Size-Specific Infrared Spectroscopic Study of the Reactions between Water Molecules and Neutral Vanadium Dimer: Evidence for Water Splitting

Investigation of the reactions between water molecules and neutral metal clusters is important in water splitting but is very challenging due to the inherent difficulty of size selection. Here, we report a size-specific infrared-vacuum ultraviolet spectroscopic study on the reactions of water with neutral vanadium dimer. The V2O3H4 and V2O4H6 products were characterized to have unexpected V2(mu 2-OH)(mu 2-H)(11-OH)2 and V2(mu 2-OH)2(11-H)2(11- OH)2 structures, indicative of a water decomposition. A combination of theory and experiment reveals that the water splitting by V2 is both thermodynamically exothermic and kinetically facile in the gas phase. The present system serves as a model for clarifying the pivotal roles played by neutral metal clusters in water decomposition and also opens new avenues toward systematic understanding of water splitting by a large variety of single-cluster catalysts.