Flexible-Compatible ZnO/rGO Heterostructure Ammonia Sensors With Schottky Barrier Modulation and Neural Network Prediction

highly sensitive ammonia (NH3) gas sensor based on zinc oxide/reduced graphene oxide (ZnO/rGO) heterostructure thin film is presented, demonstrating enhanced interfacial charge transfer and improved sensing performance at room temperature. Microscopic and spectroscopic analysis confirm the coverage of rGO sheets over ZnO nanoparticles, increased defect density (ID/IG≈ 1.3), a 0.35 eV shift in Zn 2p binding energy, and approximately ∼72% enhancement in lattice oxygen contribution, indicating strong electronic coupling at the interface. Electrical characterization reveals an 18.4% reduction in Schottky barrier height and a 26.7% decrease in ideality factor, facilitating efficient carrier transport. The sensor operates over an NH3 concentration range of 0.5–50 ppm NH3 at room temperature, achieving a 75.02% response at 50 ppm (1.6× higher than that of ZnO). Fast response and recovery times of 18 s and 12 s, respectively, along with theoretical detection limit of 2.14 ppm, were achieved. The device exhibits good selectivity, repeatability, and stability with less thanR2) close to ≈ 0.99. The results demonstrate a combined heterostructure–engineering and data–driven strategy for advanced gas sensing applications.