A high selectivity and low detection limit carbon monoxide sensor based on Au-GO/Co-ZnO composite material.

Metal oxide semiconductor gas sensors offer high sensitivity and low-cost gas detection. However, low selectivity and poor stability are significant challenges associated with these sensors. In this study, we designed a sheet-like stacked zinc oxide (ZnO) nanomaterial using ZIF-67 and prepared the nanomaterial AGCZ-2 by doping with gold-modified graphene oxide (GO). This material demonstrates rapid and sensitive detection of low concentrations of carbon monoxide (CO) gas and exhibits excellent selectivity towards CO. The crystal structure, microstructure, elemental composition, and pore size of the material were characterized and analyzed using XRD, FESEM, EDS elemental analysis, TEM, and N₂ adsorption-desorption techniques. The CO gas sensing performance of the sensor prepared in this study was tested, and the results showed that the AGCZ-2 sensor, operating at an optimal temperature of 260 °C, had a response value of 5.84 for 50 ppm CO, with response and recovery times of 103 s and 84 s, respectively. In terms of selectivity, the response of the AGCZ-2 sensor to CO was 3.84 times that of the second most sensitive gas (hydrogen), indicating excellent selectivity towards CO over hydrogen. Additionally, the sensor exhibited good stability and repeatability, with a relative standard deviation of 2.27% for the response values to 5 ppm CO gas over five consecutive tests. Over a 28-day testing period, the sensor's response to 5 ppm CO exhibited a decay rate of 5.22%, with a relative standard deviation of 2.41.