Reversible Hydrogen and Pd Hydride Reference Electrodes with Electrochemically Supplied H₂ for High Temperature and Pressure Electrochemistry

A reversible hydrogen electrode (RHE) and a Palladium hydride (PdH) reference are proposed with convenient design for use at high temperatures pressures (HTP). constant electrochemically driven supply of H 2 on the RHE or PdH surface ensures preservation equilibrium potential mixed ( α + β )-phase in layer, respectively, thereby ensuring stable potentials HTP conditions prolonged periods time. Furthermore, is calibrated as function temperature pressure respect to RHE. In contrast earlier calibration attempts, we find that independent pressure, value ∼55 mV vs 25 °C, 1 bar, 45 wt% KOH. When charged enough assume H-rich -phase only, its follows RHE, but shows sluggish equilibration upon changing temperature, due slow diffusion -PdH.