Iodine compounds speciation in HI-I2 aqueous solutions by Raman spectroscopy

► Iodine compound speciation in ternary mixtures HI-I2-H2O. ► Thermochemical sulphur-iodine cycle for hydrogen production. ► Raman spectroscopy investigations at varying I2:HI ratio. ► Polyiodines and polyiodides species have been evidenced only for I2:HI ratios higher than 1:1.