A novel hydrogen gas sensor based on hydrogen uranyl phosphate

The layered hydrate HUO₂PO₄·4H₂O is known to be a good selective proton conductor at room temperature. We have shown that the conductivity is dependent on the pressure of water vapour and good long term stability is obtained even at current densities as high as 5 mA/cm². The construction of porous composite electrodes of Pt and Pd is described and their use in hydrogen concentration cells is demonstrated. Furthermore, it is shown that these concentration cells give the correct voltage according to Nernst's law.