Fabrication of Carbon Quantum Dots/Alq3 Layer for NO2 Gas Sensor

The gas sensors were prepared using carbon quantum dots (CQDs) using an electrochemical method after mixing the CQDs with Tris (8-hydroxyquinoline) aluminum (III) (Alq3) polymer. A spin coating technique was used to deposit CQDs/Alq3 composite film on glass substrates with a ratio of 1:1. The CQDs/Alq3 gas sensor showed a sensitivity of about 24٪ at a temperature of 300 ℃, and this was calculated after measuring the change in the resistance of the samples with a response time of 2 and 8sec recovery time. The sensor showed a good response for nitrogen dioxide (NO2) gas. However, the sensitivity, response time, and recovery time for the CQDs gas sensor when exposed to NO2 gas at 300 °C were 78%, 4s, and 129s, respectively. The results showed that the best sensor CQDs/Alq3 led to a reduction in the recovery time, which shows the importance of the Alq3 polymer in improving the properties of the gas sensor.