Detection Mechanism of Amperometric Sensor Based on pH-Dependent Electrode Reactions of Metal Oxide for Acidic and Basic Gases Sensing

抄録

An amperometric sensor based on pH-dependent electrode reaction of RuO₂ electrode for the detection of acidic and basic gases has been developed. The sensor shows good characteristics of the response and stability for the sensing of CO₂ and NH₃. The detection mechanisms of the sensing reactions were studied by using different pH buffer solutions and X-ray photoelectron spectrometry (XPS). The response currents were hardly observed for acidic and basic gases, such as CO₂ and NH₃, respectively, by using the sensor containing a pH buffer solution. The steady current is concerned with variation of pH of buffer electrolyte. By measuring the XPS spectrum of RuO₂ electrode surface after acidic or basic gas flowing, the changes of the oxidation states of RuO₂ was observed. The results proved that the detection mechanism of the sensor is based on the pH dependent electrode reaction of RuO₂ which response current is determined by the concentration of hydrogen ion or hydroxide ion induced by acidic and basic gases.