Water‐Splitting “Without Water”: Splitting of the Crystallised Water of Hydrated Salts

In contrast to the liquid phase of water, the structural molecular realities of H₂O molecules embedded in crystallised salts vary little and can be precisely determined. However, this water, which is neither in the liquid nor in the gas phase, has not yet been used in water electrolysis. Here, we demonstrate that water electrolysis can be achieved without the addition of (liquid) water through experiments with a wide range of hydrated salts and organic solvent suspensions. We obtain an excellent correlation between the position of the FTIR O─H stretch vibration of the hydrated salts and the onset of the OER potential from CV measurements. Together with first-principles density functional theory calculations, we demonstrate that intramolecular bonds in crystallised water can be effectively controlled through choice of the inorganic salt. Targeted manipulation of the bonds in the H₂O molecule is a promising new approach to more efficient hydrogen production.