Transition metal dichalcogenide catalysts have been shown to exhibit high catalytic activity for a variety of (electro)catalytic reactions, including the hydrogen evolution reaction (HER) and hydrodesulfurization (HDS). While recent work has illuminated active sites for these reactions, it is a challenge to precisely synthesize catalysts with optimal atomic-scale structure for a given catalytic reaction. To achieve this “designer catalyst” ideal, greater understanding of the synthesis and processing of these materials is needed. Here, we investigate the evolution of the atomic-scale structure of MoS2/Ni catalysts during synthesis using in situ transmission electron microscopy (TEM); the addition of Ni to MoS2 is known to improve catalytic properties for the HDS reaction. These experiments involve heating solid-state precursors using a MEMS heating stage in a TEM. Interestingly, we find that small amounts of Ni (~a few mole percent) significantly altered the evolved morphology of MoS2 crystals, with larger crystals forming in the presence of Ni. Furthermore, crystallization temperatures were shifted in the presence of Ni. These results indicate that the catalytic activity of MoS2/Ni materials may not only be influenced by chemical differences when Ni is added, but that different MoS2 structures could also impact catalytic properties.

In situ investigation of the evolution of layered chalcogenide catalysts during synthesis and processing

256th National Meeting (2018)

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