material that can efficiently act as both protective coating and catalyst, which allows for long-term operation on the order of weeks to months.^[2] To improve the stability of photoelectrodes using MoS₂, more insights are needed to understand dissolution mechanisms – especially under diurnal conditions. In this work Mo thin films were deposited on Si using physical vapor deposition, followed by sulfidation with H₂S. Since both activity and stability of MoS₂ depend on the number of edge sites, the crystallinity of the MoS₂ thin films was varied through changes in the sulfidation temperature and time. Performance and durability were characterized via cyclic voltammetry, inductively coupled plasma mass spectrometry, and electrochemical mass spectrometry, and correlated to material properties such as surface morphology, crystal phases, and crystallinity. This allows for a comparative analysis of structure-activity-stability relationships, and thus the development of optimum synthesis conditions. Ultimately, the question is if it is possible to prepare photoelectrodes using MoS₂ for long-term real-world PEC application.

[1] K. M. K. Yap, S. A. Lee, T. A. Kistler, D. K. Collins, E. L. Warren, H. A. Atwater, T. F. Jaramillo, C. Xiang, A. C. Nielander, 2024, 1–11.

[2] L. A. King, T. R. Hellstern, J. Park, R. Sinclair, T. F. Jaramillo, ACS Appl. Mater. Interfaces 2017, 9, 36792–36798.