Study On Limiting-current-type Hydrogen Sensors With Dense Diffusion Layer Based On Mixed Conductor

Hydrogen is an important industrial raw material. The industrial importance and operational safety of hydrogen demand reliable hydrogen sensor to ensure the effectiveness of the process and hazards control systems. The new dual-phase proton-electron mixed conductors of SrZr0.95Y0.05O3-δ(SZY)/Sr0.88Y0.08TiO3(SYT)、Sr(CeZr)0.90Y0.10O3-δ( SCZY ) /Sr0.88Y0.08TiO3 ( SYT ) and BaCe0.8Gd0.2O3-δ( BCG ) /Ce0.8Gd0.2O2(CGO) were investigated, and limiting-current-type sensors using proton conductor as an electrolyte and mixed proton-electron conductor as dense diffusion barrier is constructed. The crystalline phase and electrical conductivity of mixed conductors are investigated by XRD and EIS, respectively. In addition, hydrogen sensing properties of the sensor are measured.The hydrogen sensor which SZY/SYT、SCZY/SYT=9/1、SCZY/SYT=5/5 are used as dense diffusion appear limiting current. The sensitivity of these sensors have good sensitivity. The sensitivity of these sensors are 0.0705μA·ppm-1、0.0045μA·ppm-1、2.2511×10-2μA·ppm at 800℃, respectively. The results indicate that hydrogen sensing of the sensors can be improved by changing the proportion of BCG/CGO. While the proportion of BCG/CGO is 4:6 to 7:3, the hydrogen sensors have wide limiting current, and as we expected, the limiting current increased almost linearly with increased hydrogen concentration. The cross-section of the limiting-current hydrogen sensors are analysed by SEM, the interface between mixed conductor and electrolyte was clear. It is illuminated that these have good compatibility. The limiting current reach maximum whlie the proportion of BCG/CGO is 4:6; the hydrogen sensor with it as dense diffusion barrier has good linear relation under the hydrogen concentration of 300ppm~17700ppm at 650℃~800℃. The sensitivity of this sensor can achieve microampere, and it is 2.3700μA·ppm-1 at 800℃.