Interface Dynamics in ZnO–Ga₂O₃/Nanocrystalline Diamond Heterostructures for Room-Temperature Hydrogen Sensing

Hydrogen sensors are critical for safety and efficiency in industrial and energy applications, particularly in the evolving hydrogen economy. Herein, we present a hydrogen sensor based on ZnO, Ga 2 O 3 (GaO), and nitrogen-doped ultrananocrystalline diamond ( N -UNCD), demonstrating superior sensing performance with minimal decay (<3.1%) after 30 days of operation. The ZnO–GaO/a-ND heterostructure exhibits a unique surface morphology, attributed to the incorporation of wide-bandgap Ga 2 O 3, which enhances electron mobility and improves charge transfer mechanisms. The sensor achieved a high response of 72.1% for 500 ppm of H 2 at room temperature, with excellent reproducibility over 15 on–off cycles and stable operation under varying conditions. The heterostructure also showed remarkable selectivity for H 2 over interfering gases, including NH 3, CO 2, and acetone, and retained stability under extended operation. This work will contribute to the literature, as no prior studies have explored the synergistic effects of ZnO, GaO, and N -UNCD for hydrogen sensing, establishing a strong platform for developing next-generation gas sensors with enhanced sensitivity, selectivity, and long-term stability.