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Temperature dependence and degradation of gasochromic response behavior in hydrogen sensing with Pt/WO3 thin film

2014; Elsevier BV; Volume: 558; Linguagem: Inglês

10.1016/j.tsf.2014.02.080

1879-2731

Shinji Okazaki, S. Johjima,

Analytical Chemistry and Sensors

The gasochromic characteristics of a sol–gel derived Pt/WO3 film as a hydrogen sensitive material were evaluated at various temperatures using optical transmittance measurements in the near-infrared region. The sensitivity of the film was high and a change of more than 60% in transmittance was observed at room temperature and higher with exposure to a mixture of 4 vol% H2 and N2 balance. The response rate was fast and the 90% response time was ca. 10 s at 25 °C. However, the recovery rate was slower than that of the response, which suggests that the recovery process may not be a reverse reaction of the response mechanism. As the temperature was lowered, the response became slower and weaker, although a reasonable response was still observed at − 40 °C. However, a deterioration of response behavior at − 40 °C appeared after the repeated exposure to temperature cycles from − 40 to 100 °C. Although the sensitivity and response rate became considerably worse after this exposure, the sensing performance was completely restored by heat treatment at 500 °C for 1 h.