Fumed SiO2-H2SO4-PVA Gel Electrolyte CO Electrochemical Gas Sensor

The conventional CO electrochemical gas sensor uses aqueous H2SO4 solution as electrolyte, with inevitable problems, such as the drying and leakage of electrolyte. Thus, research on new alternative electrolytes is an attractive field in electrochemical gas sensors. In this paper, the application of a new fumed SiO2 gel electrolyte was studied in electrochemical gas sensors. The effects of fumed SiO2 and H2SO4 contents on the performance of the CO gas sensor were investigated. The results showed that the optimized composition of the SiO2 gel electrolyte was 4.8% SiO2, 38% H2SO4, and 0.005% polyvinyl alcohol (PVA). Compared with aqueous H2SO4, the gel electrolyte had better water retention ability. The signal current of the sensor was proportional to the CO concentration. The sensitivity to CO was 78.6 nA/ppm, and the response and recovery times were 31 and 38 s, respectively. The detection limit was 2 ppm. The linear range was from 2 to 500 ppm. The gel electrolyte CO sensor possesses equivalent performance to that with aqueous electrolyte.