Electrocatalytic properties of biomimetic supported incomplete cubane-type [Mo3S4](4+) clusters are investigated. The activity toward the hydrogen evolution reaction (HER) is evaluated on both a high surface area gas diffusion electrode in a membrane electrode assembly and on highly orientated pyrolytic graphite (HOPG) supports. Sub-monolayers of the clusters were imaged by means of scanning tunnelling microscopy (STM) prior to electrochemical characterization. This enabled the quantification of the activity on a per cluster basis for the HER and the comparison of the activity with other HER catalysts. We find that the HER activity of the [Mo3S4](4+) is comparable with that of the edge sites of MoS2. The supported [Mo3S4](4+) molecules were also characterized by X-ray photoelectron spectroscopy (XPS), and the observed deterioration in electrocatalytic activity with time was assigned to slow [Mo3S4](4+) cathodic desorption from the catalyst support.
Jaramillo, T., Bonde, J. L., Zhang, J., Ooi, B. L., Andersson, K. J., Ulstrup, J., & Chorkendorff, I. (2008). Hydrogen Evolution on Supported Incomplete Cubane-type [Mo3S4](4+) Electrocatalysts. Journal of Physical Chemistry C, 112(45), 17492-17498. https://doi.org/10.1021/jp802695e