Investigation of gas-sensitivity of sensor structures to hydrogen in a wide range of temperature, concentration and humidity of gas medium

Abstract

Investigation of gas-sensitivity of sensor structures to hydrogen in a wide range of temperature, concentration and humidity of gas medium a b s t r a c t Response to H 2 of seven sensor structures of SnO 2 with various catalytic additives, made by thick-film technology, was investigated in a dry gas medium at a concentration of 200 ppm H 2 in a temperature range of 100-600 • C. Concentration dependence of six sensors (pure SnO 2 and doped with five catalytic additives: 3% Pd, 3% La 2 O 3 , 1% Pt + 3% Pd, 1% Sb 2 O 5 + 3% La 2 O 3 and 3% Pd with a support layer from Al 2 O 3 ) was investigated in a range of 1-19,700 ppm H 2 of different relative humidity (RH) in a range of 0-100% RH at two operating temperatures. The resistance and response of the sensors weakly depended on the humidity of the gas medium at RH ≥ 0 or 10%. Arithmetic mean values of response and resistance in the range of 0 (10)-100% RH were approximated by linear functions of log(S ma − 1) = B + n log C and log R ma = A + k log C, respectively.Based on the comparative analysis of experimental data (response to H 2 , reproducibility of indications, influence of humidity on the resistance and response, response threshold and a resistance drift in pure air), the best for H 2 detection were the two sensor structures of pure SnO 2 and SnO 2 + 3% La 2 O 3 , working at temperatures 500 • C and 450 • C, respectively. Formulas for resistance and response of these sensors were presented, which allowed estimation of H 2 concentration in air based on the measured parameters. Reproducibility of indications in the range of 1-19,700 ppm H 2 was within 4-10%. The response threshold was 0.08 ± 0.006 ppm H 2 in the mentioned range of humidity at the response equal to 1.1.The interpretation was given for the mechanism of interaction of H 2 with the catalytic surface of semiconductive sensors. The present sensors can be recommended as the primary transducer of H 2 concentration in air for the gas control devices.

Nanocrystalline SnO2 film prepared by the aqueous sol–gel method and its application as sensing films of the resistance and SAW H2S sensor

“…In the practical application, the influence of relative humidity can be eliminated by using the dual delay line structure and differential output. Furthermore, the influence on the sensor performance induced by the change of relative humidity can be reduced by doping some noble metals [27,28]. Fig.…”

Fabrication of Pd Doped WO3 Nanofiber as Hydrogen Sensor

“…Also, this increases the response and selectivity as well as decreasing the maximum working temperature of the sensors. For hydrogen sensors, modification of metal oxides, especially WO 3 , by metal additives such as Pt, Pd, or Au, using different techniques is under intensive investigation [24][25][26][27][28][29][30][31].…”

Reducing Humidity Response of Gas Sensors for Medical Applications: Use of Spark Discharge Synthesis of Metal Oxide Nanoparticles

“…The sensor responses to different concentrations of hydrogen in the range from 100 to 500 ppm are given in Figure 9 . The corresponding plot showing sensor response as a function of hydrogen concentration demonstrates the usual power law ( Figure 10 ), which is typical of such sensors [ 28 ].…”