Hydrogen Sensor Based on Au and YSZ/HgO/Hg Electrode for in Situ Measurement of Dissolved H_(2) in High-Temperature and -Pressure Fluids

摘要

Gold as a hydrogen-sensing electrode for in situ measurement of dissolved H_(2) in aqueous solutions under extreme conditions is reported. The dissolved H_(2) sensor, constructed with a Au-based sensing element and coupled with a YSZ/HgO/Hg electrode, is well suited for determining dissolved H_(2) concentrations of aqueous fluids at elevated temperatures and pressures. The Au electrode is made of Au wire mounted in a quartz bar, which can be pressurized and heated in the high-pressure and -temperature conditions. The Au-YSZ sensor has been tested for its potential response to the concentrations of dissolved H_(2) in fluids by using a flow-through reactor at high temperatures up to 400 deg C and pressures to 38 MPa. Good sensitivity and linear response between the hydrogen concentrations in the fluids and the H_(2) sensor potentials are reported for hydrogen gas in the concentration range of 0.1-0.001 M H_(2) in aqueous fluids at temperatures up to 340 deg C and 30 MPa. Nernstian response of the cell potential to dissolved H_(2) in fluids was determined at 340 deg C and 30 MPa, described as follows: (DELTA)E velence 0.9444 + 0. 0603 log m_(H2) The experimental results indicate that the Au-YSZ/HgO/Hg cell can be used to measure the solubility of H_(2) in aqueous fluid at temperatures and pressures near to the critical state of water. Thus, this type of Au hydrogen sensor could be easily used for in situ measurement of H_(2) in hydrothermal fluids in a high-pressure vessel, or at midocean ridge, due to its structure of compression resistance.