Proton NMR studies on concentrated aqueous sulfuric acid solutions and Nafion-H

Sulfuric acid containing limited amounts of water, H2SO4.nH2O with 0.23≤n≤4, has been studied by 1H broad-line NMR at 4 K and MAS NMR at room temperature. The broad-line NMR spectra indicate the formation of H3O+ and HSO4 - ions. H2SO4.2H2O is correctly written as H3O+HSO4 -.H2O. The results are compared with the Nafion- H/water system.