UV light activation of TiO2 for sensing formaldehyde
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作者:whhcrk
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发布时间: 2016-09-09
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Using a novel platform with the ability of high throughput resistance measurement (HT-RM), theresponses of UV light activated TiO2for formaldehyde sensing were studied. A way to let TiO2besensitive, recovering fast, and humidity less sensitive for formaldehyde sensing under UV light acti-vation by moderate temperature heating was proposed. The performance of TiO2for formaldehydesensing under different humidity was also presented. The results showed that, 60◦C was the optimumsensing temperature to show high gas responses and low humidity dependence of sensor resistance. Theconcentration–resistance calibration curves to formaldehyde was established at working temperatureof 60◦C. The concentration of formaldehyde could be detected under 0.1 ppm with the C–R calibrationcurves. 30 repeat measurements of 100 ppm formaldehyde measured under humidity of 18.24 mg/L atworking temperature of 60◦C showed stable responses. The results in this paper present a promisingway to use light activated TiO2 as a gas sensing material with high performances.
The structural stability of TiO2 thick films on Au and Pt electrodes was investigated under UV light activation for sensing formaldehyde in moisture circumstances. A chameleon phenomenon of TiO2 on the anode was found on the Au electrode samples, while no color changed on the Pt samples. The discolored (puce) TiO2 powders were characterized by X-ray photoelectron spectroscopy, where the generation of Ti3+ was verified. Different mechanisms that caused the disparities between the Au and Pt ones were discussed in detail. With the purpose of further evaluating the gas sensing performance stability, four test circles were performed. The Au electrode samples emerged an irreversible drift, while the Pt samples perfectly recovered to initial state undergoing a transitory 300 ◦C thermal cycle. The results in this paper show that Pt electrode is a suitable choice for TiO2 sensing formaldehyde in moisture circumstances.
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