Palladium Hydride as a Reference Electrode in Aprotic Solutions

Abstract

The results of a variety of electrochemical tests indicate palladium hydride (β-PdH) functions as a thermodynamic reference electrode in three aprotic solutions containing H2(g) and solvents of dichloromethane, dimethylsulfoxide, and acetonitrile. For enhanced electrical conductivity all solutions contained 0.2 M of an ionic liquid, 1-methyl-3-butyl imidazolium tetrafluoroborate. As is required of all thermodynamic reference electrodes (i) the potential of β-PdH was stable, (ii) its small amplitude anodic and cathodic polarization were reversible, and (iii) it exhibited Nernstian behavior assuming that the hydrogen cation activity is controlled by the concentration of adsorbed hydrogen, which is set by the partial pressure of H2(g).