Ultrasensitive room-temperature NO2 gas sensor based on graphene-modified Cu2O nanocomposites: A combined experimental and first-principles study

Nitrogen dioxide (NO 2 ) gas detection is crucial for environmental monitoring and pollution control. Here we report an ultrasensitive room-temperature NO 2 gas sensor based on graphene-modified Cu 2 O nanocomposite using a simple hydrothermal method. Gas sensing tests of the composites with different graphene contents reveal that those modified with 0.4 wt% graphene (0.4G-Cu 2 O) demonstrate the best performance, showing three times higher sensitivity than that of pure Cu 2 O. Additionally, 0.4G-Cu 2 O exhibits significantly reduced response and recovery times of 20 s and 65 s, respectively, which are notably shorter than those of many other sensing materials. These advantages were attributed to the unique nanostructure formed by graphene and Cu 2 O, where graphene enhanced the gas adsorption sites on the material surface and improved its conductivity. A combined experimental and first-principles study further elucidated the mechanisms behind the improved performance, highlighting the synergistic effects of graphene modification.