Highly sensitive NO2 gas sensors based on heterostructured p-rGO/n-Ga2O3 nanorods

• Ga 2 O 3 nanorod sensing membranes were decorated by various rGO amounts. • Gas adsorption sites and oxygen vacancies increased with rGO decoration amounts. • Formation of p-n heterojunctions could improve response of NO 2 gas sensor. • rGO-decorated Ga 2 O 3 nanorod sensing membrane enhanced NO 2 gas sensor performance. • Shortened response and recovery times with increased rGO amounts. In this study, using a sensing membrane composed of p-type reduced graphene oxide (rGO)-decorated hydrothermally synthesized n-type gallium oxide (Ga 2 O 3 ) nanorods, nitrogen dioxide (NO 2 ) gas sensors were successfully fabricated. The characteristics of the rGO-decorated Ga 2 O 3 nanorods were analyzed by X-ray photoelectron spectroscopy (XPS). The experimental results indicated that the rGO decoration on the surface of the Ga 2 O 3 nanorods increased the amount of gas adsorption sites and oxygen vacancies, thereby enhancing electrical conductivity. Consequently, compared to NO 2 gas sensors utilizing only Ga 2 O 3 nanorods, the NO 2 gas sensors using rGO-decorated Ga 2 O 3 nanorod sensing membrane exhibited lower resistance, reduced activation energy, and higher response. Optimal response, reaching 51.14, was achieved by decorating with 15 mg of rGO. Additionally, the response and recovery times of the NO 2 gas sensors were shortened with an increase in the amount of rGO decoration on the Ga 2 O 3 nanorods. This improvement could be attributed to the trend of lower activation energy associated with an increased amount of rGO decoration. This study demonstrates the efficacy of rGO decoration in improving the performance of Ga 2 O 3 nanorod-based NO 2 gas sensors.