A reference electrode for use in supercritical difluoromethane

We describe the assembly and characterisation of a reference electrode for use in supercritical difluoromethane (R32). The reference electrode is constructed from a europium doped lanthanum fluoride crystal contacted by silver loaded epoxy and encased in a silicate epoxy. The reference electrode can withstand pressures and temperatures up to at least 20 MPa and 360 K, typical operating condition for electrochemistry in supercritical difluoromethane (scR32). The performance of the new reference electrode is compared to that of a platinum pseudo reference electrode in scR32. The redox potential of the decamethylferrocene couple in scR32 containing 20 mM [NBun4][BF4] at ∼17.6 MPa and 359 K was 0.088 ± 0.015 V against the new silver contacted lanthanum fluoride crystal based reference electrode.