Building an appropriate active-site motif into a hydrogen-evolution catalyst with thiomolybdate [Mo3S13]2− clusters

Identifying and understanding the active sites responsible for reaction turnover is critical to developing improved catalysts. For the hydrogen-evolution reaction (HER), MoS2 has been identified as an active non-noble-metal-based catalyst. However, only edge sites turnover the reaction because the basal planes are catalytically inert. In an effort to develop a scalable HER catalyst with an increased number of active sites, herein we report a Mo–S catalyst (supported thiomolybdate [Mo3S13]2− nanoclusters) in which most sulfur atoms in the structure exhibit a structural motif similar to that observed at MoS2 edges. Supported sub-monolayers of [Mo3S13]2− nanoclusters exhibited excellent HER activity and stability in acid. Imaging at the atomic scale with scanning tunnelling microscopy allowed for direct characterization of these supported catalysts. The [Mo3S13]2− nanoclusters reported herein demonstrated excellent turnover frequencies, higher than those observed for other non-precious metal catalysts synthesized by a scalable route. Non-noble-metal-based MoS2 nanostructures are hydrogen evolution catalysts whose active sites are known to be located at the edges. Supported thiomolybdate [Mo3S13]2− nanoclusters have now been prepared that exhibit a structural motif similar to that of MoS2 edges. The nanoclusters, synthesized by a scalable route, demonstrate a high turnover frequency.