A chemiresistive ppt level NO2 gas sensor based on CeO2 nanoparticles modified CuO nanosheets operated at 100 °C

Inducing chemisorbed oxygen and constructing heterostructures are important strategies for improving sensors performance. Therefore, we prepared cupric oxide (CuO) composite modified by cerium dioxide (CeO2) via a low-cost hydrothermal method and calcination technology. The material was analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray powder diffraction (XRD) techniques, confirming the composition of the sensing material and analyzing the morphology. Afterward, different morphology-sensing materials are characterized using Brunauer‐Emmett‐Teller (BET), and the influence of the specific surface area of different morphologies of the sensing material on the sensing characteristics was explored. During gas sensing tests, the response of the optimal sample to 50 parts per million (ppm) nitrogen dioxide (NO2) gas is 9.59. Meanwhile, the detection limit is 600 parts per trillion (ppt), and the response and recovery times are 15 s and 110 s, respectively. Additionally, we test the selectivity, responses under different relative humidity levels, and long-term stability (30 days) of the optimal sample. Therefore, the sensor has great prospects in applications such as real-time detection and trace monitoring. Eventually, according to the structure, composition, and morphology of the material, we proposed a sensing mechanism for enhancing the sensing characteristics of NO2 gas sensor.