Hollow porous GaN nanofibers gas sensor for superior stability and sub-ppb-level NO2 gas detection

Accurate detection of NO2 gas with low concentration and high stability is of great significance to ecological protection and human health. In this work, hollow porous GaN nanofibers were fabricated by a low-cost solvothermal method and controlled nitridation process. Systematic characterizations results demonstrate large specific surface and abundant adsorpation sites of the GaN nanofibers. Excellent NO2 sensing performances were tested at 200 °C, including the high sensitivity of 22.9 (200 ppm), rapid response time within 11 s, high selectivity, and low detection limit (0.5 ppb). Furthermore, the anti-interference ability, cross-sensitivity characteristics, and long-term stability of the sensor in the actual working environment were also systematically investigated. The surface depletion layer model and the change of the potential barrier were used to explain the enhanced gas-sensing performance. The fabricated GaN sensor offered a promising candidate for real-time monitoring of sub-ppb-level NO2 gas in actual environments.