以濺鍍法製備Ag/Nafion電極感測硫化氫之研究

• Main Author: 蒲志淳
• Other Authors: M. C. Yang
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/01775329298102456685

碩士 === 國立成功大學 === 化學工程學系 === 87 === Hydrogen sulfide is a kind of pollutant from petroleum gas, waste water and waste gas in factories. It threatens to human health and plant safety. When the government, the industries, and the society pay more attentions on environ-mental protection and plant safety, the concerning to hydrogen sulfide will be intensified. In this search, Nafion 417 was used as a solid polymer electrolyte due to its superiorly mechanical properties, and silver was used as the sensing material due to its chemical activity. Ag was prepared on NafionR with DC sputtering system. The characteristics and reaction behaviors of Ag/Nafion were investigated. For preparing Ag/Nafion electrodes, the sputter power were 0.04, 0.09 and 0.15 KW; the chamber pressure were 0.0055, 0.011, 0.023, 0.033 and 0.046 torr; the sputtering time were 10, 15, 20, 25 and 30 min; and the substrate bias were 75, 125 and 150 V. According to XRD analysis, the prepared Ag/Nafion electrodes showed various ratios of (111), (220), and (200) phase. The potential range for limiting current is -0.25∼-0.1 V ( vs. Hg/Hg2SO4) with response time of about 100 sec. The sensing currents of hydrogen sulfide with Ag/Nafion were linear to H2S concentration. The sensitivity, calculated from the slope, was affected by sputter power, chamber pressure, sputter time, substrate bias voltage and gas humidity. When the chamber pressure was 0.011 torr without substrate bias voltage, the sensitivity were affected by sputter power and sputtering time. With the power of 0.04, 0.09 and 0.15 KW, the electrodes having the highest sensitivity were obtained with sputtering time of 20, 25 and 10 min, respectively. The corresponding sensitivity were 1.389, 1.64 and 1.579μA/ppm. When the sputtering time was 20 min without substrate bias voltage, the sensitivity were affected by sputter power and chamber pressure. With the powers are of 0.04, 0.09 and 0.15 KW, the electrodes having the highest sensitivity were obtained with chamber pressures of 0.023, 0.033 and 0.033 torr, respectively. The corresponding sensitivities were 1.906, 1.93 and 4.624μA/ppm, and the detection limits were 10, 10 and 60 ppm, respectively. When the chamber pressure and sputter time were 0.011 torr and 20 min, the electrodes having the highest sensitivity were obtained with applied bias voltage 75 V. The corre-sponding sensitivity were 3.605μA/ppm. The potential range for limiting current was -0.15∼-0.1 V (vs. Hg/Hg2SO4) in nitrogen with relative humidity 55 % and 100 ppm hydrogen sulfide. The response time was within 50 sec which was shorter than that in dry nitrogen. When the chamber pressure, sputtering time and sputter power was 1.1×10-2torr, 20 min, and 0.09 KW, respectively, the sensing currents were linear to the concentration of the hydrogen sulfide with detection limit of 50 ppm for electrodes prepared with bias voltage both 0 and 125 V. The corre-sponding sensitivity were 5.204 and 5.579 μA/ppm which were higher then that without humidity. Hydrogen sulfide is a kind of pollutant from petroleum gas, waste water and waste gas in factories. It threatens to human health and plant safety. When the government, the industries, and the society pay more attentions on environ-mental protection and plant safety, the concerning to hydrogen sulfide will be intensified. In this search, Nafion 417 was used as a solid polymer electrolyte due to its superiorly mechanical properties, and silver was used as the sensing material due to its chemical activity. Ag was prepared on NafionR with DC sputtering system. The characteristics and reaction behaviors of Ag/Nafion were investigated. For preparing Ag/Nafion electrodes, the sputter power were 0.04, 0.09 and 0.15 KW; the chamber pressure were 0.0055, 0.011, 0.023, 0.033 and 0.046 torr; the sputtering time were 10, 15, 20, 25 and 30 min; and the substrate bias were 75, 125 and 150 V. According to XRD analysis, the prepared Ag/Nafion electrodes showed various ratios of (111), (220), and (200) phase. The potential range for limiting current is -0.25∼-0.1 V ( vs. Hg/Hg2SO4) with response time of about 100 sec. The sensing currents of hydrogen sulfide with Ag/Nafion were linear to H2S concentration. The sensitivity, calculated from the slope, was affected by sputter power, chamber pressure, sputter time, substrate bias voltage and gas humidity. When the chamber pressure was 0.011 torr without substrate bias voltage, the sensitivity were affected by sputter power and sputtering time. With the power of 0.04, 0.09 and 0.15 KW, the electrodes having the highest sensitivity were obtained with sputtering time of 20, 25 and 10 min, respectively. The corresponding sensitivity were 1.389, 1.64 and 1.579μA/ppm. When the sputtering time was 20 min without substrate bias voltage, the sensitivity were affected by sputter power and chamber pressure. With the powers are of 0.04, 0.09 and 0.15 KW, the electrodes having the highest sensitivity were obtained with chamber pressures of 0.023, 0.033 and 0.033 torr, respectively. The corresponding sensitivities were 1.906, 1.93 and 4.624μA/ppm, and the detection limits were 10, 10 and 60 ppm, respectively. When the chamber pressure and sputter time were 0.011 torr and 20 min, the electrodes having the highest sensitivity were obtained with applied bias voltage 75 V. The corre-sponding sensitivity were 3.605μA/ppm. The potential range for limiting current was -0.15∼-0.1 V (vs. Hg/Hg2SO4) in nitrogen with relative humidity 55 % and 100 ppm hydrogen sulfide. The response time was within 50 sec which was shorter than that in dry nitrogen. When the chamber pressure, sputtering time and sputter power was 1.1×10-2torr, 20 min, and 0.09 KW, respectively, the sensing currents were linear to the concentration of the hydrogen sulfide with detection limit of 50 ppm for electrodes prepared with bias voltage both 0 and 125 V. The corre-sponding sensitivity were 5.204 and 5.579 μA/ppm which were higher then that without humidity.