The Ouzo effect to selectively assemble molybdenum clusters into nanomarbles or nanocapsules with increased HER activityElectronic supplementary information (ESI) available. See DOI: 10.1039/c8cc07402j

Metal cluster nanoparticles are obtained by simple solvent shifting called the Ouzo effect. Remarkably, the assembly of [{Mo 6 Br 8 }L 6 ] 2− (L = Br − or NCS − ) cluster units can be directed into nanomarbles or nanocapsules depending on the cluster chemistry. When deposited on electrodes, these nanoparticles show good activities in electrochemical water splitting under mild conditions. Molybdenum clusters assemble spontaneously into nanocapsules or nanomarbles depending on their solubility in a water/THF mixture.