Abstract:

In order to monitor the CO gas in the environment effectively, a new CO sensor which could work at room temperature was designed and fabricated. The sensor is composed of active carbon filtrated cap, Pt sensing electrode, Nafion membrane, counter electrode, the isolation and reservoir. The design of the reservoir provides the humidity environment that Nafion membrane needed for the normal work. The sensing properties of the sensor are mainly determined by the Pt sensing electrode. The preparing conditions of chemical deposition were mainly investigated. When the concentration of H2PtCl6 and NaBH4 are 5 mmol/L and 30 mmol/L, respectively, and the pH value of NaBH4 solution is 13, the sensor gave the best sensing performance. The response current is 107 nA, and the response and recovery time are 40 s and 50 s, respectively, when the concentration of CO is 400×10^-6. When the CO volume fraction ranges from 50～400×10^-6, the response current value of the sensor has a good linear relationship with the concentration of CO gas.

Key words: gas sensor, sensitive electrode, CO, Nafion membrane