Carbon monoxide (CO) is a colorless, odorless, and toxic gas that is harmful to humans. CO binds to hemoglobin in the blood, which in turn causes symptoms of oxygen deprivation in human tissues. The main source of CO is the incomplete combustion of carbonaceous fuels. In addition to natural phenomena such as forest fires and volcanic eruptions, a large amount of CO is also generated by industrial processes and motor vehicle exhaust in urban areas. In recent years, the use of fossil fuels has gradually increased, making the CO pollution to atmosphere serious[2,3]. In addition, the detection of CO concentration exhaled from the human body can be used for clinical diagnosis[4,5]. Therefore, it is necessary to develop CO sensors with high sensitivity and real-time monitoring characteristics.